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GIFT OF
A consideration of various factors affecting
the net duty of irrigation water
Philip Rowland Roosegaarde Bisschop
B . S . ( Uni v ersity of South' , jAtfr'i c a,) 9 18
In *e*da^ *l^^:v^^
THESIS
Submitted in partial satisfaction of the requirements for the
degree of
MASTER OP SCIENCE
in
Civil Engineering
in the
GRADUATE DIVISION
of the
UNIVERSITY OP CALIFORNIA
Approved _ . ______
^/Tinstructor in Charge
Deposited in the University Library
Librarian
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Letter of Transmittal
Prof. Charles Derleth, Jr.,
Dean of the College of Civil Engineering,
University of California.
Dear Sir:
In accordance with the regulations
of the College of Civil Engineering, I herewith
beg to submit to you for your approval my Thesis
for the degree of Master of Science.
I remain, Sir,
Yours faithfully,
Berkeley,
April 30th, 1921.
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TABLE OP CONTENTS p
Letter of Transmittal.
Chapter I
Introduction
Definition of net duty and max-
imum economical duty
Chapter II
The Texture and Structure of the Soil . ,
Grades of soil
Structure of the soil
The moisture contained in the soil
Chapter III 28
The Climate ......... .........................
The annual precipitation and its
distribution ........ . .................
The start of the Irrigation System .......
Chapter IV 34
Moisture Distribution in the Soil ............
Downward, upward and lateral
movement of soil moisture ............
The extent of distribution ...............
Results of field experiments .............
Conclusions reached ......................
Chapter V 5^
Character of Soil and Subsoil ................
Hardpans .................................
Gravel and sandy subsoils ................
Chapter VI 67
Ejrapj)ration, Percolation and Surf ace. J/asJbe
Losses ......................................
The process of evaporation ...............
Cultivated and uncultivated soils .....
Mulching ..............................
Furrow irrigation .....................
The effect of the type of soil on per-
colation losses .........................
Size of irrigation head ..................
Frequency of application ..............
Length of run .........................
Lateral percolation in furrows ........
Surface waste .....
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Chapter VII 93
The Fertility of the Soil
Need of fertilizers
The function of organic matter in
the soil
Cover crops
Chapter VIII 99
The Crops
Plant growth
The effect of irrigation at different
periods of plant growth
American irrigation practice on dif-
ferent crops
Diversification of crops
Chapter IX ]_ 9
Yields of Various Crops under :...VaryJLn
Amounts of Irrigation Applications
Results of experiments on
( 1 ) Alfalfa
(2) Potatoes
(5) Cereals
(4 ) Citrus fruits
(5) Deciduous fruits
Chapter X
Tabled"
(1) The net and gross duty of various
irrigation projects for the year
1917
(2) Distribution of irrigation water for
net duty on various projects for
the years 1912-1919
(3) Average seasonal duty of water on
various Irrigation Projects for
the years 1912-1917....
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BIBLIOGRAPHY
(References are indicated by number.)
1. Soils Lyon, Pippin and Bucionan.
2. Principles of Irrigation PracticeWidtsoe.
3. Irrigation and Drainage- -King .
4. Irrigation Management- -Newell.
5. Irrigation in the United States--Teele.
6. Irrigation Practice and Engineering, Vol.I?-Etchevery.
7. Soils--Hilgard.
8. Physics of Agriculture --King.
9. Evaporation from Irrigated Soils--Portier and Beckett
--United States Department of Agriculture ,, Bulletin 248.
10. Distribution of water in the soil in Furrow Irrigation
--Loughridge and Portier, United States Department
of Agriculture, Bulletin 203.
11. Irrigation and Soil Moisture Investigations in
Western Oregon--W. L. Powers, Oregon Agricultural
Experiment Station, Bulletin 122.
12. Duty of Water investigationsDon H. Bark, Ninth Bi-
ennial Report of the State Engineer of Idaho.
13. The Duty of Water in Cache Valley, UtahHarris, Utah
Agricultural College and Experiment Station,
Bulletin 173.
14. The Movement of Water in Irrigated Soils Widtsoe and
McLaughlin. Utah Agricultural College, Experiment
Station, Bulletin 115.
15. Yields of Crops with Different Quantities of Irriga-
tion Water--Widtsoe and Kerrill, Utah Agricultural
College Experiment ^tateion, Bulletin 117.
Em- nlqq Jt'3. , no -&I - -a I ioS I
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ifiB no i 4s si- IT: I -S
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axe I loci bne 30 1:
.321
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'</*'? 4 o + '* "^^fc^'^"
16. Methods for Increasing the Crop Producing
Power of Irrigation Water--Widtsoe and Merrill.
Utah Agricultural College, Experiment Station,
Bulletin 118.
17. Studies on Capacities of Soils for Irrigation
Water--0. W. Israelsen--Journal of Agricultural
Research, Vol. XIII, No. 1.
18. Investigations of the Economical Duty of Water
for Alfalfa in the Sacramento Valley- -E. R. Adams.
19. Report on Irrigation Investigations nn the North
Side Minnidoka Project. Harding.
20. Water Requirements of Soils in the Sunnyside Valley
Irrigation DistrictHarding.
21 Report on Irrigation Investigations at Billings,
Montana- -Harding .
22. Flow of Irrigation Water over Soils in Different
Methods of Application- -Harding.
25. The Use of Water from the Tuolumne by the Modesto
and Turlock Irrigation Districts Etcheverry and
Means .
24. Depths to which different Soils may be wetted by
Irrigation Water 0. W. Isrelsen.
25. The_ Capillary Movement of Soil Moisture--W. W.
McLaughlin, United States Department of Agriculture,
Bulletin 855.
26. Annual Reports of the Reclamation Service, 1912--1919.
27. Experiments of the Economical Use of Irrigation Water
in IdahoDon H. Bark, United States Department of
Agriculture, Bulletin 539.
28. Soil Moisture Studies Under IrrigationHarris and
Bracken- -Utah Agricultural College Experiment Sta-
tion, Bulletin 159.
39. Irrigation Projects Data E. A. Moritz, Vol. 9, No.
11, Reclamation Record.
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21 1
CHAPTER I
INTRODUCTION
It is well recognized that, regardless of the
crop irrigated, a proper knowledge of the duty of water is
essential to both the Farmer and the Engineer. Such, es-
pecially, is the case in newly developing irrigated and ir-
rigable districts. With the growth and development of the
irrigated sections the question of advantageously and eco-
nomically using the limited amount of irrigation water is
becoming more and more apparent. As the irrigable lands
become more settled, more frequently is it asked just how
much water is necessary to produce a good crop, and under
what conditions of irrigation can the largest returns per
acre foot of water as well as pe r acre be expected.
In South Africa especially, in its present period
of development, is it essential that more definite informa-
tion on which to base an answer to these questions, be ob-
tained. It is a matter of extreme regret that up to the
present no experiments, to determine the water Duty of our
South African crops under the many varying climatic condi-
tions, have as yet been undertaken.
It is essential to the farmer and irrigator to
lo asslbifl^sT . -tar-d- fossirsfooe-i llsw al tfl
ai locfsvir Ic "^cfx/b ec'-t to Qgbei^cni. i^qc--iq s ^fcsct-s^liii qoio
-39 ,fiow2 ,i3srii,iiii aiict bi:& r f9rri r iB'>j. srl xl^ocf od 1
-ii brtB bsctjagiiTii gciqolsvab ^Xwsrt nl 0aeo axid 1 ai
sxi* lo
-oos bitfj Yia^cQ^fid-nsvbs lo rcoictaaup srl^ enoJWaes JJ
ai -iod;.8w ncl.jB3ii r ii lo cj-m/ofon bs^lmll srW gniaw ^
a>nx?I aldB^iiiJ: s/'uf sA . ctaeiaqqa SIOJB bne eiorvi
tebror .bxiB ',qo r io Loorv^ aouboiq o.t Y~ ssa 3osn ai
ioc sni.^31 d 693^^1 siicf HBO nolJs^iiil lo anold'ibfioo-
.bsdoec^xa sJ S-TOB -i sq as Xiew SB IS^BW lo c^ool 9105
be it d-rfeaoiq a-j i n^.r^-L 210 ^^ BoxilA ii^efi nl
-aitnolnx scf inilsb s-xont d-Brf* Icid-nsass tfi ai tdroiuqclovab lo
-do 3o r , aaolj39JJp seerld- o^ iswsns HB as ,-ioldvr no rscid-
sx^ o-j qu Jsxid- ;t9 r i33'! o^sictxe .lo f i: rj si tfl ..bsrxiBJ
tcro. lo '^jyG loijew srf^ snim- ' xs on Jaag-
-tbnoo pid-Birrilo ^nlvr 1 ^^ &&& ^ -' I3 naoiilA xiv
baa - OB 30 ax
have this information that he may make the arrangement
for an adequate water supply, that he may avoid injury
of his soil through the application of too much water,
and that he may adjust to his land the amount available
to him, so as to obtain the largest possible returns per
acre foot of water applied. Further, he should have an
of
under standing /the underground movement of the water after
its application, that he may be sure, on the one hand,
that excessive losses are not occurring through deep per-
colation, and, on the other hand, that the irrigation wa-
ter is penetrating into the soil sufficiently deep to give
proper nourishment to the feeding roots of his crop.
It is essential to the Engineer to have such in-
formation at his disposal in order that he may determine
how large a canal to build to supply a definite area, or,
having determined the quantity of water available and the
cost of bringing it to the tract to be irrigated, he could
not decide upon the practicability of his scheme because
of his inability to determine how large an area the water
supply is able to serve.
The Engineer, too, should have an accurate know-
ledge of the factors that influence the amount of water
d7i9i::9 gneiss erid Q'Aan *Bm eii tfsitt nold'amio'irii aldd"
biovfi -sjjsm 9rf tferfd 1 . ijlqqtfe letfaw stffiifpsbjs IIB tol
jsw rloxiTH ood' lo nc/.o3CJcIqqs grid 1 jigxroidd' lioa sir! io
aidi^aoq cJ-sssiBi axfcf rriacfcfo oct as oa ,miii
rus svsrl blucila a;i (-is-dchritfi .bsllaqs r fs.tw Io oool
lo
ij lo in9:,.avo;ri bajjO'i^-iaL.'.;. 9 ^ .'.";:. .:J'L ; 3 '':
xl ario s;y no ,31; /a -3d %&& && ^Bitcf , noli JB oil qqs aJi
o'ir'j yiliij/ooo ooc sis asaacl eviaaco.'.o l-aifcf
-aw ncid-a^iiil o^d" j/saj ,>isri laxid-o arid- nc -bas -a
vig ocf qsoa ^XofiDioillua Ixos end 1 o^ii gxiio^'icJ-onsq si
.qo r io a In io aci-co'i gnibosl sricj 1 o^ drxamfiaiixfor: r ioqoiq
rcl :, ; ojya avjezl od" issrii^n^-sii'd- od l^l^neeas si ctl
n gxi $s:L - r iobio ni laaoqaib aiif ;ts noictfir.^ol
.B3 r xs sciini'lab a ^Xqqire od" bii0d od" iBnflo B 93'i.el won'
>HB 9lcfGllj8v 'isd-sw I'o Tj^l^nBjjp &d$ bsnliTrssd-ab aniVBri
9. r [ .bod-js -.t'l-rl 9cJ od". d'oaid' sild 1 od* ctl ':icf lo d-soo
%
9axjBostf sKtsifoa aiii lo Y*-^--^ 30 ^^ 03 '^? d ^ noqjj sbioab ^ort
isdsw eti* asTB ne 9316! wod = '..ia'ani aid lo
- . t Ids ai T iq
worpi ad'B'-iDOOB HB o . . , ' ._ orJT
lo r: - odoaz ssij lo 9?
used to mature a crop after its application to the soil.
Such matters as the spacing of the furrows in orchard ir-
rigation, the length of run and the corresponding most
economical head of water to be used, frequency of applica-
tion are of vital interest to the success of an irrigation
scheme.
Again, we shall not be able to place on our
statute books more logical laws concerning the proper use
of water, or to enable our judges to render more satisfac-
tory decisions in water disputes, until we have gathered a
large amount of data, under properly controlled conditions,
relative to the behaviour of water when brought upon soils
for the production of crops.
The "duty of water" is a phrase which expresses
the relationship existing between a given quantity of water
and the area of land that it is made to serve. This amount
may vary between the wasteful application of water on pre-
pared lands in an unscientific way to the highly refined
experimental methods as used for instance in Southern Cali-
fornia, Where according to P. R. Adams "the water carried
has the exceptional agricultural value of one thousand dol-
lars per miner's inch."
.Hoe add bd- noJtd-jeolIgqa a*! isdlB qo-xo -3 oii^jsm orf
jci awoiiul arid- lo gnloflqs slid- a.s
gnlbnoqasiioo erfd' bna run lo xidgnal
iiqqB Ic vons/fpsil ^>9au ecf o-t isd-ow lo S
i na lo aasooua artt oi d-asiodnJ: Isd"iv lo
no 903lq el slc f s 9C r d"oit Ilsxie aw niBgA
B.C- laci^ol 9-io,it asioocf
Oi oct a93&i(t ' I00 Icfsn9 o* 10 ,/ied-j3w lo
ii aiv Ifdnxr ,39-d-yqaiJb rred-flw r;i anoi^Ioal) '
q isfenir ,, ed-sb lo
alloa fioqu drl^.uoid neilw is^sw lo i0oJ:VBii3G f arid-
.aco^o lo ncldojyfcotq siicf
aesaatqxe ifola'w safi'iriq B el " f is>;tsw lo
xod-Aw lo ^d-ld-iuawp 9vl3 s usswa-sc
-niiOBta aliffi .evioa oj 9.0 BHI ai dl d-erid- fcrtfil lo BSIS edd
-6'iq nc 'lodsw lo rioictBDlIqq'B l.olsJesw 3.ij n ocf V 1 - 07
bsiil9i TjIiisM 9fd o* -^sw bilid03ian0 JSB nl Bbasl fi
-iiaD aiedd-jyoS ni sooed'snl 10! t: . ; a .oond-sin Isduamiis.
W Slid''' 8BU3&A -S -"5 O* OOOS ai9U>Y ,BirftOl
lo e, :oldqsox9 9fct ari
la' 1 - aisi
4
It is therefore, in order to be more definite,
perhaps advisable to use the phrase "the reasonable water
requirements," which may be defined as "the use of that
.",'iat by e
quantity of water which represents good practice when the
character of the soil, topography of the land, value of
the water, crop and other economic conditions are taken
into consideration." It is in general that quantity of
water with which the average farmer should obtain the best
results without undue waste.
iJ.Cii an ir-
It is, of course, obvious that this quantity
cannot possibly be permanently fixed and must necessarily
vary not only with the physical and topographical condi-
tions under which the water is applied, but also upon the
economic conditions affecting the value of the water and
the resultant crop.
It may be expressed as the number of acres that
may be irrigated by a definite quantity of water, usually
a second foot or eusec, flowing continuously throughout
the irrigation season. The most "commonly used unit is.
however, the acre foot, which represents a volume of water
equivalent to a depth of one foot on an area of one acre.
The Gross Duty for an entire System is made up
, sdlrrilab siom sd od rtsbio ol t e-so'i9'rorid- ai dl
. :
arid" 1 ' as bsiillsb ac' . xioi.rfw ",aJn3rii3-_
lct nouw eoi^os-iq boog e^iiaasiqai 4o>nw tad-jaw lo ^i^nawp
3itf lo ijflqflisoqod 1 Iioe orfd 1 lo nsJoaisnp
t 3-iB anoint iDrroo olirtonooe isrlcto >HJS qoio ,'13-lsw orld"
lo ^d-id-iiewp ^snd- I.eisri93 at. 8,1 W " .nold-aisblerioc ochii
cf sxlit nisd-do blnca'a isnTifll ggaisva arid- xloitlw u'dlvf isdsw
sJr.'id: uB^io ewoivoo ,. saitfoo lo ,ai
n ctawrsi bns baxil Y-t ;i ' nsrism ' :9C i 9( ^ ^
-Ibnoc Ir;o.r:Iqj3 r isoqod- brus iBCie-jdq &tii dd"iw ^Ino don *^^ v
grid ncqu oalB dnd ,&9llqqjs ei 'isd^jsw edd 1 ifoliiw leJbru; aflold
bits 'iodBw arid lo saLav orld gnid-osllfl anoidibnoo olntoaooe
a 91 os lo iscL-jm ild a^ L . ^a oci -^JSK
dworf^wcirfd fclarrour ' ' -1 bncog-j a
, el ' . ' ' ' 'figxiii e
e.: - ; " ..... ;OS 3/ld t i::
a: --'-. ' . - :oiO 9..
of the net Duty and the Loss in transmission.
The net Duty represents the actual amount of
water delivered to the land and includes such losses as
that by evaporation, percolation and waste, in addition
to the actual amount that is absorbed by the plant.
The Gross Duty is the relation between the to-
tal irrigated area under the System and the amount of wa-
ter diverted from the source of supply. The factors that
influence the gross or entire duty of a Scheme are as
many and as varied as the conditions under which an ir-
rigation scheme operates. An attempt to summarize all
shown in the following table:
ni 3sod ailct bna 'tfsjQ $&n srld 1 lc
lo cfnifOffiB Lsirtos aJd- ed-rtsesiqsi Y*& cJ-grt sal
as a323oi rfox/a asiu/IonJL bns bnsl sifct od ba r i9vlle
nl t 3oasw bn& nolctBlooisq tnc.f.jjs'ioqsvo Tjcf d-
q 9.ci^ ^jcf bscfioads a I JailS driuoms isxjd'Ofl 9ilj
-ocf 9ilct ns8wd-sd noi^jsl.s r i 9.ci^ ax
lo drii/onfl 9ilct bnjs ^scfaYS erld-
91 IT .vlqqjLra lo 301003 8iW rrtorrl bect'isvib
3.3 o f i3 s.rteno^ B lo ^tub s-ildrie r io 03013
-ii HJS iJoirlw -isbrtL- anoicf Lbrioo sri^ as bei'-xsv aa b
nA .
'i 9rid- n nworfs
( ( OJ (Distribution
( (
(Factors ( . f , , (Quantity
( (Rainfall (Distrlt)ution
*
(which (
(Clear
(can be (Water (Fertilizing silt
( ( carried in suspension
(consid- (
( (Humidity
vered as ( (Wind movement
(fixed (Climate fgggg?& Irri _ ven quantity of
( ( ( gation Season
(Altitude
(Losses in (Seepage
(Storage (Evaporation
( ( (1. Distance from the
i i j. j-i i
( ( stream to the land
(Losses in ( (2. Soil through which
(Transmis- ( &l ( the ditch is built
( sion (S. Kinds of (Lined & Unlined
FACTORS
(Factors ( ( ( ditch (Cross Section
( (
INFLUEN-
(which ( (Canal
(Evaporation( Lateral
CING THE
(may be ( ( (Field ditch
DUTY OF
(modified" (Rotation or contin-
( ( ( uous use
WATER
(Irriga- (Method of applica-
( tion ( tion
( Practice (Head used
( ( (Waste water
(Length of run
(
(Cultiva- (Dry mulch
( tion (Ordinary cultivation
(Cover crop
( (Configuration of Surface
(Irrigable (Soil and subsoil
( lands (Reparation of the land
( (Ground water level
fcroos (Length of growing season
( (Diversified or not
V
(Factors (Faulty adjudication (Appropriation and granting
flnrl P.nm->+'. Hvi^avo I ~f _. _i_j j
( ( and Court Orders
(which (
(may be (
(cor- (methods of
( rected( payment
-_ rights to more water
( than is needed
(Based on quantity rate
(Based on flat rate
. -
'jtfaJ )
nc.~
tflH
Jlla gni. '
noianaqawa nl bslTrso )
'
*3tS
nac;
.
' ) 9 - flral - a ) baxil;
nc...
jiic r fl
>n.sl sHd- od" mBaid-e
rlpldw ilsi/ortrid- IloS.2)
j'll.acf al ilocfJ.fc srfcf )
^ bsniajlo afcnlA.5)
fi 3GC r iO) rfo-j-iJb )
Jnl .
c, } . a
riocMb Msf*)
-rrl^rtoo
9Bi/ S.U00 )
-BOilqqB 10 bofef8M)
no 1*. )
riolrlw) -ffaiLrattl
) )
) gcf vant) 3HT OHIO
10
H3TAW
no
10
rlolara
noJt*BvicMx;o Tjna
CO^O 13VOO)
)
90Bl'^;Jci
lloadua bna 1J
bnsi eil^ 1o noi a&niJl )
I9V91 19JJ8V. )
^c
..
* bna noxjfliiqo'f od-
) ) /
6s6 er
J-HB.C/P nc
i no .
All these factors do much to increase or de-
crease the area that may be served by a given quantity of
water. There remains, as a disturbing factor, the law
that the more water that is added to a crop, the smaller
will become the yield per unit of water served. This law
of increasing water cost raises the question of whether
the water should be used to obtain the largest possible
50 acre 'Inches 'Yield 'Total 'Price 'Grose ' t M.et
yield per acre or whether moderate quantities shall be
used to obtain the largest yield per acre foot of water
served.
There is a depth of water for each type of land,
crop and water conditions, which will provide a maximum
profit. When water is added to a greater or less extent
the amount of profit will vary accordingly. It is only
with an increase of our knowledge of the duty of water
that this point of "optimum" water, or of maximum benefici-
al use, can be determined for different crops and climatic
conditions.
The following example will illustrate this point
more clearly. (&)
A beet field is supplying beets to the factory
at a contract price of five dollars per ton. The total
cost of producing the crops, including interest on the in-
-01) 'jo sajsaionl: od rloim cfc 2 f otfOB'i 939110 1IA
lo ySlSttBUp nevig B ^d sviea ad ~am Jfliid
arid" .lodoBl gnidiLtfaib & a 3 . arciamei
r.e add" qoio B ci beabs ai d-BdJ isdav; siorci arid- d-jsifd"
elriT .&9visa isdsv; lo dir/xr isq blsl^ sifd 1 smooedllxv;
isrid-QjiIw lo noidae-up srld aoa'ifl'i daoo 'isd-BW giiiaaoionl "io
sidlsaoq dasgial sild- nlsdcfo od bsan sd bijjoxie isd-aw arid
sd IlBrfa seidid-nsup 3d\srisbom isrfd-aifv; 10
o dool 3-1 OB i aq blc-l^ d-asgiBl arid niadco od
Ic sq-od- doss iol lad-sr lo ddqsb B ai
irjjm'J:x.3fTi B abivciq IIi s ,v riolu'w t ano id Imc o tedaw br.a qoio
dnadxe aasl i-j isd-ssis a od bsibbs el isdav." neiiW .d-llo'iq
^Ino ai dl .YlsniE^eooa -^isv Uiw diloiq lo dm/orris add-
^^dsw lo ^d;/5 sr!d lo egbslworal IJLTO lo sasetonl ns rfdiw
-ioilsnsd murrixn-rr lo ^o ,iedsw "loxjircid-qo 11 lo dnioq siiid- dsad
oidamilo bnB aqoio dasisllxb c iol benxmisd-sb ed HBO , aexr IB
d;nioq aiad sdBid-sx/ili Iliw .:g gniwoliol
.
'i'cd-ofll arid od adssd s^- ;3 2 - t -A
ladod c .nod i9q o " --" 3 ;
-rti grid" nc ' ' ^^ C0
' 8
vestment, may be assumed to be thirty dollars per acre.
Tabler I may be then constructed on the basis of the crop
yield in the Utah experiments (see Bulletin 115, 116 and
117 Experiment Station) on the effect of varying quanti-
ties of water on the growth of crops.
50 acre
inches
applied
over
1
'inches 'Yield
'of wa- 'of
'ter on 'beets
'each 'per
acre 'acre
'(tons)
i
T"
Total 'Price
yield 'paid
of 'for
beets 'ton
(tons)'of
'beets
i
1
Gross
in-
come
from
beets
,
i
Cost
per
acre
: J
i
To- 'Net
tal 'in-
cost 'come
'from
'beets
i
llet
in-
come
from
acre
1 acre
r
30" '21.0
t
21 ' $5
i
|105
r
$60
i
$ 60' $45
i
$45
2 acres
3 acres
4 acres
i
15" '19.5
i
10" '18.6
i
7.5" '16.3
59 ' 5
i
56 ' 5
, i
65 ' 5
195
280
325
60
60
60
'i 1
120 ' 75
t
180 ' 100
c '
240' 85 '
37.50
33.33
21.25
Prom the above, it will be seen, that the largest net aggre-
gate income, was obtained when the 30 acre Inches were spread
over three acres. When spread over more or less land this
amount decreased. The largest profit per acre was obtained
with a thirty inch application, being seven and one-half dol-
lars above that with the fifteen inch application. In the
table the cost of the water has not been taken into account,
19 q 3i.3l lob 1*1 irf* 9tf o*. benttraea ad \;3;r; t
qoio 34* ID a laser end- so bsda/rliaxioo tterfcfr ecf .^sm I
baa 811 .311 aitellwH $aa) stfitemtiiaqxe dad-Li 9di at
Ic do ell 9 arid no AaoWa*3 ^nerfiittcqxa VII
Ic ddviroig arid 1 ac IS^BW lo 3-3 id-
-ftl' -Hi'
ante o
raoTtl'
9'tOB 1
smo o
moil'
ad29d'
T t~" ' '
lO'lfl
-at
9i ftOO
MOfl
i
I
T _.
! oa
03. 75 '
S'-'T
. j -j
3V ' 021 ' 03 ' 3GI
! ! I
' 082
001 ' 081
i i
3&.-.I2JL
08 ' .dSSS
.bxsq 1
2d99d
-A. -A
QS
83.
SO-
blalZ' ae/foj-il 1 si os OS
-JW-lo' asrlofii
T9d' 5DlIqqB
ric
9'J '
Q-IOJ3 I
"T
O.IS'
-;;_;!:
. - r
S| OS
8.8I j r
A^MLie..
3310JS 2
33-10B 5
a.9'i9a ^
Jan ctasaisl 3dd osncJ .ri^sa ad Xllw d~i <9vocfa arid 1
si 9 '.T aaxlonl 9'ioa OS eifd rt9riw banlsjcfo asw ,3i?too:
ild- brial aaal 10 siorn isvo bJ39iqa fiadtf .as^oa 99ic!cf -IQVO
asw 8'ioa-/i9q d-lloiq dassial 9rfT .ftdaaonosf) iiroras
-Io& llaxl-aao bits navsa 3ni9d ^nold-aoilqqB rloni' ^d-ix
.noWaolIqqa danl nse tiw d-arf* svodfi a-xsl
oini najiad need .ton a- i i r arid lo iaoo grid-
9
and the question of what is the maximum economical yield
will therefore be dependent on whether the surplus profit
of seven and one-half dollars will compensate for the cost
of the extra fifteen Inches of water applied. Similarly
in the fifteen and ten inches application, the maximum
economical duty will be decided on whether the surplus prof-
it of four dollars and thirteen cents will compensate for
the cost of the extra five inches of water applied.
The differences between the net duty, the water
requirement for maximum per acre yield and the water re-
quirement for maximum economical per acre yield, should
therefore be clearly kept in mind.
"The conect water requirement for maximum
per acre yield is that quantity of water
which is necessary to produce a maximum
yield per acre, when the losses of water
by percolation, evaporation and waste,
which can be controlled by skilful meth-
ods of irrigation and cultivation, have
been eliminated.
The water requirement for maximum econom-
ical yield from a limited water supply is
that quantity of water which correctly
used will give the maximum total net re-
turns from a limited water supply and is
dependent on the value of the water, the
value of the land, the cost of irrigating,
the cost of producing the crop and the
value of the crop. The net duty merely
represents the volume of water which is
used according to the available water sup-
ply, the judgment and the skill of the
blsJhj laointofloos ntoralxsm O al cMw 1o no id" as yp an r * frets
dlloiq siflq'iwa 9<id idddsiCw no dnefcnsqsfr eef diciatsd* llltr
daco arid 10! acUansqj-noo Illw a-islfofc llcii-eflo brt^ nsvsa lo
.>8ilqqs is* aw Is aaiioni nss^'iil eicfxa artt lo
m arid- t noWJ3olIqqs asrfoai ns* fons 0e*tll eiij nl
<yffl
'iol sd-sansqfttco II ivy scfneo aesd-'x brus sisllob ^wol lo Jl
.bsiXqqjB iscfsw lo assort! svil BI^XS sdd-.lo d-aos arid
arid .YJW& d3a sad-
i9d-xjw arid 5ns biai^
9-1 os i^q leoinrorroos mxBfiJtxam 10!
.nJt:.i nJt dqail \;Iis9lo acf
nujTilxfim lo'i d-n9m3 r ili/p9T: -ledsA' dooaoo
i?jsw lo \;didfiEwp datfd- ai blai^ S'loa
tixefii s 30i/I>oiq od ^saaeoon el
lo aesaol add nauw ,aioa taq fjlai\"
-cfcrem Iw'ilixa ^d bsllo-idnoo ad 0ao rfoirlw
avsil t
rt'f
~ '3 ':?"' : U Jt) .
flmll a notl &.
io Y ;i
.
ei bn ^laqws
ory .
'
. 319H1 .
II doJ
' ^ i
'
10
Irrigator. Where water Is cheap and
abundant throughout the irrigation
season, the net duty will often exceed
the water requirement for maximum per
acre yield, because the consequent low
price does not enforce careful irriga-
tion and cultivation methods. Where
water is scarce and therefore valuable,
which is the usual case for a great
part of the arid region, the net duty
will approach the correct water require-
ment for maximum total economic yield. "(>)
The amount of water that will produce the largest
per acre yield of a certain crop is by no means at any time
the most economic Duty. It becomes therefore imperative to
undertake sufficient experiments to obtain this information
for all the standard crops.
Theoretically, the aim in irrigation should be to
obtain the highest possible efficiency out of every inch of
rainfall and every supplementary acre inch of irrigation,
and to use the least amount of the latter necessary to main-
tain a favourable moisture content throughout the main part
of the growing season, while still permitting the soil to
dry out sufficiently to mature the crop. Irrigation should
be applied when the soil moisture content drops to near the
wilting point, and in just a sufficient amount to raise the
moisture content to the maximum usable water capacity of the
soil throughout the root zone.
bos qssifo al i
noWaai'rxi 9rfd d-jjoifcjjjciild- dnabaxjda
gsoxs hed-lo IlJw T#JJ6 don siid <noe392
isq nuralXBrtt ic'i driameiiwpsT: isdsw sdd
wo I dngupgonco arid 1 ascreoadF 5l9l^ eios
las ion secb
Jtd-evld-I.t/o fta
9rcl9 j i3f-d' brrfl
^; s -iol saeo lauaw sxit al
I9>iw d-osi'ioo eri* rfosoiqqa
olmonoos lactod" nLurnixsrn to'l
o'iq II lw -**dcr ted-aw lo d-ax/oms erJT
d-a arrasm on ^d a.t qoic nlad-ieo JB lo blsx^ 910.3 13 q
oj 9Vld-Bi6qiJt 9101919^ 39aoo9cf *I . ^ojjQ olmoaoos cfaont
airid nl^tcio o^ ^JHami^sqxs dt9ioJtllua gaiadi
.aqo r io bi3ijnBd'3 sxi-J
9d bli/oda noid-asliil nx ^is srid rtfllaoxc^oeriT
1p ;tuo YO9ii' 3t ' 1 slcfJtasoq daadaix; axid rtlflddo
lo rioni 9-ros ijiB^nsmel qq.ua ^isvs OHB ila'iriis'i
-nJtsm od" 11BE390S0 isdd-dl 1 9iid lo cto/ohta dsasl erld- oau
iiaq niaw. ri* Jijor^o^r^ Jnsdaco 9*ruJai'oio aldati)Vfll
od- lioa 9dS jjnijdiimtsq lllda ellrfw v i, gnlwois 9l:
blwoxia notd-esliil , .<JP'io add- etufBin od \ ' olllwe dwo -
9 {d ia9a. od sqoib dast^mo etwdaiaia II neriw
arid lo ^dlaaqao ts^aw o* *B^ftps aiwteion
r erJ :*!. lioe
11
Proper irrigation supplies a favourable moisture
condition and encourages the growth of feeding roots, bac-
terial activity, and the liberation of plant food. Im-
proper irrigation checks these processes and often causes
unfavourable soil temperature and drainage problems, or
the leaching of plant food. Proper irrigation tends to
produce optimum moisture content conditions. Again, there
is always a tendency under irrigation to compact the soil
and to exclude the air. It is exceedingly important , there-
fore, to practice rotation, including soil building crops
which will offset this tendency of the soil to compact and
make it practicable to maintain a high state of tilth with
a high percentage of organic matter. It is the intention
to discuss in this thesis these influences which may modify
the net JXity of water, rather than the many, varied and com-
plex factors, enumerated above, which go together to form
the Gross Duty of an Irrigation System.
That it is well worth our time to give careful
study and investigation to this particular phase of the
question is b orne out by the following general figures of
the disposal of irrigation water after its application to
the soil.
II
slcfaii/cvsl s asllqqi/e uoi3&% r ii
-oacf . a.j-001 anlbeol lo ifcj-woig 9i# aa.gBtucone 5ns
-ml .bool drialq lo aoirffliecfil 3rio l Jbae
nsi'io >n.3 aaaaeociq sasdd- a^ioado
9g^nJ:2i5 frna -3'fi/-j-ei3qnt3cf Iloa
nol-te5i r rti Taqo'rl .boo'i cfnalq lo
.snoid-Jtbnoo ^nsvincc siwctaiom miflRid'qo SOJJDO-ICV
Iloa siil dottqinoo oi xiol-tsali'il i^bnx/ ^onsDnad' . a a^jswla ai
^Ignlfiaeox-i al ctl .'xia arW ebuloxe ol >nB
Ilca ^riibji'Ioni tKoid'ScJ'oi soidosiq o;f .910!
.-? toaq.Ttoo od- Jioo 9;.{ j Ic ^onsSne^ aMd" d'ael'io IIlv? rlolxfw
lo 3d -Su d'oia. s n.a.jnicra oJ slcfao.ttooiq ctl s^lBfli
is-tril odj- ai ,tl .is^^sra olaagio lo ss*^ 60 ' 10 ^ ^gl^i J3
ifoiiiw ssonsullni assrll alasriit airi^ ni adooaio oct
moo .bna JjsJ-rjBVi^msm e^Ict naa^ isactei t r i3t9\7 ic ^jwd-'^sn d^
tiriol ol i^ii 330.1 og iicl'flw .. 9voo^ Jb3o oisnujns ta^ipd'os'i xalq
.:9^aY2 nolcrasi^nl ne 'lo ^ud aaoiD srlci
liria'iao svi^ oo' & (:!* 11/0 [^*iow Ilsw al .^1 **lT
srf* lo easrlq islsjQlitaq airfj- od 1 rcol-tngi739vni >as
*.- ' ' -7
lo ssiw^il laisnas si^lw'ollol 9^ orrio cf ei ricW
od 1 noid'sollviqs adi ^ectla isdaw . -ri lo laaoqalJD
.a
12
Surface waste 5- -15 percent
Deep percolation losses 20--50
Soil evaporation 10--20
Total " S5--85 "
Amount available for
plant transpiration 65--15
It will be seen that even under the best of conditions,
the losses will usually amount to thirty-five percent of
the water applied.
"While these losses appear high and while
they can be reduced under proper methods
of irrigation, the expense of their re-
duction may, in many localities, exceed
the present value of the water saved.
Where the losses are excessive, the best
crops are usually not secured and it will
pay to improve the method used and reduce
the losses to reasonable amounts, "
Whilst it is unquestionable that the major part
of this loss is due rather to the mechanical factors of
the application of the water to the landfactors which
even under the very best of conditions are often not prac-
ticable to modify a greatly increased efficiency of the
water should be obtained from a proper knowledge of the
more theoretical considerations of the question. It is
rather with this part of the problem to which this discus-
sion will be limited. Any improvement on the practical
21
jrreoisq SI 2 sctss?/
03- -OS aaeacl col;*J8lqojsq qegtl
QS OI noid-3'oqsv9 Iio3
38- -32
51 --co
,aao loir-no c "io craed Silct -isjsm/ nevs
"to ^nooiLi vll-\d'-ix;:fd' o~ ^xu/oma
ici D^cfsllayje tauiom
fioi^/Jtlqana r ict j-fislq
ness sd II lw d~x
IIlw -aoaaoi sdcfr
ell.iw
afcon/sw
-o-i 'li
aaaaol
io
Iliw
<
9 c iii saeaol aiij e'i.
Liw f>o c iwos.fcj ton ^Il3.ua;; '913 aqoio
I>nB bsau ho;iy&m Siitf avoiquti p^ x
o^ asasol
lo
a r tcoOB'l--f)ruI srW o-l
xq uO0 ns-Jlo SIB aitold-lBiic
* lo ^oneioills fosaasioci
lo s;^I)9iwonji igqciq a
ewb a.t aaol airict 'Io
lo noWfioilqqs srid-
nsve
ai \t no Ji j 2 9 l. f p 9ilo o QfiC
u* rfo!4 od- msldoiq a
SIOQflj
sq aMcf rCcfiw
9JliKil sd Iliw coia
13
side is an entire local question, to be solved by each
individual project according to the prevailing conditions,
A discussion of this side of the question could at the
very best only be most indefinite. On the other hand
theoretical considerations lead to definite principles
which if followed expeditiously should help to secure not
only a higher increased Duty on existing schemes, but al-
so give much more definite information as to the probable
irrigable area under a projected scheme.
rioss TO' bavioa od od" t nol;ra9up laoql atlctna B si
9-cW o* p i63(,oiq
MX/CO noid'asi/p 9ji* lo s&la aiitt lo Hc
tsrSto sif^ nO .stinllsbni *aom ad Tjlno cfaecf -^
beal anoictB^sfiisnoo Isold'9 > '
ten sijjosa o^ ql.ri bIifOB'3 ^awoWlfisq^s bewollol li
-Is cl-t/d t astaeiloa 3ni--tax>:e no Y*^ baafleioni isrigM a
9iCct o* as xiold-sfmolxil acHnll-^b siosi ilown svig os
s r i >s
14
CHAPTER II
. - i <*'..% vvr i rc, v>- . J , > * 7< "-' .-.. r- T ' -. * f-
THE TEXTURE AND STRUCTURE OF THE SOIL
It is now perhaps universally recognized that
the character of the soil has more influence upon the Duty
of water, in the sense of the reasonable water requirement,
than any other factor. It is the texture and structure of
the soil which to a large extent determines the amount of
water that is lost by deep percolation, carrying with it
below the root zone a considerable amount of valuable plant
food. It is also the texture and structure of the soil
which determines the lateral movement of the water for equal
distribution under furrow irrigation, as well as the upward
movement with its consequent evaporation. A brief survey of
some of the importance characteristics of soils will help in
obtaining a clearer perspective of the various influences to
which irrigation water is subjected. Arbitrarily speaking,
soils may be divided into seven grades or "separates", com-
'-'"--; i ' - "X . .
prising fine gravel, coarse sand, medium sand, fine sand,
very fine sand, silt and clay. This grouping, established
by the United States Bureau of Soils, is dependent on the
size or tecture of the soil particles, varying from 2 1 mms.
in diameter for fine gravel to diameters below .005 mms. for
clay.
II
lo
"10
cf-1
JIGS 3H1
ld- beslnnoosi -\jIlBai3 vim/ aqsitaaq won al d 1 !
^d-wCI arid- noq> soaewllnjt a'xora BBC! lioa srfd- lo
3idBnoajS9Tc &d3 lo eartsa exio nl i9ctaw lo
iudxscf srij- ai *I .lod-oal isacto Y^B aadcf
sill a9nlw9*efc J-JisJze s^isi s otf rlolrivr lioa sad-
qeeb ^cf tfsol. al rfsrld- r i^-3v/
a snos d-ooi add 1 wolod
lioa 5:id lo 3'i.udoxnd-e Jbn-c 9i.ad;x8d- sifd- oals ai .i>coi
tol T9d-.3w slid- io d-nsmsvom Isisd-sl eif* asnim-isd-sb foiil\v
i; 3/ict as Ilav
lc Y9\nua Isiid A
ni qisri Iliw alio^ lc
oct aaonswllni awclisv erid- lo 9Vjd-o3
..^niaiaaqa ^Il'ia-itlcTiA .bs^oaccfi/a ai -tdd-s-J iroW33Ttl xfolri*
-moo ^'as'ts-ieqaa" 10 asbBta nsvse od-ni bscivlp sd Tfsrr silos
.&JXSB anil bnB3 miribsftt .,bnjaa saiBOO ,l9VBis snil tin
' JXla *&rt*e snn
v;o f i r ii;'i
90C08d--ioqmi add 'ic srrtoa
rto
a,Tjr t 1 2 moil
10!
ei ,
lo
f air
ull
15
As these groups vary in size they exhibit
properties, especially in regard to the moisture content,
which vary widely, which again are imparted to the soil
V 1 ,.\ ;-'--- f", '' , <~
of which they are members.
These clay particles are very minute, jagged and
angular in outline. They are highly plastic, and when
rubbed together become sticky and impervious. They shrink
on drying and re-expand on being melted. The finer part
of the clay consists of colloids, which, because of their
fineness of division, exhibit certain well defined proper-
ties, of which absorption of moisture and high plasicity
and cohesion are the most important. Silt exhibits the
V' ' ; i <; '. 'i .: ':'
same qualities, but to a much less marked extent. The
presence of clay imparts to it a heavy texture, with a ten-
dency to very slow water and air movement. Its water hold-
ing capacity is high. The soil is highly plastic, becomes
sticky when too wet and hard and cloddy when too dry.
The sands and the gravels function more as separ-
ate particles. They are irregular and rounded, exhibit
very low plasticity and cohesion and as a consequence are
little Influenced by changes in water content. Their water
holding capacity is low, and because of the large individual
size of the pore space the passage of water is rapid. In
esia at Y
<*ri9;tiioo siirtaiom ertf o*
Iloa* eil* o* b3*-ieqmi 9ifi
-blorl
fens oi^afilq
aquoig saarf* sA
nl ^Ilaxoeqas <ss W
riolrfw ,^Isbiw Ytav
i arts
cl
4
T-'il 3iH' .&9-tls>^
55flll9l> ilow ftJ
rigirl barf sv'
:S
1*3 9:TfCO
no im.3qx-9*x bita sptTtb
*idMx <ftoalvxb lo a a or, on il
'io nox*qio8cfs doJWj? lo .331*
11-',?^ 3281 ilojjra s o* *trcf ,aax*ll30p rstea
1-^ , 9itr*X9* Y^ 3 1 '' B '-'"^ ;:! ' s*%eq;ftl ^slo lo eonsao'iq
3'/r 3*1 .*ri3ittevcni ils bit-? ie*BW wola TJTTSV o*
.oWasIq ^I;.i3^I ax ixcs sdT .dslii'a.i . 5
t risriw T ^bbolo Jbfls 5*iBi{ bite *9tf oo*
o'iofn noiioayl alaivsig sxi* 5xis abrtsa 9d
wo I vi-sv
eX**ii
9on9.vpsanoo B 32 bne aolas
ilsiIT .*nad-n:oo is^sw at
16
regard to structure-- or the arrangement of the soil par-
ticles in the soil--a wide variance is met as well.
It is a well known fact that the soil particles
are not homogeneous in size; neither do all the particles
function as simple grains , being gathered together in
groups called granules or crumb structure. A small particle
of soil may be made up of a number of very small grains
placed in between somewhat larger particles, resulting in a
reduction of the pore space. A soil having such restricted
pore space is said to be in a puddled condition. The condi-
tion is detrimental to plant growth, impeding the root de-
velopment, but also preventing the circulation of air and
water; a most necessary function for plant growth.
On the other hand, when a soil is made up of com-
plexes of soil granules an increased pore space will occur.
There will therefore be a very wide ranpe of pore space rang-
ing for the different types of soils as shown by Table II.
Ixoa ertt lo ^nanissnsiis arl* io--s r ii/o o.uid-3 o;t 13391
tf as d-3iK al sonslisv sblw js--lioa s-ctt ni ee
Xloa srict cterfcf d-osi riworui llov/ e al d"i
exld IX s oi> iferWisn ^e^ia 1 a.uosnsBpmori cton
nl i9d*9aod- Bs'isrictag ^iiierJ aixisi^ slqinls aa nol^
q Il^i'ta A " .0'iwd-o.tn ia cfnujio r io asiynsig Jjsli.30 jqijoig
salaia Ilyiaa Y'^sv lo 'iscfnwa a lo qw bam scf ^sm XI oj 'io
B ni yj!iit/33 r i t 33loid't:Jq is^iBi cJ-eiiwsmca noswct-ad ni b^o^iq
fis^oii^ae^ doi/a -uilv-ui lie 2 ..t .SOBOB 9ioq srtt io noJ
l>noo oiTI' .ncinifjnoo boXM)jJc s nl sd o* biea a I 9-0 aq a 8-ioq
-8b d-co'i 3iicf ^il&sqrai ,Tl*woi-^ itrwlq oi Xa^ng^l'id-ob a I
bna iii io nol,-t.ai00TJ.o. e:i^ 3fil*rj9V9iq oaXa ^twcf ^^nam
.rld-vroi^ :trt>3lq -iol noi*oitJ/i Y 1 ^ aasosxi ^- M s l^ 9
-;uoo lo qjj 9&o.E al iica B nsrlw ,nsi isrid-o arid n-u
.T:.UOOO XXI. v aosqe 9ioq tsa^a-ionl HB aaXi/nais lioa i
soaqa yioq io 9-;,ftfli afcl'w ^sv a 9tf ' sip'lsisri* XXlw
.IX aXdai' ^d nwoiia aa aXioa lo asq"^* dnsialllt) 9.1;
17
TABLE II nt.
Percentage of Pore Space for Different Soils
(King)
Sandy soil 52.49
Loam 54.49
Heavy loam 44.15
Loamy clay soil 45.52
Clay loam 47.10
Clay 48.00
Very fine clay 52.94
The pore space in any of these soils is natural-
ly subject to considerable fluctuation, especially in the
surface soil, due to tillage and the amount of organic
matter present. When, however, soils are in the physical
.iota lr..ar<st*fcd grant: *-,- :icu. " &ac -'-.:oe tin
condition for the best plant growth, it will be found
that the finer the soil, the greater will be the pore
space.
In a soil the pore space is occupied by water
and air. If the water content is low, the pore space is
large and vice versa. Thus the relationship of the aggre-
gate pore space and the size of the individual spaces to
the amount of contained air and water, to their movement
through the soil, to root extension, to soil aeration, to
II iLldAT
ic -1. eo
Gi-.SS 11 o a
e&.i'S
51 - KU501
33;G 1X02 'J8lQ
01 . V msol
00.3^
. 9S9i-:d- lo V*' 1 ^
- nl ^ll.-.lo^i-.cis ..ni: I.t3u.-foi;_l slcfe'is^i^noo c* d-03{,cf0a ^1
oJfisri'to lo .-i-nucra;?. silvt OHB 9 -3.8 111.* o" .swb txJ:o5 eoBl'i/js
i^v;Tc D-" ni 01^ slxoa fi3V9 r crr , ne^iW .^naagtq Ta^J-^jtr
onu-l scf ill.*- -ti .^.vo'i^ d-Hslq ctaed at TOI noi^lcnoo
is TB/f -;cf balquooo w.c 3C3qs stoq arid- llc^ s ni
ai 90-cj 9'ioq adj t wol ai J-ns^noo i9*a-w siicf II .-lie D^
133^ e.^ f lo qiriarscWalsi arf^ eucfT .sai^v DO!V bc^f s^'i-
o* aaoaqa Lat&tvttnl srtt lo daJa 9iJ bns eoaqi: 9-100
svom ilgiicf oct ^is-lsjif ixct? iJts b.sol s-i no r:
.rtoId-siaB lioa o^ ,nolsrt9jjt; ^001 oJ ,llo,;
18
bacterial activity become apparent.
The factors which control the soil structure
are plasticity and cohesion. As these increase, there
is. with an excess of water, a tendency towards puddling.
Oh the other hand, when too dry clodding will result. 'A
diminution of these factors in heavy soils will give a
better granulation of the soil particles.
Granulation is "nothing more or less than a
condition brought about by the force exerted by a variable
water film and the pulling and binding capacities of col-
loidal matter, operating at numberless localized foci. It
is evident that any influence or change in the soil which
will cause a greater localization of these forces v/ill pro-
mote increased granulation." And since the optimum moisture
condition of a soil for tillage is also fortunately the op-
timum condition for plant growth, careful attention should
be paid to the effect of alternate wetting and drying of the
soil, ploughing, freezing and thawing, and the addition of
organic matter and lime, upon the granulation of the soil
particles.
The moisture contained in the soil may be hygro-
scopic, capillary and gravitational. Hygroscopic moisture
is the moisture which a soil dried by artificial heat will
81
snoosd ^cMvj-^ofi laliectocd
'S lice erlj Ici^aop rlelrlw a-iotfojel snT
saje'ionl s^aii* sA .nclaerlco bits Y^-^-^BBlq 9is
abiewoci Y 3 ^ 9 - - " 9 ^ 8 is*aw lo aascxo ns riiiw .3!
A' .^Iwas-r jil-w grijb>clo Y*I^ cod" asdw , firxsrf isn'^c 9r& nO
a BV 1% liJtw aiioa ^vesa ni aic^osl sascid' lo rtolJwnJtfaib
. :;9lol.iisq lios exit lo no Id- si was 135 isJiscf
s rxB/iT aa?i -T:C 9 r rcin j^nliid'c
lcfalisv -3 ^cf te^iexe aoicl srfd-
-Ico lc a-:'i^iojsc30 jjnibxil-:- br.a
l .loci I)9slleocl 8asi c i3CJnwn
;Ioxa.v Uou srit al s^nsrio 10
al
ed* bas mill 'io^aw
..'is
Jaxtf JneoiV3 ai
IIlv; ^Vc
91-ucJ-sicfr. ffu/.Tiioqo ori^ on>u brtA tv .nolj lortBig baaBe'-ioni gj-om
-qo Oil* ^i9.t3niKHol odla cil as-- 1 - 1 ^^ lol Iloa fl lo noictlbfjoo
biwoas fiol^froJ^s iL-lsT-'O <ii^v/ci3. Jnslq iol nolJlbnoo mi/mlct
9ii* lo 3niY*xo i> B snlJiav/ 9d-oms^i lo tfoel'le srfv cd" blsc ac?
lc ncl^lbba 9iIJ boe t get 1 wad* boa gnisseil . ^clils^olq
I lea oiIJ lo floijolirnana arid noqjj 1 9 ml I bna
ni
f i bas
,olqo-oa
IIlw
rfelilv? a^ ' ;n srfj a
19
absorb from a saturated atmosphere. Due to the absorptive
capacity of the soil particles, this moisture will exist
round the particles in the form of a thin film, being held
partly by the surface tension of the film and partly by
the molecular attraction of the moisture molecules. The
amount of hygroscopic moisture increases with the total
surface exposed or the fineness of the particles. Any
practice that will increase the colloidal materialthe
humous, colloids being very susceptible to an increase--
the higher will be the percentage of hygroscopic moisutre.
This is well illustrated in Table III.
TABLE III
Hygroscopic Capacity of Various Soils
Soil Percent clay Hygroscopic
remaining in Water ex-
suspension pressed in
after stand- percent
ing 24 hours
15 clays
7 clay loams
9 loams
5 sandy loams
4 sands
Hygroscopic water is held so rigidly to the soil particle
that it is in no way available to the plant. As this zone
51.97
10.45
17.15
6.06
12.06
5.18
7.39
2.50
2.95
2.21
61
IX iw
Mar! gniscf ,itiin ni
aidft a9l
a Tto raicl ed^" a
,cfa
'qj
eoaliua sxlct
sdtf lc eaensctil sxl* 10 foasoqxs
iBoioIIoo add" easeionl IlJt* <tfijrf^
aa o3 eldid-qsoai/E Y^ev iolloo ^aoorritrxl
iri oJ:qooco'ig^fi lo eafi^nsoieq c- XII.', 1 taxlglrl orf.^
.lli-oldisT nl i>e^B^jj!Il Hew si alriT
III 3JHAT
al
ni
S&.OI
VS. IS
80. 3
31.71
81. 5
50.21
06 . 2
es.v
aruaol c i
vjhn&& S
-
.
encs a
20
increases, due to an increase in the moisture content, a
thickness of moisture film is reached in which the molecu-
lar movement is perfectly free and unimpeded. These two
zones, one in which capillary movement is more or less
free, and the other a comparatively thin film in which molec-
ular movement keeps the moisture attached to the soil parti-
cle, gradually merge into one another.
As more water is added and the film thickness
round the soil grains, the outer layers are held with de-
creasing force, and a point is reached at which plants are
able to procure all the moisture needed. At this point, ac-
cording to Dr. Widtsoe, the film water is held so loosely
that it moves freely from soil particle to soil particle,
being termed the Lento capillary point. Above this point the
water is readily available to plants and constitutes the
main supply of water for plants under irrigated conditions.
Hence the following coefficients are well estab-
lished (1) The hygroscopic coefficient is the percent of
moisture, based on the dry weight of a soil, that a dry soil
will absorb when placed in a saturated atmosphere. (2) The
wilting coefficient is the percent of moisture, based on the
dry weight of the soil, which remains in the soil when the
plant has reached a condition of permanent wilting.
OS
JB tCJTxeJaoo e r u>ueom s
-iroslom 90* doidw xsl
ai
ctfct 9E9iiT .babsqmifttf bne
33 si 10 eiom al .tasraevora ~.
oolo.il ifoiriw ni rrdl'l nidi ^Isvld'flijsqsaoo *
a sri.t od- 591103*^3 s^i^taioat edi
snc oc?:'. f .
r. no
raiol^* mill w bfi bebfcB ai .
-o> rliis filsxf 9iB aiSTje-t 10*00 9^
9 r u8 ao'itslq rlola'v,' d-a fiaflo^
oa <ctnioq aii .bsfcsan
oa fcisu c.1 --lod-fiw ralll silct t eot-
e Hoc; oct slol^i.yq Iloa mc'il
,*nloq xxIIiqa-
art* asuijj-ld-sfioo bfiJB sJoBlq o* sld-
Haw 91 s
1o *nsDT-9q srW si
Iloa Y* 3 ^ s cted* ,.Iloe
aiffi ^2) .etsdqaoatfs
an'* no bassd ,
s.d- nsdw Ilo
suall
iw dioao'a
s/wway Me &rmj of wa'
J J t t 1. J I *
a4 f *"
f ? '
21
For successful plant growth, the moisture con-
tent should never be allowed to approach the wilting coef-
ficient. According to the researches of Briggs and Shantz
the hygroscopic coefficient is about .68 as great as the
wilting coefficient or the wilting coefficient is about
1.50 times the hygroscopic coefficient.
The finer the texture of a soil, the greater is
the number of angles between the particles in which a film
of capillary water may be held; also, the actual amount of
surface exposed by the particles is immensely larger than
in a coarse soil. Due to these two conditions a soil of
fine texture will contain considerably more capillary water
than one of which the texture is coarse. See Fig. I.
The structure of the soil, or the arrangement of
the particles, will become a factor in the capillary capaci-
ty in so far as it affects the amount of surface exposed to
capillary action. Hence the granulation of a clay soil, by
producing a crumb structure and by increasing the exposed
surface, tends to increase its water holding capacity. On
the other hand the compacting of a sand, by increasing both
the effective surface as well as increasing the possible
number of angles for capillary concentration, will have the
same effect. See Fig. II. Organic matter has a great capil-
-
19V3H f.
.ta<
j JB 3.
. 3u 3LCT
i Sii 3<
o jt.i"jacf
aJ:
,i/rifl f i^
fc l
22
lary capacity. Not only its porosity but also its col-
loidal content exerts a very high affinity for capillary
water.
Capillary water moves from a wetter or thicker
moisture film to a drier or thinner water film. The water
will rise to a greater height on a fine textured soil tham
on a coarse textured soil, although its rate of progress
is much greater in the latter. Lyon and Pippin give the
following Table.
TABLE IV
Capillary Rise in Inches for Different Lengths of Time/^/
1
Soil |$ hr
1 hr
1
2 hrs
r
1 day
3 days
3 days
13
days
19
days
Silt and
very fine '
sand '2.7
i
4.7
7.0
20.0
30.0
45.0
52.0
56.0
Very fine '
sand '7.6
i
10.0
12.4
21.0
23.0
26.0
27.5
28.5
Pine sand '9.0
i
9.5
10.0
11.6
13.0
14.3
15.2
16.0
Coarse "
and medi- '
urn sand '5.8
i
6.0
6.3
7.5
9.0
10.0
11.5
t
12.5
Fine
gravel '4.0
i
5.0
5.3
i
6.4
I
8.0
9.0
10.0
10.8
22
'
Id" j'o
fl moi aevora
siiT .mill iecfw isaniffi
tf Iloa bsi-t-'^xscf- . anil a rtc d-rigJ
o s
ori* 9V I? n
&HG
'
! _. ~A rfr *^ riff v , -f '-
LljD I! Ou nXJ.il 3 j.jJJ i.j.vm
tecfrfiaia s oct sell. II iw
3 JDSIJJ^X' S fiO
axi^ ni i: si
vi
r~ ~r~ ~r~
T r c* PI r *T ^ * i
' 1 "
eiy siy ;
-T ' ' - !
1 1
,
T i 1
o.aa'o.s o.oe 0.02' a. 1
i i
,.V2 : 0. 0. 0.
1 s.^i ' o.5i e.ii' o.oi
r r ' r o r
O Ui
: t
8.0 O.OI'
I !
i
: e- 3V
-.3 a
. srtl^I
11 9313OO
1 -J.b9.T-
25
With a further increase in the water content, a point
will be reached when new additions of water will simply
slide off the existing film and be drawn off by gravity.
Dr. Widtsoe has called this point the point of maximum
capillary capacity. Any existing water above this is
termed Gravitational water. See Pig. III. It moves
slowly downward through the pores and tubes of the soil
until it is all absorbed by the lower drier soil or until
it communicates with the standing water table. When gravi-
tational water begins to appear, an adverse condition to
plant growth is obtained. The proper aeration oi the soil
is much hampered, the roots are deprived of their oxygen
and toxic materials tend to accumulate. It is therefore
evident that there must be some moisture condition in a
soil which is best for the development of the plants, of-
ten termed the optimum content.
i
The total range of available moisture does not
of course represent this condition. In practice the mois-
ture content will fluctuate considerably, forty to sixty
percent of the pore space being considered essential for
best growing conditions. It should be the object of every
irrigator to apply just such an amount of water to his
land as to bring the water moisture content as high as
ijcf lie nweib sd bit
lo tfaioq 9tt ctnloq al.:. - .
2! alc'd" svcda. lod-sw ariirfeJbcs -fiA .^'
aavom d 1 ! ..Ill .3!^ S>oQ .lajsw IB;.
lloa arid" lc aecfjjd- bits ESIOG aifct r^i
10 lisa isi'iib lewcl szi-i T c^ & -
ns-iW .olc r -d- iQ.ja-w ^nibnBd-a sr'j i
o^ noi-libnco siiovfoB rte ,iiiaqqs od" Bf..'
Ixoa 9t(- lo' nold-a'-isfi nsqc'io adT . L
x^ild" lc bexrl-iCjOi) .9*1.3 e^ooi 8u
iaiW ax il .ed--yrtuJ03^ o* &nsi
B nl nci^ib'floo sii/^aio^ emoa acf cfairm
- r lo t 8-*oslq sad' lo
alorit .9il^ eoitosiq al .nol-jibnco
^txls oi ^*io't t ^IdJ3T9blaffoa *^-
sol I ' . ,aa 5'.
as tfsJuI aa ctna
24
possible without experiencing deep percolation losses,
and at such periods that the minimum water content just
before irrigation does not approach the wilting coeffici-
ent. The extent to which this is achieved in practice is
illustrated by the experiments of P. R. Adams on Sacramento
Valley Soils. Fig. IV shows the percentages of soil mois-
ture in a fine sandy loam soil before and after irrigation
for various depths. The diagram showsthat the moisture
percentage reached or closely approached the wilting
point in the upper three feet of soil before each irriga-
tion, but that it was well above the wilting point through-
out the season in the third, fourth and fifth feet below
the surface.
The results of a considerable number of experi-
ments conducted on the moisture properties of soils under
field conditions of irrigation are summarized in Table V.
3 i
lo aa
/y fj'9il
-
wol9c r cfsol rfctll'i
3 1C
;u aiic-i
25
TABLE V
Character of soil
Usual ave
rage percent
of total moisture
i
At wilt-
ing point
i
When irriga-
tion is de-
sirable
\
After irriga-
tion when free
to drain
""
Sandy soil
, |
3 ^
,
5
8
Sandy loam
5
9
13
Pine sandy loam
6 ^
12
18
Loam
8
14
21
Silt loam
10
16
22
Light clay loam
? 13
17
22
Clay loam
14
18
22
Heavy clay loam
16
19
23
Clay
18
20
24
It is evident that, even after a heavy irrigation, the aver-
. ; j * . rr.ted cenc^ ttcn, the fl^'-d
age percentage of water held in a soil to a depth of ten
feet is far below the maximum capillary water content. In-
variably only the top foot or often the top layer contains
that quantity. With increasing depth, there is invariably
a decrease in moisture content until about eight to fifteen
feet, it is very little above the point of slow capillary
52
v au
9lird-aiQ.n Isd-oS lo drigo-raq as^iavs lawsU
HOB lO 13^O r I
. i i
-s^iitl TscfXA 1 -sgliil nsrfW 1 -ollw dA 1
9911 nadir rtoW 1 -afi si iiolJ-' taioq gal 1
jBtB'jS oc? 1 9lcfsila'
> '
8 ' - S '
! 1 '
-Iloa ^f)ns3
SI ' 9 '
i
ttisol ^foasS
81 ' d ]
niaol ^brtas snl'i
12 '*!'&'
i i
ntsoJ
22 ' 01 '
,
01001 " i3
1 ' Gl '
i . '
ms o I '^ o 1 o drfg IvI
22 GI *!
aisol Tjal'J
' 91 SI
1 . !
OTBOl ^SlO YVJ 39 ^
2 02 ' 81
;
^jgXO
-lave arfct . ncl^s?;! ill /V-sSil B isdls navs ,:
Kaxid' dTi5)lV9 si SI
119 j 'lo iiJcisb s od lioi. is rsl 5l9l ifd-aw
le aqacfneo-ieq 930
-nl. .dnsstnoo -ladsw -^filliqjso mi/^lxsc: 9d3
wo led i.sl al d^ss'i
10 crcol qod"
si
esdIJ:! od- drig-ts d-ycdfl IWtti/ ^elota ni aaasto^b a
26
TABLE VI
Table showing; the distribution of moisture after irrigation
(Widtsoe)
Depth
Depth
of Water
Applied
In the Spring
7.5 inches
5 inches
2.5 inches
1
25.80 '
'
-
23.56
18.57
18.42
2
21.88
20.73
13.81
17.49
3
20.17
i
19.09
13.53
15.65
4
17.72
17.84
13.46
14.07
5
15.91
16.29
12.32
13.98
6
14.55
15.83
11.81
13.14
7
14.21
15.60
12.31
13.26
8
14.15
14.81
12.70
12.93
Dr. Widtsoe has termed the percentage of moisture held in
field soils to a depth of eight to ten feet, with the top
foot in a saturated condition, the field water capacity of
a soil. In general it has been found that it does not
vary very much from the optimum water content for plant
growth. For various soils Dr. Widtsoe gives the following
values.
iv
,** ^ HI ; tolLV* ,.*.. 10 XH
{
SoFf"37v !
06. 52 |
1
1 3 .2 1 aa.'ioni 5' s^
! ' '
V3.U1 ' 55.52 '
-. i '
13. Si ' 5V. C-
i i '
83.12 '
2
,T3 y r i
GO.G-i. OG.^jj. WU.i
VI. 02
t
5
VO.M ; 9^.51 ; 8. VI |
2?. vi ;
*
86. ol So. 31 ' b2.c_ !
.1 i
xe.51 '
5
1.81 -11 58.61 '
i
53. M ;
6
&2.51 Ii.21 ! . OS. 51
1S.M |
^
.21 IS.M
:
51. M
8
lo e^^^aeo-ioq 9iW beifirrai a.ari
gild- Ml:. *9dl nsd- ccT juals lo dtfqab oct dlloe blsii
lo iccJ-ioaqso i-?*aw blaJt'l sxfct t na&ifcnQO bs^Bi^sa B nl docl
don aacb cM tfartj fcnwcl nasd aBii dl Isisasg nl .Lion a
gniwollol arW asvlg eoarffilf .-tO. slioa p^oliov io r d .rid 1 wots
.ae.yl.av
27
Soil to a depth
of 8 feet
Field water capacity
expressed as a per-
cent by weight
i
'Registered moisture
'percent by w eight on
'the basis of forty
'to sixty percent
'moisture content and
'thirty percent pore
'space
i
Clay
19
i
1 1625
i
Clay loam
18
1 9.414
Loam
t
1617
1 913
i
Sandy loam
14.5
' 1015
i
Very sandy loam
14
1 710
i
" ' -. J- - 1
no d-ilgis # vcf JKso-ioq' -i&q,
^cf'ic'i 1o elascf s^tf 1
ctnsoisci YJ"- 51 -* 3 Q^
brt.'^ cfnscirioo oiw^siorn
3 i>Ci d'iisot^ 1 ^ ^lirW
i
I
iqjgo istfsw'&.XeJre ' dd-qsl
i . . /CO
^3- : - '
i
i
> a otf Iio2
d-901 8 lo
62--31
i
i
e-x t-
5101
1
01 --?
1
T
ex '
i
81
i .
-i r -i r 1
vl 91
!
3.M
-1 ' ITtBOl
1
meol Y 3 -^ 1 ^
rrtsci '-^bnaS
28
CHAPTER III
THE CLIMATE
The first factor, influencing the net Duty of
water, that will be considered is the Climate under which
irrigation takes place.
The annual precipitation and its seasonal dis-
tribution, together with the temperature, humidity and
wind movements, have a very marked and evident effect up-
on the amount of water required for crop product! on, length
of irrigation season and the number of irrigations that
are applied.
The climate .affects not only the total seasonal
duty but is also mainly instrumental in determining the
actual monthly distribution of the water requirement- -a
most vital factor to be considered in the design of the
distribution system. The monthly requirements are con-
trolled by the crops grown and the locality under consider-
ation. Alfalfa or pasture in any arid region usually re-
'.$:r *.tfc c: . gg - -:-'*
quires water throughout the growing season, or from early
spring until late autumn, while a grain crop requires water
during not more than the first half or two- thirds of the
season. Potatoes require water throughout the season, but
Ill H221AHO
io ^cfoa 3s>tt 6i& BnionsJJlnx tiocroe cE-i 9dT
oJsfltlXO add 1 ' aJ. bsisbienoo 0d ^
lb lanoaaDe ad-x ba,- nolt.d-iqiog-ic Lsaaaa
bns ^d-iJbitrujii sijjctaioqnis^ sdd- .Ictivr nsddsaoJ- ,nold-ucfJtid
)C--iq qcio 'icl bs-iiupsi 'isd-.aw lo dm;o::u3 sd, "no
J-3iId- aaol-J33ii r ix Io -iscifta/n sricr bna aoasaa nolJagjrcii lo
..bellqqa
edi ^Xo tort ilool'l'-i
nx Ijed-rriiiiui
3d-3Tr sxl.t Io
srio lo iigiasb sr{j nx bs-isblenoo ad o?- 10 Jo/si
-noo 91 ' acfneKisrriifpa'i Ylrd-noa\ aixiT .fn&d-e^e noict'JJcf
TC3i)ianoo i?baw -^liapcl sxld bus nvfo'i^ aqoio sii^ ^'cf ball
-91 vLL&u&u noxriai blifi ^os ai a r rwaaq 10 s'lIfillA .aoiJa
10 .noasaa 30 .twig 84* ^wodsiioi'rid- tsd-atf aaiinp
qoio nxs^a eliriw tajKOd-i/a si^X XiJ-ru; gnx
id Io Bbnixld-owd- 10 'iXsi ;teixl ifi itda'u siost droc ytlii/b
.~t-:-
29
do not need it so early as grains. Orchards on the other
hand when well cultivated need little water in the early
summer, the greater part of their requirement occuring dur-
ing the latter part of summer and early autumn.
The following two Tables, taken from the report
of Don. H. Bark are typical of the irrigated sections of
Idaho. The crops and soils were divided into two classes
1911 ' 18 ' . ' . 325 ' . 52 * ' . ZO? . 945 ' . 750 ". 199 ' .' ' r. . 73
(1) Grain on medium clay and sandy loam,
(la) Alfalfa grain on medium clay and sandy
loam.
(2) Grain on porous sand and gravelly soil,
(2a) Alfalfa and clover on porous sand and
gravelly soil.
TABLE VII
Summary of Depths of Water Applied by Months to 122 Fields
of Grain on medium clay and sandy soils f/zj
Season
~T~
No. of 'April
plots '15-30
r~ ~ i
May 'June
i
i
~r~
JulyjAug.
i
t
Sep. 'Sep.
1-15 '15-30
i
1
'Total
'for
'season
'feet
feet 'feet
feet 'feet
feet 'feet
'feet
1910
39 ' .00
i
.320 '.645
T
.495 '.095
i
i
.00 '.00
1
i ~
'1.556
i
1911
49 ' .00
i
.021 '.717
i
.428 '.006
i
.00 '.00
1
'1.172
i
1912
34 ' .00
i
.000 '.914
i
.650 '.059
.00 '.00
1
'1.623
i
Average
: ' .00
i " t
.114 ' . 759
i
. 524 ' . 053
t
.00 '.00
1
'1.450
i
Percen-
tage of
Total
i lit
I i it
1 ' .00' "7.86 '.52.34 '
i
i
36.14 '3.06
1
1
.00 '.00
i
'100.00
adi no abiarionO .anlaig a ^Iies oa 11 b,99n Ion ob
9& nl -tecfaw sl^ll baa ba^viciluo llsw naiiw
lo cf'isq tenets I
lo anol^osa fisiaaiiii sri* lc Ijsolqipt sic ah*a .H .noQ lo
pw* -oinl bstivlb srcsw alloa ana aqoio ^11' .oriebl
,mQoJ -^fcrtaa bn ^B!O ns/ibam no alBiO (1)
bnc ^alo nu/lbom MO 'nisi^ ells'UA (si)
,1103 ^ilsv.313 bn.3 bGJBa eiro-ioq xio nis-iS
bna auo-'tcc no isvclo baa BlXallA
. i ioa
, J.3AT,
.T 1 .qaa' .q92' .guA 1 ^Itfl/ sitt/L'-S*^ 1 Xi f ; [
" ' r^F "^ r' - r r '
i i
1
1
- _^-^_ -- - T, -
jrf. V i_!^_ -'S ^-fej-iE "^ ; T^
oo. 'oo. 'eeo.'aeK'a^e.'oesJ oo. es
00. '00. ' 300.' 8S.' V..7 .'
'
' '.' . 6
n
J .
'
'00. ' -
! I ' '
i
it
I I
I I ' -.: !
30
TABLE VIII
Summary of Depths of Water Applied by Months to 46 Fields
&f Alfalfa on Medium Clay and Sandy Loam/fr?;
Sea-
son
No.
of
plxts
April
1-15
April
16-50
May
l .
June
July
Aug.
Sep.
1-15
Sep.
16-30
Total
1910
17
.055
,018
.531
.720
.002
.551
.004
r
.000
2.54
1911
18
.00
.025
. 525
.308
.945
.750
.199
.051
2.78
1912
11
.00
.000
.508
.445
.697
.474
.038
_
.000
2.10
Aver-
age
r
3 .t
.018
!
.014
.521
.490
.748
.592
.100
.010
2.50
Per-
.
1
cen-
tage
of
To-
tal
f~ ' '*
f
.72
:
.56
,
20.90
29.05
,
30.00
25.75
4.02
.40
100.
Irrigation water is usually applied during that
part of the year which corresponds in general with the
period of plant growth. The time to start irrigation is
largely dependent on the initial amount of moisture present
in the soil due either to winter rainfall or fall irriga-
tion, the available water supply and the crops to be grown.
Soils which have a good water retentive power and which have
been subjected to either fall irrigation or winter precipi-
OS
HIV
^gA
. -.
S8V.S
001.2
Oo.2
00.001
1
-i ""i
I "I
~r~
-,. '
_ ' 1,
A 1 -rr f ~ '
. T 1 , : , 1
1 r
,
L S.u
1
"l
|
1
1
,_. II..-,.*
l/^\
I3c . ' 200 .
CSV.' ise.
l~ i
BIO. 1 S30.
I
VI
oivr
i ..
11.
ria I 3AO
UG i o 4r -
80S. 1 S23.
320.' 00.
81
IIQI
!
i
;o .
&Y ! V8d.
S^ . ' 803 .
000.' 00.
II
2191
i
1
i
1
*I3VA
>i .
263 ' 8V (
r Q6. ! xsg.
MO. 1 SIO.
63J3
i
i
i
i
i
'
i
i
i
i
i
i
lo
i
i
-. -o'r
).
5V.S2 1 OC.X
30.6E' 09.02
z- r - QV
C?O . -i *
I3-T
t
i
1
el
nellqqB -^llB0afJ el -is^sw noi*?^fxl
jijr is-isnss nl sbno^si-xoo doldw "iss^ ed^ lo
d-xad-a o^ atnld- siff .d^wbig .tnelq lo
le *luttB l*lilai 9d^ no tfnebnsqeb vli
to Ilalrc-Ui tsctni* od- ^xedtls ewfc II
aqoio arl^ bn/; ^iqqtie I9v^w sldsllave 3i'ct_ r
svsrl ilolriw fcna lowoq 9vJ:d'n9d' r r r i : -s ovsti i.-
-Iqioeiq
o I bs:
51
tation, will generally be found to have sufficient initial
water in the soil to start plant growth. This is due to
the fact, as already shown, tiiat the water may be stored in
soils to a considerable depth as a film surrounding the
soil particles. At Utah, where most of the precipitation
comes in winter, it was found that in the spring most of the
water that fell during the preceding winter was held in the
upper eight feet (See Table VI). The quantity held in the
soil varied with the percentage of water in the soil in the
autumn. If the soil went into the winter in a dry condition,
practically all of the winter precipitation was found in the
spring in the upper eight feet. If, on the other hand, the
soil was well filled with water in the fall, a relatively
small quantity of the winter precipitation w as found in the
upper eight feet of soil. The upper couple of feet were, in
both instances, fully saturated, and the percentage dimin-
ished steadily with increasing depth. Hence it is clear
that when the soil was fairly completely saturated in the
iur r '-i-- ; :;c< c-iuy evepoi^.-te tc^.r-r. Iiave fcii<j
fall, the winter precipitation passed down beyond the eight
feet limit or the root depth. Prom 1902 to 1907 the per-
centage of winter precipitation found stored in the soils in
the spring--the soil going into the winter in a dry condition
--varied from sixty- three to ninety-eight percent. It is
wi fl *iB*a o* lioa 9 :tt n is
nif>^o^' 3 ntin a SB d*qeb elda-isbianoo B o^ alloa
lioa
o iaom ^oliqa srtt n ^aiflt on.'o'i asw *1 .leiniw ni ao:noo
* ni bled BBW i^nlw rjflJtbaow artf 'anlnuB liai *U
B fll folea ^i^xrp aid! .tJV eld-T 9 "
Iloa
a s^ cl
tb a nl ts^iw sdi o^al *naw iioa 3 rl: .
ni tool aawnoldc^lQioa-sq *nl ail* lo Ila
it ,6flad -xarfio aitt no .
evitEis-r s ,ifi i ai ' '' Jioa
- w
Ilsma
ni .aw isello alqoo la^qw oifl 1 .lioa lu Joal *rfsl
( - ao t b9*is-rtE Tfllwl .asonactanl
HOB
SCSI ^o^ ..ri*qab *ooi a*W 10 *l^
lo
.iiv--
32
evident therefore that in districts where the precipitation
comes in winter, early spring irrigation may have but lit-
ijRer - ! 11 blo" th'it vh-leh
tie value. On the other hand, where the winters are dry and
the summers wet, early spring irrigation should prove very
profitable.
Porous, coarse, sandy or gravelly soils, which
have but little retentive power, will require early irriga-
tion and for new crops may even require irrigation before
planting.
The effect that the rainfall, which falls during
plant growth, will have depends largely on the amount of
precipitation and the relative humidity of the district. It
has for instance been shown in Idaho, "that a light summer
rainfall has but very little influence on the IXity of water,
most of it being evaporated. Heavy rains of .5 of an inch
or more at a time seem to have beneficial effects, but the
Idaho atmosphere during summer is so dry and the soil is so
warm that lighter rains than this seem to do more harm than
good, for they not only evaporate before they have had time
to penetrate into the root zone, but effectually destroy
any soil mulch that may have been formed by cultivation."
The beginning of the irrigation season, may in
some cases, also be considerably affected by the temperature
iq axicfr s^eiiw atfoistfaJLb al tfsrict a-xclaiarld- ctaa>iv9
_4 vsm ridds^-Liii s^-toq 2 Y-t** 39 tistfniw ni asntoo
) sis Bi9d:ni?F slid- aigrlw t briB{ -isd^o arid- rtO .at/lev eld
fclcorle aoltfaglfi.t gnliqa Y-^^ 39 t* 91 * ai^rnmwa srfct
. Dieted- llptq-
iiw allo8 Y-t-t 9 ^' 3 * 1 ? ^o Y^ 11 - 32 *93iJ3oo tS^oioi
9''lil/pS1 iliW (TQ'flDQ OVl +113^91 SlC^li *Od SVBii
0i'V9 ijsm aqo r io wan io'i bne noid 1
ellsl riolrfw t llalrilai d-oaTls exH
lo jiOJOffiB 9ilJ no ^is^tol 35n.9q9r) sVBrl II iw ,f*v70'i3
sii) ail* lo v^ifjlmwri 9vioBlsi 9/Id 1 bnw n
-xlgil - 3 tsrW" .c/JcpI ni rr,'/o;la naod gonB^a^x 10!
1'lni slJail i r i6V. ;t0d SBX!
lo 3. lo snlai TjvsaH .bata'toqeva ^niad J lo cfaom
,8^05119 leioi'isnscf ev/3i{ od- ntsaa amlo :s *s s'torrt to
oa ai Xlou sj^ct one *^i6 oa si narwyja gnliub sisi
jiailct rtwaxl aiom ob od- msps sirfd- nsiid" aalBi isd-d^II tarid- .i
, anos -tool arfd" otnl sd'BTd'snoq cd 1
nJE Y fi!n -.
add; ila vi . i .00 dd CS!B . 2981-0 cioa
of the water. Cold water, if applied in large quantities,
will lower the temperature of the soil below that which is
best for plant growth. Hence if the soil has sufficient
water for plants to thrive on, it will be detrimental for
the <U?fcMbut,! JT
plant growth to apply irrigation water cf a temperature be-
low that of the optimum soil temperature.
id fit fcallqqfl 11 t i9^s?/ bloO .
wolstf Ilos sxid- lo txtffii9.q- r ra^ a
.j . -to'
d Cliw *1 no evhxrtt o*
;ae-i Ioe ntwmi^qo eel* lo ct^tid wol
34
CHAPTER IV
MOISTURE DISTRIBUTION IH THE SOIL
mea;;j)
It will be well, before discussing the question
of the distribution of the moisture throughout the soil,
to take up the question of moisture movement.
The moisture in the soil is subjected to various
forces of which the following are the most active.
(1) Gravity G.
(2) Capillarity C.
(5) Film Forces, such as
molecular attraction,
surface tension, etc...F.
In an air dried soil there is a condition of
equilibrium. The moisture contai ned has distributed itself
according to the forces acting on it, in this case being
primarily film forces. If the hygroscopicity of the soil
is satisfied, the moisture acting under capillarity and
film forces will distribute itself uniformly throughout
the mass. If now this state of equilibrium is disturbed,
as by the addition of water or by evaporation from the top
soil, the soil moisture will tend to redistribute itself to
the new conditions bringing about thereby a movement in
the soil moisture. iv.oisture will always move from the
wetter to the drier soil or from the thicker to the thinner
VI /IS
aar *r
arid 1 gnlaauoalb atolscf ^II?w 9d
\Iioa 9itf d-wodawo-tt** ai^eioni arid- lo nojt*i/dln;tell> 9&
.ctnQfr.evont sti/cteioiTE lo noiJaawp 3:Irf qw ajiad- ocr
awoii.sv oc^ bsctostcfwa ai Itoa 9/a nJ sii/ctaloa siff
J-aonx erict si-a :^i-.7ollci oai 39010!
........... .-tfsv^. ,
iqai) .
''i ;$)
loRt
lo rtci.Uiiuoo 3'ai- aiedJ- I toa bsJtib lis K/S nl
i bactwdlid-alfi ajarf -ban -tetnoo siwj-aloir, .
gnclea' 32^0 si--- ..-ti no yild-os aeofio'l ild 1 oct ^a
I to a W lo -cJioqooaot^. -I .aso^icl mill ^
bus ^1'iBlIlcflo -isbnjj yiictos s^urfal-cm .3lcitae al
j ^imtoliru/ 'ilaacM scfLrcJi^alD II iv as one
al fauJncflilupe lo ets.ia sixi* won II .aaflia srict
qocr 3:1* rno'il nold-s'xoqs-vo .' ^cf ic is-isw lo noid-lfs&B srict ^d aa
o* llee*! stfxfdiTKtelbet o* bngi Iiv/ snu^alqia Iloa sxl: J
ni ^nsmsvom B ^daiaiit *uods golsai^jd-^anoi^lbrtoo wan arid
arid- moil 9vom a^awls lilw e-u-- . 3i.udelo. lioe orii
iioa isi^b srii cct
35,
film the affinity between soil particle and moisture be-
ing so much greater in the latter case. And once contact
by this means has been established, it is surface tension
that drags or pulls the other particles along.
the lento
If the moisture content is somewhere near /capil-
lary point, the movement and the distribution will be
primarily due to P,G and C. When the maximum retaining
capacity of the soil has been reached any further addition
of moisture simply slides off the already present moisture
film, --neither capillarity nor film action having any hold
on the water, gravity alone acting.
The lateral movement of moisture is dependent
not so much on the result of capillarity, film action and
gravity, but to a greater extent on the first two only. The
result, as will naturally follow, is less than in the case
of downward movement. Gravity will rather tend to spread
the laterally moving water downward in a fan- like formation,
giving thus a uniform distribution only below the topmost
surface.
The upward movement of the moisture is entirely
identical to the downward movement, except that in this
case the action is a pains t gravity, whilst in the former
case it is aided by gravity. As the particles in the top
-ed a . '.onx bns sloWiaq HOB neswdsd -tflnttla ad* Mil
*3s*nco 90no bnA .sacs <i9**i5l erf* ai 1,8*39*13 do0m oe
nolaflg* doalioa ai *i <d3ild**39 n&dd Siiit au^sm aid*
anolfi aslold'i.'sq I8d*o 04* ailwq 10 agenl) *
;:G2 ..." ctuecfiicc st?/*aiont ad* II
ad lliw ^oi.t'^Jcfl^dei5 srl^ bne ^ns-Ttavom 9Jf t ctnioq
.-i jnuKJtXJMi srl* nedW .0 &ns 0,/9 ocT girb ^Ili
-iul ^rifl fo9Jlo--9i naacf sBxi I JOB eifct lo
aiOM ctnsastq ^se'xijs sd^ Tio aafilie ijlqat JE e^ujaioa: lo
ii noi-ioa nilJl ion &tialLtq*o lariJlen--. .mill
.^nicfOB enol3 ^ctivaig ts*aw 9d* no
cfnsbns'-jsfi ax 9 r in*slom lo Jxisir.svom Isisctal 9ifT
>ns nol*3fl mill t TC*liBlIlqoo lc lluaai sri* no rfowni oa .
ovtf *aill 9dJ no tfcelxs leJseia B ocf ^ 0cj
9330 an* ni nsrl* aasi al .woilol ^IlJB*w;*sn illw ae
ct 5ns* 1911*31 lllv? iptlvfiiO .*n9fn9vom b^awrrwof) lo
a. nl 6iJ8.wn-*o& -i3*Bw ^nivom ^Hai9*fll sri*
* r **
s ami*
9d* lo
*q93xs , "-^ o*. 1^:
j ' ' r\f\
qo*
36
surface dry out as by evaporation, there will be a gradual
readjustment of the moisture particles from the thicker to
the thinner films. But as evaporation is a continuous action,
so too will be the movement of the soil moisture from the
bottom towards the top, until the loss of moisture will be
felt throughout the entire soil mass.
The problem that the irrigation engineer faces,
is to be able to tell to what extent this moisture movement
will take place in various types of soil or what the dis-
tribution through the mass will be. It is essential for him
to know these matters, since whilst for one type of soil the
water applied will wet the mass throughout the root zone, on
another soil the larger portion may be lost by deep percola-
tion, the film action and capillarity being too small to
store the water. It is evident that the degree of success
which the individual irrigator attains is directly propor-
tional to his ability to grow satisfactory crops by using
reasonable quantities of water.
Irrigation water which passes below the root zone
of ordinary crops carries with it in solution valuable plant
foods, thus tending to ultimately render the soil infertile,
or, as often happens, if the downward leaching is checked by
an impervious strata, a water-logged condition results, fa-
^ as
slo.ti artf lo
airojjnltfnoo ^ si nold-B*ioqBve> se JxrtJ . sell.
ia Ixo3 wi* lo ^nsmavonv srl^ acf 11 iw oo^ oa
m lo saol eii? Ii*ra; ,qc; M sbie
Ki Jloa
aewtdvom yxi-.^sJtoKt eliJ ^rrsJxo ^aw o* ilai ot glda
.-afi an'* -td.'iw rcc iio^ 10 asqtf awoliBV nl ao^lq ails* Iliw
loi lal^neaaa el *I -ad illw aaam Siio il.
llos Ic aa^i SKO -io'i *BllrIw sorrla ,.ai9J*cir. 9aa/id-. woroi
srtt ctaw 111*
no
-alooisq qesfo
od- IIr;r.2 oo-t ^nlod ^ta'-J^-ta^ 80 ^i-a uoWoa ;rJ11 exit
aasooua lo aeigeb ari" *.^# tftwfilva el *I .is*w *d*
rfolrlw
-loqoiq \;
%d aqoi
.'ie-Js-,v lo asid"!
tfooi srid wof&d aaassq riolri* 'xad'aw aoljss^^ 1
eirfaxilBv noljftloa nJL *I. tfTJtir a^insaf eqoto Y^^-^O ^
Iloa aiit isbori ^Is?=my * Sftlfcna? eurij .abool
i a ifi?/ob sxl^ IT ,an3:,q-a a
37
v curing the rapid accumulation of alkali and hastening,
to a marked degree, the non- productiveness of the soil,
and thereby the failure of the irrigator. Consequently
the importance of gathering information concerning the
depth to which soils may be wetted by irrigation cannot be
overestimated.
The extent to which moisture will distribute it-
self after irrigation is dependent on the frictional resis-
tance which the water has to overcome. As soon as the
frictional resistance of the soil particles to the moisture
becomes greater than the forces bringing about the moisture
movement, the distribution will decrease rapidly and further
penetration into the soil stopped. The cause of the fric-
tional resistance becoming greater than the movement forces,
must be sought in the theory that the water is gradually
used up in the form of films in its downward mavement. The
finer the texture of the soil, the greater will be the ag-
gregate surface exposed by the soil particles and the great-
er therefore will b e the moisture distribution. If, there-
fore, a definite quantity of water is applied, it will be
used up to a much larger extent in the topmost layers by the
finer grained soils. A point will hence be reached where
there is no longer a sufficient supply of moisture to satis-
lo
aaanovld-oubc'iq-non arid- . seigab beiiiBia B o*
ettf lo anuila'l erf* YCfe r i* boa
nl ^ol'iarWas 1 eonarfioqml eri*
sd Jo/no noWslitl YO r 0j**o-ff &d ^aia ailoa do Id*
atire sis vo
Jilw
laaoiJoJ-tl eiW no
as nooa aA .anwo-isvo oJ z#d is*e -
saonol arid" na.x i^9'ts estnooad
.CIlw ncWxnJi^eib srict t *nainavom
a3iiv.o srfT qqcte Iloa arf^ otfr.l RClcTa
,aamel Jnsrr.&voir. .^itt r< 'tS isctsaia yilir.ooed ' aon^aiaai
XlI*J^>fii-= ai 10*8* sdcf c^iit vio*^ 9xid fl-t'^uca sd
eriT .In&rwv-on; IwuwnwoS all rtl amlil lo mTO
-38 9rfJ ad 'iJtw laJaaia sri^ Iioe srl^ 'io a;*xe*
-jB9'ig srfci- bna eeio^'iaq iica ed? ^d basoqxs 90fl.l*swe
-0OJ* .11 .nol^dxiieib a-x^alom eri* edlllw ^cl^-
. ec r iliw *i .beiiqqva ai iscfsw lo ^ ; i*jctswp s^l
eridr ^<J a^iavBl ^oomqo* .ari* :st *ne-lx& i3S*tai dou.r. a
-a 1*33 o-t 9iwJaJt0ffl--lo ^Iqqws ioelpniwe B issnoX oa si
38
fy the wants of film action, frictional resistance will
increase rapidly and the distribution of the moisture
diminish abruptly
Table IX shows the result of a laboratory exper-
iment on sandy loam. In a -glass jar some one and one-half
inches in diameter a celluloid lining was tightly placed.
The whole was filled with sandy loam, and sufficient water
was added to give an irrigation equivalent to one and one-
half inches of water in depth. The jar was then covered
with a paper to prevent evaporation. At the end of a week
the soil column was taken out of the cylinder and unrolled.
Samples were taken at the various depths indicated, oven
dried, and the amount of water present at each given depth,
calculated. Table IX shows the results obtained.
ili* Qonatfslas-'i ii;noiJoi'il <noWo;j mill lo edtffiw ectt
sift io noJt*i><JJfettfaJti> apd- bna
y to ^- tjj ' aeri 3il ^ swede XI
forK >no Oiito^ i^t asaiiyfl nl .;naol \fcxiaa xio
.baoelq ^1*118^ asw gninli ololwlloo a istfa;nBib nl
ie*fl.w ^nsioi'Il^a bfl o ,mecl u&rias rf^Jtv 1)91111 a.sa sloii 1 ?
-sno an^ aao oi ^naiavlups nci^e^/'nl ns svlg o* bsbc-s a**w
bsidvoo nerid- a BY; '. oill 1 ..laqai, ai oetfsw lo aarioci Had
>I56%' 3 'io baa srLt cfA .nclcffi'ioqava *ndvnq o^ aaqsq a rid
.&.[ I cam/ bn-2 -'fsbiil ) 'rf 'io iwo nsjis^ asv; nrrj/Ioo lioa arid
xisvo .bs-J-O-L-JuI aitfcjsij awoltuv ad* ^3 n
cavig not jaeiv, i&*^\v lo jciaoaxa arid bne t
jli/aa--: 3-?oia .XI sicfB 1 :?
39
TABLE IX
Depth from
surface in
inches
Percent water
present
Hyg. coef-
ficient
Net capillary
water
_ h
1
14.35
2.04
12.31
2
12.97
2.04
10.93
3
14.13
2.04
12.09
4
13.63
2.04
11.59
5 ^
15.03
2.04
14.99
6
13.22
2.04
11.18
7
11.88
2.04
9.84
8 ^
/
9.04
i
2.04
7.60
The results show a very uniform moisture dis-
tribution in the part of the curve AB, and the abrupt de-
cline of penetration after the point b has been passed.
Similar experiments conducted through a longer period show
that with an increase in time the moisture distribution
followed roughly in the way indicated, always converging
towards the point c.
These conditions are not necessarily met with in
field practice, the part be of the curve having been forced
down to a much greater depth by either the rainfall or ex-
: -Isoo .
-alib 9iwi
i
!
; tfoeeotq
15.
21 !
t
\.o O /
3T'J .
3-3. M
se.
01-
i
0.3
ve.2i
eo.
21
!>0 . 2
51. M
63.
11
J^C.
53. SI
ok.
1
.
SO. 31
81.
11 ;
*c .
t
22.51
MS.
e
:
be i
88.11
t
Oc>.
v '
1
K>.S ;
K>. '
^ i
rale
^ .-^clix
ijj ~<ri 3V - 13 .woiJa
3ilW89l'^
M
f>n.-i ,9A
3V100 a:Ii lo
diiq 9ii J
sio'il
. :aa
.p9aa-'c n^ocf a
bol-tsq ic^i-jo
cf drJoq
8
cij'sri^s.rraq' lo snllo
' -Ji.
cl noacf
JSrfT
tt - oo.". blsll
ia iloum a oct. nwofc
40
cessive irrigation. But it is abundantly clear that
the distribution when the soil is in an air dry condition
stops at a very marked depth, where the frictlonal resis-
tance becomes greater than the forces tending to distribute
the moisture. Greater attention should be paid to lighter
irrigations so that the total distribution abod may be kept
within the root zone, rather than forcing it beyond that
depth by excessive applications of irrigation water-
The frictional resistance will be a large ex-
tent be dependent upon the initial amount of water present.
The greater this amount, the smaller will be the frictional
resistance and the greater will be the downward penetration,
and the abrupt change in moisture distribution. It is a
matter of common experience, the farmer finding that the
water does not penetrate the soil deeply during the first
year of irrigation; but, as time goes on, the soil becomes
wetter to greater depths, and at the same time less water
is required by his crops.
The moisture content of the native undisturbed
soil in arid regions is usually below the point of lento
capillarity. The first water added is used to bring the
moisture content up to this point, and as this is accom-
plished, water moves downward freely; the plants being en-
abled to secure their water supply with a corresponding
d-axfcf isslo ^Xcfiusbiurda al d-x *S .noldflgxTix sviaaso
n. ' ; iis ns ni al Ixoa said 1 naifw ncld-wo'lndexi)
oJ gnibnsd' asoiol s.ril ncrW iscta^ asmoosd
feisq scf bluoiia noii'nad-^a. na^asiO .aiwd-alom srfj
> "
qasi ed ^sr.T f50;Jr nol^udiiJtalJb Iccto* ari* ctsrlcf oa
' -dl ^nicyicl nsrid" isr.utei t enos d~oo
.19*3W noits^irti 'io anoijjeoliqqa sviaasoxs ^d- rfcfqeo
-x-3 e^tsl &=..(.-t3v: Lily son 3^.3 ia.3'i Isnoi^olil sriT
lo 3-rtuoffw Xeirfinl arid- noqu dxittJbflsqsfo-iacf
eo r Xiiw nsllwiia edt ^nwo.TCS elrf^
biejm/oi; sri^ scf iiiw is^fiotg erf.! bna
licfaib .9^ r.'^ a lorn nl o^riBrfo iqmdB 9fi;t
13)7^31 s-rlct .eoriaiiaoxs nommoo lo
. Iqasb lloa srf^ sie'id'snaq ^on asob
aemooscf Ijoa s^tt ,no eeos smx* aa . d-wd joolctflgxTiJ: lo
aasl emid- ssise sa'd da |jEj t aildqe5 TS^BSIS ^ i
.eqoio aid
wd-eifonw svlcfsn arid 1 lo drisdnoo r sriT
% NVsx
ic .tnioq slid woled \LLstU3 iJ &iiB ni lloa
nlrtd d bsau ai fcsbbs riT .\^lrrslllqflo
oo com
-ns anls adrtsq s .:i isaw
:aa
41
smaller expenditure of energy. At the Experimental Farm
at Davis the results obtained are given in Table X.
TABLE X
Depth
T~ T
1 .5' 1.5
i i
2.5
3.5
4.5 1 5.5
i j
Dry at
i t
i
Percent
vie: i
,
Moisture on
1 !
i
ovendried
t 1
O | tl
basis
| i
1
1 . ^| i
( i
Boring I
'21.05 '18.16
15.33
17.04
20.48*14.29
6 ft.
t
i
Boring II
'20. 49 ! 20.39
19.06
19.04
23.19 '14.74
5.9 ft.
t i
i
Boring III
'20. 55 '17. 92 '16.04
i i i
18.19 '13.26 '12.55
i i
6.4 ft.
fl*n9Jtidxa sitt *A .Tranone 16
.X alcteT ai rtavlg e-xa fcanlacKfo
X
is I lama
riJ 1 a
P- , ; .-
* "T t
i . . . - . -y " ' ' ' . "-
Id '5.3 '3.*> '
3.5 'B..S '
1 1
3.1 '3. ' r^qsa
i i .....
t
1 1
i t
! t
1
1 ' cms 01 si
1
' * no yxud'aloM
1 * C~ t- ' "~ * ^
t
i ;
i * alaaa'
i i
!
! . 1
' 6S.M 1 8.Q
1
: 4-O.VI' S5.3I
i .
31. 31 ! 50'. 12" I giioa
1 frO.QI 1 80.61
es.os 1 Gi>.o2 ! ii saiioa
^ 1 1 ~~
t !
I ;
Oi -> -i o > ' ao s* r
OO . i>-U Oi. .<JJL
i i
1 !
; 29. VI 1 3-3. OS 1 III sniioS
i i '
41a
These results were obtained under typical field practice
conditions, the samples being taken in an orchard.
sn imiretti.ec! dx;ty of th* svsiiat.v y.
The results closely follow those obtained in the
laboratory. Is there then for every soil a definite quan-
tity of water which will distributees moisture uniformly
throughout the soil mass to just a sufficient degree and
depth to prevent any deep percolation loss and be of maxi-
mum use to the plant? It is still too early in these in-
v various soils-* JbErrvs'. < :n- cl tns r^si* : te
vestigations, which are being carried on at present, to ar-
rive at any definite conclusions. One fact is however ap-
parent, that whilst we may increase the duty of water very
considerably from purely scientific considerations, it is
more the mechanical application of the water in field prac-
tice which retards the obtaining of any such increased ef-
ficiency of the water. The tremendous waste, due to the
improper levelling of the land, the loss at the head of the
border or check, the waste at the end of that border or
check, the skill of the irrigator and so many other mechan-
ical factors are the more responsible elements for the low
duty realized. Even if it were possible to apply water
in such quantities as would be befct from the preceding con-
siderations, it will always be the mechanical factors to
90 ' - - cfc
na .J&2J8
98orfd- woiiol ^isaolo aiiirasi
-rump gjtattob a Iloa -fi
e-wtfaxoai alt e^-dlid-aifi IIlw iloiiiw i9*.ew ic
JnaloJtni;a 5 *awt orf'aaaai
o 9d bru aaol nci^i-loo^^q qssb
oo J llita si
-qj 13V97/O.H ai ctoBl anO .acoieul-onco **lnil9& Tflcifl
2" dt . anolljsisblanoo oJtlid-nsxoa ~^i9iwq moil
-p3iq Mail nx isdrsw arid lo noldspiiqqa laolrMffoe. w 9'io
r r * -4-
-lo baaas-'iorii iioi ^nc lc ^iiniad-do and aDiadoi noxr. QOXJ
t __ 1*V
arid lo bagj sxfd- dB o,cl sdJ- .finai 9rld lo aftlilaval igqoiqwl
ic i9biod dsdd lo bns arid 1 d;*' adaaw eifcf ioedp 10 i9b-i'
:3Bt o^ bn;a lolu^i'til sdd Ic XiJbls ado t ii03iiO
)JO;3l i^JOl
r,4 aa e.onp
r ioi ajnameig 9iai-
I9*w \lqqa od- slcJiaaoq 9i9w 41*- 41
-nco 3ilc909ic sdd 2101! *9d 8 SB aoictldrisup dp^a ni
^j- n-to<*^ r'anir . ..iis.il i'.T dl ^
42
which prime attention will have to be given for obtain-
ing an increased duty of the available water supply.
The California Branch of Irrigation Investiga-
tions of the United States Department of Agriculture has,
in co-operation with the State Engineering Department and
the Agricultural Experimental Station at Davis, studied
during the past three years the distribution of irrigation
v/ater in various soils. Observations of the results,
which may be regarded as those of typical irrigated soils,
will be presented. The observations were made under two
somewhat distinct conditions. First, .studies were made
upon various farms in the Sacramento River Valley, on
fields producing alfalfa (lucerne). Soil types represen-
tative (according to the Bureau of Soils U. S. D. A.) of
extensive areas in the valley, were chosen. The other
conditions are those at the University Farm at Davis, where
alfalfa was grown upon one-fourth acre square lots. The
surface two feet of soil is a loam of remarkable uniformity,
and the third to eighth foot sections consist of a sandy
loam of recent origin, pocketed at irregular intervals with
coarse sand or clay loam. This fine sandy loam lies upon
an undulating clay which extends from nine feet to a depth
of twenty or more feet below the surface.
avail Hi* noiJ-nsioB a^iJtoq tfoidw
n" o
lo
*.-.._ -<!-'" f
as^sicl bftctlnJ sil^ lo a
c srfd- rlJiw noWiJiaqo-co ax
t alvsa *s
9T; srl* lo anoWsv^aacTC .aiioa awol-i v rtl i3*.
sIJtoa bsrfc^liil Isolq-?* lo asocfd- as fesiji^adi .sd ^m rfoldw
acf Iliw
no <Y 3 - t - BV 'ts'vi/i c*n?r.ia-ioj3C srU nl annal awol-iav noqw
asq-^f lio; .Om^o.c/I; sliollB griiot/boiq
lo (.A .G. .o' .u alloS lo ;j33 r j;jtl axi^ od 1 j^nibioooti)
enT .nsaorio 3-isw ,^3! Lav siicf ni 33313 svi
tol 9-^fiypa 9ioa ii^-iMol-.eno noqu nvfois aa\7 all.aiis
alcfs^ismai lo KISO! G al lloa lo tea*! owl aoBl-ius
>tcol ddjiis od 1 b'l.t-.J srid" bna
JHOCU as II fOBo! Tjbuae suil airfp . ^slc -ie nBa eetBoo
(
a -':rfw ^ ! lo aaWsiwbnw.afl
39l S^Ofll 10 VdTIdWd' 10
43
Sacramento Valley Experiments
Silt Loam Soils. In Table Xi and Figure V are
presented results of moisture determinations upon three
tracts, classed as silt loam soils, which are based upon
one hundred thirty-eight six feet and thirty- six nine
feet borings. The curves of the silt loam soils converge
gradually from the surface of the soil downward. This
may be due to a large extent to the fact that these soils
do not dry out as rapidly at great depths as to the more
porous sandy loam 'soils. The average amount of water held
after irrigation was 5.20 inches per foot, or enough to
fill fifty- one percent of the pore space.
_g_l
30- ' * QCt ^ '
.7 . ai ' le 5 io t --
en xJe-Yd'Tci^* bns ctasl xla *ri8l9--*Tld* fcsibn;
3: . elios HtBol ctlla sdrf- 10 SSVIJLTO sdT .asni^ocf :
IT .Mswnwob lioa eri^ Io 9Blwa xf;t fflo-':
- ^rW- -tool s-ffcf oJ- ^nsct-xa osl B od-.e-
as s
j^rri;oma saflisva erfS .alloe* MBO!
io <ct-ool 'isq ssifonl OS.S BBW i '
s r ioq sriJ lo ctnc-
. ,
. ;. . .
44
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01
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y
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45
In the case of the Bundy tract, four irrigations
were given of 17.22, 12.20, 11.55 and 7.77 acre inches per
acre respectively. The moisture determinations indicating
that the following amounts were retained in the upper six
Irrigation in Acre
inches per acre
Percent acre inches
per acre retained
on top 6 feet
Percent re-
tained
Percent
lost
17.22
:; 4.01 i
; 23
77
12.20
3.27
27 * ;j
73
11.55
4.05
35
65
7.77
4.73
61
39
The Table shows that in this case for a total depth of nine
feet only 5.13 acre inches per acre was retained or 44.4
percent of the total, 55.6 percent being lost beyond the
root zone. In the Hofhenke tract, the following additional
results were obtained./^
ch -
ol 1
VV.V >n3 oo. Cl .02.21 .22. VI 'io nsvig stevr
9iJ.rcta.tom erfT
S2
16
' asrJoni
ctoel
10.
V2 . ?,
S0.fr
3V . -
lo rWqsi) la-cfod- IG!
.> to bonie^oi UBW 3ios 'ieq
Isno
lwollol
<o octet
srtf
-i 1 9 r ioA ni no Id 1 ag it'll
no
1 as. vi
' 0'2 . SI
!
32.11
i
I rcr* v
os 51. 5 ^Lao
sdJ lo ^aoiaq
oH aticf nl .srtos ;toc
i T
46
Acre
per
tion
inches applied
acre per irriga-
r~
Acre inches per
acre retained in
the upper 6 feet
"
Percent re-
tained
r~
Percent
lost
18.76
5.42
29
71
15.74
5.78
24
I
76
18.86
5.36
28
72
13.22
3.50
26
74
The results show the obvious fact that the quanta
ties applied were much too great, the losses by deep perco-
lation being in all cases excessive.
-5 ' <VT *
.gs^l ^g
q aoiioni 6 r ioA fcoxi ;
ill
9rj S10~-' -B'3. t l''lJt '"19q 9"
'*ss
1 S ID ecu; 9ii^'
I
r
i
- I" "
'
92
i
l
S*.2
ev f 2
l
!
8V. 5 ' *V.3I
i
SV * 82
1
as. 3 ' es.ei
1
1
Y ' SS
1
03.5 | 22. SI
i
1
.
-
-** -"
sil* *dd* ^ojsl a'jjolvclo srW woila 3^10331
-ooiaq qs.aD ^d 2 9 aaol snct ^ss'ig ood io;.m: aisw bellqqs asW
.9V.cieeo;:9 asaso 11^ ni salad nol;fe-X
47
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c+ H) H-
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4 CD O
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4 ct
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-fr-tf-
48
Clay Loam Soils
In Table XII and Figure VI are given the quantities
of water held before and after irrigation on a number of
farms having typical clay loam soils as determined by two
hundred ninety-six six feet borings. The Figure represents
the average results. The increase in moisture varies from
1.35 in the surface to .28 in the sixth foot, as compared to
a variation of 1.15 to .44 in the silt loam soils. The in-
crease in convergence of curves with depth as the texture of
the soil increases in fineness is apparent. The water con-
tent decreases appreciably after irrigation with the depth
of the soil. It is therefore doubtful if the maximum capil-
lary capacities of these soils were satisfied. The average
amount of water held by the clay loams after irrigation was
3.49 inches per foot or enough to fill fifty-eight percent
of the pore space as compared to fifty- one percent in the
case of the silt loam.
The following additional results are given to
this type of soils. f/8)
v' iix -.!>> cct E . c xiojS*
a.-DViuo 'io soriD3 < -i5vnci2 lii a;
^ssrt^nil ni asas&ioxti lio'i
a-flp f-f Hi? *) >T CJG 15 cJ'^ci ' -^
v w i,^-J . W v? X ^1*3 *^
0*10 Is'i sa d" a.i >tl _.Iica 9J
silos osaf.*^ lo .g-@l^l5>aq*jo
Io sndS vcf jbl?ri T
j-ne 91 &q sno --r j'l i"
49
Farm 'I
's
;s
rrigation in
.ere inches
er acre
Acre inches per
acre retained
in top 6 feet
Percent
retained
Percent Lost
O'Hair
6.24
pr ^"i
5.58 ,,
j
r , 57. *
45
I T 5.18
2.11
66.
54
.: mount
5.24
2.14
66.
54
Guile
7.28
4.05
<c 55.
45
5.94
5.41
91.
\
9
Geer
24.00
t 5.59
25.
77
,. 18.19
c 5.28
18.
82
12.15
5.57
-+ 44.
56
p a |-
24.54
h
5.76
15.
85
A striking condition was obtained in the case
of the O'Hair field in that, while the percentage of the
irrigation water applied retained in the soil decreased
with the depth, the amount of moisture in the soil before
irrigations actually increased with the depth, apparently
due to the capillary use of ground water, which stood seven
to nine feet below the surface.
In the case of the Guile field, very little water
penetrated below the sixth foot. At the time of the first
cutting the moisture content of the soii was so low, that
1
28 .81
as - M
28 .51
Xe'a 13q
cfc^f r i j*"
^_/ X V. 7 * I * Li
1 rrc.tt
r Q t' jDSfii&d'S
0- at '
^ W*?
a&r : onl ' 31
; *ert c-
qod ni 1
31 OB I
* -1
35.,
5 '
^2.8
:
I
.
11.
S
81.6
'
1.
2 ;
& -
!
i
so.
&
82. V
t
i
1
r^
_,
te.a
1
!
ee.
c
00 . ->S
1
i
8S.
T,
91.81
,
i
|
!
1 ^ ^
2 '
P r c 1 r
Go. . AJL
1
1
i
1
ev.
o
i-5 . i?2
1
1
1
-, pfpi *> *D rr
F- ^T.^R &
- fTie'-I
. 59
g .16
VV ' -
' '
ner lo e-.^sctrisoisq Qtid- 31 It;,; ^sr-d- nl Mall .iiaH'0 silt lo
lies 9;i:i ' . -:ct9i bsllqqs.
floe sri-1 n- 9'-j:;?3. f oni lo juwoftus srl
qqs ^rf^qsfc erfd rld-i^r fceae$*onl ^llAStos anoictB^l'iii
nevsa 600*3 dalrlw ^s^sw bm/ois lo saw ^Bll|q0& erl-l c;
iwe 9i* wolftd cfssl snin oit
srl- 'io sml* 9x5^ *A .*ocl rf&xie 94* olsd
,wol oa asw Iloa orid- lo : . o siuctaiom add"
50
nowhere In the upper six feet was it much, if any, above
c ; :^ :" >
the wilting point. The same conditions were approximated
at subsequent irrigations. This no doubt accounts for
the large percentage retained, showing again the influence
of the initial amount of water present. The smaller the
amount of initial moisture present the greater will be the
amount retained and kept uniformly distributed. On the
other hand the greater the amount of initial moisture pres-
ent the greater will be the downward penetration of any
subsequent additions of water.
Another very striking result from the above
Table is the large amount lost beyond the root zone (assumed
to be six feet deep) in the case of the Geer tract. This is
unquestionably due to the large amount of water used, which
should not be mistaken for a large head of water. It is but
logical, that once sufficient water has been applied to
satisfy the capillary capacity of the soils, any further ad-
dition of water will increase that amount which penetrates
past the sixth foot in depth, decreasing thereby the percen-
tage retained.
9-iaw afloWJ-anoo er.B3 aril- .Jnloq snl*IJw artt
on siriT .enold-ajjl-nl
l wfcf nifiSfl 3fJt ^rla
' . a I^WiriJ 9 d.
eitt tellflAB 3^ .*nea9'iq to^aw ic invar. a I^
i
r, Isl
ild- riO nncm; tns >9ni^9'i
aaiq 9iu*aioni Jajtdiai lo cfm/anw sucf -
lo noWeiJsfiaq Biewnwob orW ed II-U ifslc
.-r,^j3w lo anoi-Ubbs
bsnuass) onou Jcoi eiict bno^u .Isol Jnwomo 9^-1 sr al si
ei a i^ .*o*rt islo wl* -o S3^o oiict nl <q&ab *oal xa
rieldSr" ,fc9a ie*aw lo imro.iur 9?,-*? I 9itt o* ewb ^I^n
*ud ul *1 .i9*'fi* lo bssii 931^ B -icl nsAi^alK sd *oa
07 bsllcofl need 3-ri 'i^ctsw iasioilltja 90no d-siid ,I*olaoI
-ha isxaiJJl -^ ,21103 3^ lo ^loaqBO ^.^IlxqBO aricr vlal^a
ll* ie*w lo noJ
nl *ocl HJxla 9i ^ : aaq
c
51
s
I?
H>tt?
O tJ
H 1 CO
H* 4
M > W CD
M > tO ct
CD *Ci
3 P
P H) CD 4
P H> CD ct
P H) CO P,
CO ct
CD
O ct l*b P
O ct H) M
ct Hb<<J
P
Ct
*i CD o OP
*"i CD O CD
*-j CD O <
^
O *
CD ^ ^ CD
CD 4 ^
CD *"i *^
CD P
H)
P CD W
P CD S
P CD SS
*"i ct
B H
KM H-
ID M H-
CO
to o
CD ^ M
CD 4 H M
CD 4 H t-'
P O
H-4
4 =* t-
4 ^ t-
H-4
P"H^
O ct
(W H-
0^1 H* ^
te^ Q
fo OQ
P OQ CO
p OQ CO
CD p*
H-
ct P
ct P
ct p
P
H- ct
Hrt
H- ct
CO
(jt)
O H-
H-
O h*
P
P
^ P
P
H
P
P
1
P.
~- * - ' .
CO SZ
p O
iN >>
M M
to to
Hi
*5
W W
CO CO
ct
I- 1 O
CD H>
to
(-> W M
\-> W M
MWM
K
-3O W
Ol O ^
<JO W
Ol
o
H-
M Ol Ol
co co o
W W O
CO
CD ^
ro to
to to
to M
M
4 CD
w tf* o
01 <JO
M H CO
Ol
>
-3 M >
M O CD
w ro co
CD ct
to to
to to
ro to
CD
(O
^J B
to 01 w
o oo oo
to 01 w
CO Ol O">
H Ol W
tO M CO
Ol
ct
o
ro to
to to
to ro
w
1. 1 r
o
* *
1
Hi tt>
OCO -3
<l O W
M CO Ol
O -3 00
w CD ro
Ol
o
O/T\
IP
H*
w w
w w
W w
jfi
*
1
u)
O H^- >
M to if-
I- 1 Ol -3
Jl
O
to to rfi.
W CO Ol
-3 rfi. H
w w
H -3 CO
w w
O Ol rf 5 *
WOW
Ol
Ol
W CD tO
(> ro oo
O Ol Ol
^ J
o
(-3
H M
1 j i ^f
M H
1
O
tO CD Ol
ro CD 01
i- 1 oo 01
01
ct
*
P
too co
CO O H
rf^ O Ol
Hi
O Ol Ol
W Ol W
CDOi-CJ
rh
1 1
en
o
M
K
M
1
1
,H
H
*?
5
W4 f j r,* f , "'". V -
' t
I <n / < > r" f < i
. VR S) * M ,
M ! 4 - :H < *< MOJ
5^ 3 f. M*P 't ^
S'-gjE -gi;^ 1 ^
5 , co PO '-' f ^
j " f:? +-J
t}| ^ ;_i -f> --i -t-. H
23 Q ."HO . 'H
. .. - - -
: 33
M
tfH >
CO
r
| ^. oi 01 '-'-' ^ ^
*
_ ! '
o
H "1
-< -*!
O
rr - r - -
,_i L H M TO M M '-^3 H
. ...
ro! W r - - r ''' c>
o -o ^> o QJ QJ n, 1 ; ro M
.__ -- ------ 1
03
p
M
M tg
B tf
o <
r ~ ~ r t
c., ^^ . & . >c/ ! .
ro' 0> - o !>> 9^*t
GJ <yj ro S3 O M ^i -
L _ - - -
^
'~> ff)
-rt L o
O
O3 03 Cfl CX5 M c>1
4. g^ ;^SS ^SS i
t '"*
ioi c'. c/ c/i ci w
ro! l> <o CO M p^ ^0 p
Crt O> fO -4l M C-- . ^ O C- i
i""~l *~f
i
(OW
^ . . ... .
, u-} ''(
ro o> 5'.') 4i '
1
. . . . .
rol fO O fO 4i rO O
O ' 4i
(
| C'
r
^ M ~ MM ' M
fO rO CD CA
. "* *
M . -; C'i
fO rt) O
52
Clay Soils
In clay soils the maximum water holding capacity
is sometimes limited by the pore space. This condition
seems to apply to the soils described below, the volume
weights of which were found to be very high. The total ex-
ternal surface area of these soils is in all probability
very high, to judge from their mechanical analysis, which
showed 24.54 percent of total sand, 40 percent silt and
34.84 percent clay. Yet the quantities of water found in
them both before and after irrigation were extremely low .
The observations made upon Clay soils are present-
ed in Table XIII and Figure VII. Figure VII is based upon
86 six feet borings and Figure VII contains the averages of
568 borings. The Table reveals at a glance the striking
fact that the surface foot of soil was appreciably moistened
by the irrigation water. It is doubtful if the capillary
capacity of the wetter section was entirely satisfied; yet
it held after irrigation 5.06 inches of water or enough to
fill 64.3 percent .of its pore space. The sixth foot, which
was kept moist by the ground water table, contained no gravi-
ty water, but eight-six percent of its pore space was occupied
by capillary water, leaving only sixteen percent of pore space.
The Purdy field was irrigated four times in the
;od 19 Jew ffurniixafs arfct alloe ^elo r*I
no' ) aldl 1 .aoeqs 9toq ail* ijd be^lmx! aairtidsisoa al
- t wcl9d bsclioaeb a^ioe sdct- od" ^Iqq^ o: amsse
-X9 Isd-o* erff .rfBirf ^sv scf oi bnu-ol siaw rloldw Ic adrl law
v^llJtdedcnq Ila ni ax ^lioa asorl* 'io. BD-IS soBl'iwa iBina*
rlolxlw .aia^IaniJ Itoinjeriag.'a -lisrit moil 33^^C o* *^3^ T? 9V
bns .d-'JCia *asoieq 'O* 1 ^- r i a s i^cto.i lo dnso-ioq ^6.^2 bsworla
ixi bsutdft. is^-3-.v 'iu aat'rid-aaAr iel .^lo drteoisq ^S.I'S
i
. wl ^Is.'nsi^xs eiew aoiJ.gr-l-iii nsrfla brts eaclad iWocf ntsrl^
J-iisss-iq s s i3 alloa ^fliO noqw 9bm axiolcfsvisBd'o odT
noqi; boesd ai 1IV 9iJj;9i r i .ilV strjgi^ fon^ IIIX sIcfsT nl >e
3iW BKlsd-nso .iw^W 6na s^nliocf *S3l xie S8
arid- gonsl3 s ^.s. ais-svai elcfB'i 1 sxfD .33x11^10.^.8!
HOB Ic ctcol oojaltae
of> ai ' ^*aw no
aaw rroWoaa ie**9W- siid" lo
ol rfguons f io isie^ lo ssxfonl DO. 5 ooWssiTil T9*l-s
rlolrfw ,^co1 ri^xla arffi . aoccs yioq a^ lo, fcrtsoisq <S.^<3 lili
-Ivaig on b-enisctaoo t io'J3^ tsd'aw _i?nwc- . . Y<^ J'siom ^qdi asw
belqwooc a.sw eosqa sioq act! lo ^nsoiaq xia-^rf^ie ^xrrf .tecfaw ij*
rfrk-^nt*! 1 tTT''* f VG
.908O3 9ioq zo jn . -->- i?osw ^li-ixx^-j \,i>
nl adnrW " ^^ Yfcii^ 3iiT
55
season. Of the 7.08 inches In depth applied in the first
irrigation about twelve percent entered and was retained
in the upper three feet of soil, of which about eleven per-
cent was in the upper foot. In other words, practically no
moisture penetrated below twelve inches. "In the second ir-
rigation a depth oi 4.55.inches was applied, nearly all of
which penetrated the soil and of which about forty-five
percent remained in the upper foot. In the third irrigation
a depth of 4.80 inches was applied, of which approximately
one-third remained in the upper foot, with no increase below
the second foot. The moisture determinations before and af-
ter the fourth and last irrigation, when a depth of 5. 84 inches
was applied, indicated that the soil became more impervious
to water as the season advanced, for about sixty-six percent
of the amount applied was retained in the first foot, with
no significant increase below that.
The soil of the Tattle field is similar to that
of the Purdy field, but slightly coarser in texture and a
little more open and permeable. Moisture determinations were
made from ten borings before and after irrigation
the second irrigation and nine before and after the third
irrigation, a depth of 4.08 inches being applied in the first
case and 4.16 inches in the second and third irrigation. At
bs Jtlqqfi.rttqob.nl agrfoni 80.7 artf $Q
bn^ beiaottS d-neoieq ovlewct twocfs , iiil
cte rloiiiw lo *Iloa lo cfesl se^itt isqqu srf* nl
. ab-xow isii^o I .^ocl loqqjJ sxl* ni saw
we lac?
1 bnco33 9 -e .as
lo ila ^Iiasn. .bailqcB BBIT asiionJ-.Se'.^
l ^0co r fi riolrlw Ic bar. Iloa sri* ps^Bi^snsq ifolrlw
* -rf* ni .?oo_1 leqqw edo nl fcsniBnisi ctnso'iaq
rlelrfw lo ,nail^qa SBW aailonx 08.^ lo diqab B
on
-la Bas.-sioletf anoi^onlnweiab etu^aloni aif! .rfool bnoosa
ssrtonl^S.S lo d*qeb
smaoa-. srW cfcrid- bs*aolbI ,69ilqqa BBW"
xi8-\>txis j;;ccfs 'rol .beortavbu aoaiaa srtt 33 IB^BW ocf
dctlw ,-iocl *eill srf^ ni b9nia*oi aaw bs^lqqB drtuorfts add
.jisnJ- vYoied aase-ioni d-naolllnsia on
od- i-Ilwia ai bie'll si^ctisff srl* lo Iloa srff
bno
eitrtalpIL .eldaeiffisq bna sqo
isd'lB buB siolsd STUiliocf us? moil e
. 1m 1 ; ' 9-f-
srf- ' rf^qab a t n ' liil
ol^je^lii: J i asrionl 31.* bnc seao
54
the second Irrigation ninety-three percent of the water
applied was found to enter the first three feet of soil,
about one-half being retained in the first foot. In the
third irrigation forty-four percent was retained in the
first six feet, three-fourths of which remained in the
first foot.
lo d r n'dori:
.cfoo
SBW
rioj:
.<t<
-f o
": asrfonl o--S
-
TABLE XIV
Irrigation
Treatment
T 1
'Time of 'No. of
'Sampling 'samples
Moisture content in acre
Depth at which sam-
ples were taken
feet
.5
i
i
1.5 ' 2.5
i i
i i
3.5 ' 4.5 ' 5.5
2 6 inches
'Before Ir*-
i
t
t i
i i
'Mgation '
14 i
1.78
2.03' 2.14
2.46 ' 2.37 '2.13
Plot B
'After Ir- 1
t
i i
'rigation '
14
3.26
2.99 ' 2.86
2.69 ' 2.75 '2.19
'Increase '
1.48
.96' .72
. 25 i . 56 ' .06
i i
i
i
3 6 inches
'Before^ 1
i
i
'rigation '
21
1.68
1.93' 1.91
1.80' 1.43 '1.29
II
Plot C
'After Ir- 1
t
*
'rigation '
21
3.54
2.99 ' 2.82
2.45 ' 2.10 '1.86
'Increase '
1.66
1.06' .91
.65' .67 ' .57
i i
i
i t
4 6 inches
'Beforeli* 1
i
i i
'rigation '
28
1.76
2 . 06 ' 2 . 06
1.87 ' 1.59 '1.49
Plot D
'After Ir- 1
t
i i
'rigation '
28
3.30
3.06 ' 2.75
2.26 ' 2.02 '1.87
'increase '
1.54
1.00' .69
.39 ' .43 ' .38
i t
i
i i
4-7-5inches
'Before IP-'
i
i i
'rigation '
28
1.95
2 . 16 ' 2 . 08
1.85 1 1.73 '1.63
Plot E
'After Ir-i
i
i i
'rigation '
28
3.20
3.16 ' 2.95
2.60 ' 2.40 '2.19
'Increase '
1.25
1 . 00 ' .87
.75" .67' .56
i i
i
t t
4- -9 inches
'Before :&>'
i
.' V
'rigation '
28
1.85
2.04' 1.92
1.76 ' 1.87 '1.59
Plot P
'After Ir- 1
t
i t
'rigation '
28
3.17
3.10 ' 2.82
2.52 ' 2.57 '2.34
'Increase '
1.52
1.06' .90
.76 ' .70' .75
t t
i
i i
4-12 inches
'Before Ir-'
i
i i
'rigation '
28
1.91
2.18' 2.05
1.96 ' 2.11 '2.32
Plot G
'After Ir-
i
i i
'rigation '
28
3.24
3.30' 3.04
2.99' 3.25 '3.41
'Increase '
1.33
1.12' .99
1.03 ' 1.12 '1.09
i i
i
i i
Averages
'Before Ir 1
t
t t
'rigation '
147
1.82
2 . 07 ' 2 . 02
1.95' 1.85 '1.74
'After Ir-'
i
i i
'rigation '
147
3.25
3.10' 2.87
2.58' 2.51 '2.31
'Increase '
1.43
1 . 03 ' .85
.63 ' .66 ' .57
i t
t i it
r
56
55
Lnches per acre Foot of Soil
Total Wa-
ter at
Depth of
Total percent-
age of water
retained
i i
i
i
6.5 ' 7.5 ' 8.5
9.5
10.5
11.5
0-6ft '0-12it
i t
t i
I !
;
i
12.91'
i
1 1
1 !
t 1
,
16.72 '
3.81'
31.7 !
1 1
.
i
< i
t t
r f
10.04'
i
I
i i
'. t
,
15.56 t
5.52|
30.7 ?
I 5
i
f
! 1
t 1
' :
10.83'
i
-
1 1
1 t
1 !
4
15.26 '
4.43'
i
18.4
1 t
i
1.47' 2.81' 3.24
i
3.63
4.25
.
5.10
11.40 '31.93
i
t
2.21' 3.64' 4.18
.74' .83' .94
i i
4.22
.59
t
4.52
.27
4.66
.44
16.50 '39.93
5. 10* 8.00
i
26.7
i t
-
i
i
2.56 ' 3.38' 2.84
4.04
4.53
4.69
11.03*33.07
i
I
3.33' 4.08* 3.98
.77* .70* 1.14
t t
4.49
.45
5.08
.55
5.15
.46
16.52 '42.63
5.49' 9.56
i
26.6 '-
i i
:
t
3.37 ' 3.16 ' 2.94
i i
3.88
3.86
4.46
12.53*34.20
i
1
4.22 ' 3.77 ' 3.76
.85' .61' .82
i t
4.32
.44
4.32
.46
4.92
.46
19. 21 '44. 52
6.68 '10.32
i
21.5 *
i 1
2.47' 3.12' 3.01
t i :
3.85
4.21
4.75
i
11.46 '32.86
t
t
3.26 ' 3.83' 3.97
.79' .71* .97
t i
4.34
.49
4.64
.43
4.91
.16
16.63*41.58
5.17* 8.72
i
3
.1
: Davis
foot of
IB increase
xre set
)f plot B
Decially
? content
i the soil
discrep-
3 for. A
b C became
accounts
by plot C
Lty after
st were mois
likely that
lot G by re-
itational wa
tione till
irrigations
stween the
i, in the
V.IS
'20
o 1 :
; ?c.
w ;
v.ss 'oo. a '
II 4
i i
ox.a'es.is 1
I
I
!
_ |
I "I
.' SS. . '
. '35, .',5*.
5. IS '
t ' dS..
i
!..' 3S.
.
t
c .
.
56
Experiments at the Agricultural College at Davis
The amounts of water held at each foot of
soil before and after irrigation and the average increase
which were found for the various applications are set
forth in Table XIV and Figure VIII. The soil of plot B
being finer in texture than that of plot D, especially
below three feet, accounts for the higher water content
both before and after irrigation. Variation in the soil
of plot B is probably the cause of an apparent discrep-
ancy in the relative amounts of water accounted for. A
comparison of plots C and D indicates that plot G became
drier before irrigation than did plot D, which accounts
for the greater amount of water being retained by plot C
since each plot contained about the same quantity after
irrigation. In plots E and G the upper six feet were mois-
tened to their full capillary capacity. It is likely that
the clay loam stratum of the seventh foot in plot G by re-
tarding the downward movement caused some gravitational wa-
ter to be held in the fifth and sixth foot sections till
the time of sampling. The effect of the large irrigations
of plot G is evident in the great difference between the
moisture contained, before and after irrigation, in the
siicf bete no id 63 Jit 1 'igctl-s 6ns S'lolscf iioa
-solloqjs ai/cliav Sitf iol Jbm;o1 s'isw lie '
^ orf? .IIIV 9i/j^i'5 ens VIX sIcfflT ni
39 ,0. iolq 'io cterfcr njSiii siL^xad' qi.'rcanM -Tt:
*^ . -
. 'isiBw igrisJtfl adcf xol actrtwoooa ,^93! ss'irii wo
. . ' '; s.1. nolcfeii^V .noi-Tsgiiil TacMa Dxts siolad i
- ) tfnsiflcpqs HJS "io aai/so sdi vlciucfoTq aJt Q' .d'olq
- fo'l bactnuoooB i9d".sw lo sctnwoiTtG sv.td'olai sfll ni v
- f ctolq d'BzW .aad'soibnl C ana D aoolq Ic noai-.
-
J 5 Y^ bsnls.ts'-i gniscf necfov/ lo dra/o."afl n
.fl Y^i^^ 8W P Oi~n.jsa sri-j" J.uqcf^ bsnlBcfnop dx.
:ow J33'i xle tsqqy odd" O btis 2 s-lolq al
xi 2i cfl .vctlosaso ^'iBlIicso II.f/1 il
.... .
57
third to sixth foot sections. The twelve inch irrigation
of plot G caused slightly greater increases than the nine
inch application of plot P in the second to seventh foot.
The upper six feet of the water content curve
in Figure VIII plotted from the averages in Table XIV are
based on 294 borings; the section seven to nine feet is
based upon 120 borings and the depth from nine to twelve
feet represents averages of 48 borings. Adams summarizes
the results obtained as follows:/^/
"Not counting the experimental plots at
Davis and Willows, moisture determinations were
made chiefly on 15 fields, of which 13 were of
silt loams or clay loams. In the case of all
but one of these loam soils, for which one the
full capacity of the soil to retain water was
not satisfied, the average quantity of irriga-
tion water retained per irrigation in the upper
six feet of soil was equivalent to a depth of
only 4.51 inches, or only 52.6 percent of the
average individual applications, and only .72
acre inch per acre per foot in depth of the
soil. Although the roots of the alfalfa pene-
trate in these soils to a greater depth than
six feet, it is plain that a considerable por-
tion of the irrigation water went below the zone
of greater root activity and was largely or whol-
ly wasted.
Considering the quantities of irrigation
water retained in the upper six feet of soil for
all of the field for which soil moisture deter-
minations were made, it is found that the aver-
age quantity retained in the lighter and more
permeable soils was .92 acre inch per acre for
each in depth of soil, whereas the clay soils
absorbed an average of only .37 acre inch per
each acre foot of soil, or at the rate of only
.axfold-oss tfool rttxia oA biicfcf
lo
.'.B o* briooaa d
9Visw
aw ad*, to ctsel xle i^qqir
nl asgsisvs sii* moll bectd-olq IIIV eiwsW nl
ot nev?a noWosa ecfet jagnitocf ^es .no baaed
* aoln inotl itfqefc 9ii* 5ns a^nliocf 021 aoqu
antsbA .a^nJttod 8^ lo easftisvB scTn&aaiqsi
' a^olq Isctnsmiioqxs sii^t
.ilflpi&*ei*) aiw^sicm ^swoIiiW ferns
si377 SI rioiiiw lo ,abl9Jtl 21 .no ^Ilsirfo
Ii;' lo saco srl^ nl -atttfiol YSlo -10 amool ctl
-cmo ;Ic>Mvr -fol ,Blioa maoi 9aorf-')- lo aric
j8w *xe^aw niB*ei oct lioa srCct ic ^lo^qJbo 11.01
-jnJmi lo Y*i* nBU P QB^av 5 rl * -.ba
iscqju sii.-t nl oolisaiTSi r ieq b9fiij3*3 f i
j? oct tn3lfivl-yp9 saw lioe lo :
-
10 B.Ct
s
.IiO3
-
58
2t acre inches for six acre feet; due to their
great imperviousness in their present condi-
tions. In the surface foot, however, the
light soils retained an average of I.o4 acre
inches per acre foot of soil as compared to
1.71 acre inches per acre foot held by the
clay soils, this being in accordance with the
well known fact that clay soils, when once
thoroughly wetted, will hold much more soil
water than soils of coarser or lighter tex-
ture.
Averaging the quantities of irrigation
water retained by each field for which moisture
determinations were made, it is found that the
maximum quantities retained per acre foot of
soil per irrigation were 1.02 acre inches for
the silt loams with fine sandy subsoils, .75
acre inch for the silt loams without fine san-
dy subsoils, .78 acre inch for the clay loams
and .49 acre inch for the clays.
Considering only the moisture determina-
tions from the surface foot of soil of the 15
farms, it is plain that, in the case of the
typical silt loam soils of the Sacramento Val-
ley, single applications of irrigation water,
exceeding depths of one to one and one-half
inches per foot in depth of soil it is necess-
ary to moisten, accomplish no useful purpose.
While the typical clay loams and clays of the
valley will retain against gravity in their
normal growing condition as much as It 1 3/4
acre inches of irrigation water per acre foot
of soil, over and above the amount normally
found in such soils under Sacramento Valley
field conditions, that amount of irrigation
water will not be absorbed by these soils un-
less it is applied very slowly.
The wilting percentages for the Sacra-
mento Valley soils under investigation ranges
from 10.35 in the case of the silt loams of
the experimental irrigation tract on the Uni-
versity Farm at Davis, to 16.59 in the case of
clay loam on the same tract. The average wil-
.
hi -s.
,^ . _A.X -< W **-j*.^^
lo ctool 9*108 iQq.asdoni
; Jool 9ios isq i l?.l
.^.j." . . JOOB rtJ gni^d alxlcf ' *allo_p ..
e>r fr ve is i : f r-o^i
, :t rloc/m blori II1
"1 ic 1S8TU500 lo'alioa
- brtfjol ai d"! ,9i)ffi a r iaw
j o : -10J3 ieq LaniBd'9 r i aslcJ'icJTtsi/p fawnilXBm
10! 36iloni 9103 20.1 ais aoiiaal'iii iaq Iloa
oV. 3lloacfwa ^fcrusa ariil rttlw airmol His edd
-/lo ail* ici rioiil S^OJB 8V. .sllosdwa
-.
51 sn'd- lo'Iloa Ic ^ool 90 situs erli mo-il
d^ lo 33flO d^ 01 ^ail* rtielq el ^1 8Rrxa'
amaios^ 9i lo aIoB...na'ol ills taolq^
HoJt-tBgJtui lo anoi^soilqqa eAgala ,
anc 5r^ anc oJ suo lo siUqeb slfiisec
al Jl 1102 lo tfJcreb nl dcol "isq ..
q iJJlssw on cEsilq^oooc ^jtaiom o^
rf^ lo s-iBlo bna airusol \-B!O Isoiq^ s;*
"ilsrict nl ^Ivs'is tfenisga nifivtei lliw
^\3 I il a a iloum sc |otibooo salwoig I
1 9ios i 9 q i*flw rrcJt: Mil Ic aaiforci e
3 'ISVO ,1
'
'
i o ci
le ad '
i saol
59
ting percentages for the several types of
soil under observation were 10.65 for the
silt loams with fine sandy subsoils,
15.12 for the other silt loams, 14.21 for
the clay loams and 13.06 for the clays.
The approximate quantities of water neces-
sary to apply to thoroughly dry soils of
the types listed to bring tne moisture
content up to the wilting points given are
in inches in depth per foot of soil, 1.5
for the silt loams with fine sandy sub-
soils, 2 for other silt loams, 2.3 for the
clay loams and 2.6 for the clay. The op-
timum percentage of available soil mois-
ture for Sacramento Valley alfalfa soils
over and above the percentage at which
wilting occurs, seems to average between
4 and Q%. This is equivalent to depths of
from .6 to .9 inch of irrigation water per
foot of soil for loam soils and of from .7
to 1.2 inches per foot of soil for the
heavier clay loams and clays.
Alfalfa planted on very open and very
impervious soils should be irrigated more
than once between cuttings. This is nec-
essary in the case of the open soils because
of the inability of such soils to retain all
of the moisture needed to mature a crop, and
in the case of the impervious clay soils in
order to accomplish deeper penetration of
the irrigation water into them. In case of
the latter soils it is very desirable that
the moisture supplied by winter rains shall
be supplemented by irrigation water suffici-
ently early in the spring to prevent drying
out. The frequent use by irrigators on such
soils of a soil auger is to be urgently
recommended, the investigations having demon-
strated that penetration of irrigation water
into the clay soils is very much less than
irrigation usually realize.
It will be noticed that the curves plotted
from the foregoing result do not bear the same character-
10! e
w'rtcjtd' 'o lebnu
dtflw atr_ecl 31 la
lertfo srtt iel SI . 51
1 ' '--ol ^sJo 3-:^
aB0p sctKirdxo'iqqjs orfT
; oct ^Zqqc Oo visa
.u novi.. afrnloq -^liJlivr srW ocf qL-
a. I , r'ios 'io *ool i3q xWqsb nJt a^^ro.nJ
-cf.f/a ^fcnjsa anil fitl^ arose I *J !e *rfd
aclj tol S.2 t arrtol d-Ii^ 10'
-GO srfT .vBlo sd* 10! 8.S bns aniaol ^ei
-eiom lie a sid^Ixsva lo s
allca slisllB ^slicV o-JriS
ioinv: ^B o^B^naoisq ail* dvods brrs 'i
naow^sd sgii^ava cj smase t aiwooo grtiJ
'io arld-qsb o* toslsvii/pe al .3irfT .^3 6n--i
sq --led-sw nold-egJt-iii -lo doni 6. o* 6. UKrrl
. "moil Io SOB sliQe nTBol ioi lioa 'Io
--ic'i lioa Io -creel isq asifonl 3.1 oct
fteqo "'f^ v ao bsf^-q
3-rofti b 9-^375 .ttii scf ftlja:bi-a aiioa
JLioa naqo srH Io 9830 ?^Ict rJ
i ocr alioa rfe.aa Io ^' lie
fene t qorfo o etifctBt od" bebssn si^J-aicin
nl alioa T ^.elo aL'oivisqrrsi Silct Io SSBO 9dJ
"io noJttsi*9nq laqssfi dsilqmoooa bet isbio
io 9-iG o al" .fnsifd odnl a^ctsw noj
do i/a no a
.
;tcic 2 '
fYft- . '
60
istics of an abrupt diminution of soil moisture at a
fairly definite depth as the experiments quoted previous-
ly did. The explanation of this is to be found in two
factors'. In the first .instance the initial water content,
especially at the lower depths, is much higher than in
the first case, where practically air dried soil was used.
This will have the effect of decreasing appreciably the
frictional resistance that the irrigation water has to
overcome in its downward penetration, since the initial
water distributes itself as films round the soil particles.
The water that is added therefore is under a much smaller
influence of soil affinity and the other film forces.
There is therefore a greater tendency towards the sliding
off from the already existing water films. The higher the
initial percentage of water present the greater is the
amount that will penetrate downward.
In the theoretical diagram, if the initial water
percentage is kf.. the amount of water that will be dis-
tributed uniformly is cde, whilst if the initial percentage
is kg, the excess amount of chj--and the resulting curves
before and after irrigation will be as shown- -the two
curves converging with an increase in depth. In view of
the results obtained from these experiments and the assumed
lOKi ilos lo nol^ualfalo (J-qwids OB lo ED Ida!
-3juolV9tq berfotfp acffls-ul-i 3.^x0 sxio se fl-Joso a^iotlsfc ^1^1
owd- nJt.uouol.ed ctf ai eiitf lo flottMWlqxa aJT .Jblfc ^1
d-xts^noo is^xvff tiitini stiJ aons^aai. ^siil 9lc> nl
nx rtsii^ 'isri^lxl riowtft al ta^Ilosb tsvrol 9dJ ^ta -^iiclosqas
ii- asw lloe belrci)" iJt ^IIaol*oai 9iadw -eeao ia-i
Ylcfj3io3iqqs 4rilasa r i ; 39& lo uos'ils .scl^ evsil lliw alxfT
asxf t3?BW nol.is^jtiti sxid- tc-IcJ- 9oxr.i3i39i isnoJtcfrolil
JIrti edi son.ta , noi.-t^ij-sneq 6ijewnwo> adi nl s.:.iooTfsvo
HOB ai-d ont'o^ a.^tlil as llsail 39*.oclli,iaib ^actsw
/3.Ti3 rIo0f : T Q isbnw ti g^c'Iana^ bso;:.-- si lo-rld" aactfiw erIT
.39010! fitl.fl i&r.'-'to c?/t bn-5' ,;?! I'll 3 Iioa lo aonDwJlni
'lia 3iW d :.>!; 7/0 ct -.on^brtS-} rrcteo c,a A siolsigiid" al o-isaT
j-I^irf edT' .arrrll'i tel^w v'^^slxe '^Bg'ilfl 9;fd- moil .Tlo
.i.i al Tscf '-3^3 -srfd' d-nsaeaq isd'^w lo s^ed-aao^eq Islcflnl
nag IlJTw d'arlcJ' jnwc;,t8
q Lsid'lnl artt 11. islirivr ,e&o al ^lnrrollnw fis-tj/dlT:^
30V1UO ^nltl/jaei sifct bn--{,rfs lo in.croffi'; c-.asoxa siict . ^3i el
lo w.9lv nl .rf^qab ni aeaaapnl. n T ^tl"ji9vricc a-avitro
60a
theory it follows that it is not the soil moisture which
distributes itself according to the root system of the
crops, but it is rather the root system of the crops that
distributes itself according to the distribution of the
soil moisture.
There is a very mistaken fallacy abroad (especi-
ally is this the case in alfalfa) that the soil should be
wetted to the depth of the roots, and alfalfa being deep
rooted, sufficient water should be applied to penetrate to
that depth. But since it is a well known fact that the
roots rather distribute themselves according to the prevalent
moisture, it follows that any excess water specially applied
. for deeprooted plants, say below the sixth foot, is practic-
ally an entire waste. It has been noted by various authori-
ties that on an average the following percentages of the en-
tire root system for alfalfa penetrate to the depths indi-
cated.
1 foot deep 27 percent
2 feet " 43 "
3 " 12 "
4 " " 10 "
5 " " 7 "
beyond 5 " " 1
-T-o-Dcrsg) baotdB vosliel aa^B^fc-ira --1^ * si
i '\ vj d"O.S'X CIWOpl Ii3tf S 3X
9x1* o^ ^alb-iooos asvisancs
Ilciceqa t9ctsTr aaeoxa
al . ^oo'i dcr:<J:e sii.-t
yd bs^on rtaed aed ^1 .9
91
B1
II^HRSI
mm\
51
CHAPTER V
CHARACTER OF SOIL AND SUBSOILS
Apart from the actual texture and structure
of the soil, there are various conditions that are met
with which influence the application of water to a very
large extent. Foremost of these is the layer of hard
consolidated soil particles, known as hardpan. See Fig.
IX.
Hardpan is the result, to a large extent, of
soil weathering. The finer the particles are broken up,
the nearer do they approach that class of soil termed
clay. The particles are subjected to percolating water,
and the soluble constituents may be taken into solution.
Thus we have solutions of sodium carbonate and various
silica salts, associated more or less with other products
of rock decomposition. It is in the surface soil that
these solutions are chiefly formed. And according as
their descent into the substrata is unchecked, or is li-
able to be arrested at any particular level, whether by
pre-existing close grained layers or by the cessation of
the rainfall, the subsequent penetration of air and evapora-
tion of the water alone by shallow rooted plants, may cause
the accumulation of the dissolved matter at a particular
9-I.J . '
IC f| : . Cfn<
:xc3 o<n
a^'oiisv bns
s i3^o rfdlff aeal'ic
lioa sosliwa erl^ nl
-slo ^srfd foeoiQ.qs ^srtd
i bs^oscfwa 91^ asIpijJriaiii $rIT ."^ali
62
level, year by year. The action is largely accentuated
by the filtering action of the minute clay particles
which have originally been washed down. The water, charg-
ed with these minute particles, precipitates them whilst
passing through the accumulated layer already laid down by
the percolating water. It therefore is of an accumulative
order, the greater the amount of colloidal matter washed
down the more extensive will be the filtering action and
the thicker will be the resulting hard impervious layer.
Once the layer has become impervious the descending water
is either used up in transpiration by the plants or by
evaporation into the air. The dissolved salts are hence
crystallized out and will act as a cementing agent, be it
siliceous, calcareous or ferruginous in the consolidation
of the accumulated layer. The ultimate result is a hard,
consolidated layer known as hardpan.
According to the cementing agent, hardpans
will either be an iron, lime or siliceous hardpan. The
iron hardpans are exceedingly heavy and much more compact
than the lime hardpan. It has the fortunate characterictic
that when once broken up by dynamite or some other method,
there is but small danger of it reconsolidating. On the
lime
other hand/nardpan, which is readily recognized by its
lighter colour and by its rapid disintegration by dilute
ew fissc T^wn^o averi rfoifiw
ild 1 ilctir bs
>rfo <=< e .a ' >''
> O 1 VJ M * J - *i
.isd'ew
flooA jjnis ori.t 3d IlJtw svisne^xs sioia srftf xwob
oivisqjni Mi-n 30 Wins 91 srf^t sJ Illw
nsoaai) Qrf* aucivasqmi emoosd a
^Cf -io s^nfllq 9^ ^J noi-tJB-xIqarwi* nl qw b.au i-arttls ai
sonl 9iJ3 a*Ifls fiovloaslb 9-T
il ecf ^osa si*nsnteo B SB C^OB
A*. \\>V- vi"V.
feilosnoo wtf rxi Bflo^*wl- r ro auoe
..Msri a el JlJre'&i 9*raJt^lM grfT .I^B! Be^sXiR^ooB ei!* lo
.nsqbtan ae nwcml -i^^X b*BDlIoaiieo
.*asBe inl^neweo sd* o^ gru.
auceolXJ^a no will ,toil as d writfls Jilw
-oo^Y* af'R rOll
...-TB ^vBsn vi
~jj;j"xoi S^ afiil ^1 stftiX 93-3 *-
.^TA. x '-o-s- t-ttismrfs :o f sono iio:!^ ^
63
acid, may be reformed by the descending water in time to
a second hardpan layer. The iron and silica salts, once
precipitated out, do not readily redissolve.
It is fairly well established that the lessen
-//,' -.,>-
the rainfall, the smaller the depth at which hardpan is
found and the softer in texture it probably will be. In
general, hardpan may be encountered from twelve to twenty-
_
four inches below the surface. If at a greater depth, it
will usually be due to the formation of a more recent soil
layer on top of the original surface.
It is evident that when such an impermeable
layer is allowed to remain near the surface it produces
serious results.
,^,f .
(1) By the failure to absorb the greater
part of the water, thus permitting it to flow to the lower
part of the orchard and out into the adjoining lands, (2)
by facilitating sideway surface percolation from the fur-
rows and exposing a greater area to evaporation by the heat
of the sun,(3> by holding the water near the surface and
thus causing its loss by evaporation before the soil is
cultivated, (4) by preventing access of the water to the
roots of the trees, if any, lying below the hardpan, (5)
by preventing proper ventilation and aeration of the sub-
soil.
ef> extJ ^cf ber.nolsi sd ijs
u'.; o
j?l ciid dnrf-t fostfal-I a'edss liaw ^L^iffl 2!
el ruaq.b'xs.u riolifv; do iidqaJb srid naJIiiwa ed*- lllali
01 . eel lllw vlcfodoiq dl aif^XBd ril isdlca a^i
-ijdne^d od 9v4*v/-d .tto'i'i bs
dl ,i{jqsb Tsd'&s'is 3 d,-j 11 . eoe'n^a std wolacf aarlonl iirol
lic<3 drisos't 9*iont s lo rtcid^fmol arid' od swb scf vilctfew Illw
'iiigiio 9fd lo qod .'
iid dns&ivs al. dl
:nan nisnts-i od 1 ftswoIXs al
cfioadc od" ^iilici and ^d (I)
iswol arid oj well ol di gnlcJ^lnnaq awxid t i9^sw arid- "io
(Si \abrxBi 3nlnlc'.;/ ^xid odnl dro bne bisrioio erid lo
-iwl slid nwil aci: ..'looieq' 90*lii/a -^waiile snidB^tllO
-florl arfd" -^cf nolcraioqev* ocf saia isd'aeia a gfllaoqxe &no
d* isen lodsw eta- gaib oil ^d ^5K
ft:
al IJtoa eitt eiol-ed rxoidsioqavs YCf saol a*l gnlax/ao e.
od lad's-* srid lo a
.loe
64
Soils underlaid with hardpan should therefore be
irrigated very continuously a more moderate quantity more
frequently applied than for deeper soils being the best
practice. It may often be profitable to blast occasional
holes through the hardpan to serve as outlets for the excess
water that stands on the hardpan. Such blasting, to be ef-
fective, should occur frequently, in which case the process
becomes highly expensive. Before undertaking this measure,
it certainly is advisable to make a thorough examination of
the extent of the hardpan, its nature and depth and the type
of soil underlying the layer. If underlaid by a heavy sub-
stratum like clay, blasting is inadvisable. The extent will
not so much be that of opening the soil by cracks and crevices,
but rather that of forming a watertight compartment, the clay
being compacted all round by the force of the explosion.
The effect of the texture of the subsoil on the use
of water is quite material. A heavy soil strata occurring at
depths of three to six feet is of much aid both in retaining
moisture and in the cross percolation of furrows. The heavy
subsoils are in general not entirely impervious to water, the
irrigation water penetrating them but the .rate at which such
water escapes by deep percolation is materially reduced so
that the moisture is held for longer periods within reach of
gcf
>ii/cfe nsqfctBa rfd'lw
9 f iont e
*39d arid- ^nled eIJtos leqssc 'iol nsiid- >allqqj3
iBnoiaeooo ctasia' od- slctectlloiq 9d uecTlc -^sm *1
aasoxs sd$ 'io1 sd'al.iwo ae avtaa act nsg.En.sd snct
-Is 9d ol ^grtid'ajsicf rfbx/C .K&vjjnati adct no ar-nsda
eeioil
eaao ;
nl
iwooo
lo
airict
>HB
t evict 09!
asmooscf
xfeiJo^or;d e
ocj- alo^s
a
s/ct 'ic drisctxe
lioa lo
lo d-tulj so'
LTic'i 'io J-BiI
ilfi }9ctoeqmoo
os
-dua ^vj39il ^ Y O/ ii-jsiisibnj/ 11 .
IlJtw chisctxe ^:fr . slc^iaivb-anl al
,aeoi:v9 r ic> feris a:-;oe'io ^d 1." :t
valo 9ii3- , d-nsmJ-ijaqnioo d-iisid-isctfiw s
.nclaofqr.e 9ili 'ic 9010! s&j
9ao' erfcf no I^oarJ^a OiU "io err^xect srict Ic Jo9lle
j"fi ^niiiijooo act_vjya lies *^ve.9d A .Ici'jcsd'a.Ti sctiwp al
^ninJBtsi ni dtfod &!B rioJOTT lo E! igel xla od 9Sirld; lo
il arT . swoiitfl Ic nclcH'Ioo'iaq aao'io fct fli bne
ts*jaw oct awciv^aitrl .^Xa-ildrsa ^on Isiaxies ni ois alicedtra
lo
-30
ic
-isritf
65
the plant roots. Such a condition is more favourable than
an impervious layer like hardpan as in the latter case great
care is required to prevent water-logging of the soil.
Where there is no heavy subsoil to assist in cau-
sing lateral percolation, the ease with which moisture can
pass downward lessens the extent of lateral percolation and
a closer spacing of furrows is required to secure an even
distribution. A large part of the water applied may also un-
der these circumstances be lost by deep percolation in the
upper part of the furrow before the water has reached and ir-
rigated the lower portion.
When the soil is underlaid with gravel, or if gravel
seams pass through it within ten feet of the surface, the nor-
mal distribution of the soil moisture is disturbed. If gravel
is mixed uniformly with the soil from the surface downward, or
at varying depths, the soil may be looked upon as being contin-
uous so far as the distribution of water is concerned.
When water, moving downward, reaches a layer of loose
gravel, the descent of the moisture film is first arrested,
then the film is -thickened until the lower soil pores are filled
and, if irrigation is continued, gravitational water drips from
the soil into the gravel below. The water which thus passes in-
to the gravel cannot move back by capillary means and usually
narf* Idsii/cv.sl eiora al noicriDnco rio8 .etfooi Jtnslq arid
nl as neqlii&ii 6iiH te^al awclvisqml lie
.Iloa sr# lo ryiissof-ioJaw tfn^vefq o bgiltfpdt si eiao
-wao-nl d-elaas o$ Ileadwa xvB^xi on sJ: siarW e-xerflT
HBO siijtfaloai doliiw xiJxv eaa afltf .naiifiloowq Iflne*2l gnla
>ns noWalooisq XBisctoI "lo Jaetfxo arfd ansaasl fctawdwoJ aesq
H0vs nfi etjjose oct X>eniup9x el ewo-i-utt ^o anlo^qa teeolo fl
<
-nj; oals ^flm bellqqe isctsw edct lo *iaq egisJ. A .
sri^ nl noWe-Ioo**^ qesb ^ ^20! eJ eoon^a^o'ii
-il bnJ3 bsrioaei aaci locta.w and. o'lolocf Yron-ro't 9iU "10
is we!
11 ^o t l9Vi?ig rlcHw blel'iabrtc/ al l.'-.cs aud"
-ion oi-y ,90BliwB 9r lo C5-S31 ne* nlildiw -11 ^g^
I3V31.S II .bscfiurfalb 2! e-utfaloia lioa eiW lo riold-i/dii^s-lj
10 .bi.ewrrwofo so^/lii. r a 9;ii nto'M iioa yiii ri^lw .Ylirnolim; baxlm el
ai npqv befool ocf -?Btn Jlloa srtt t sri*qofj
a:: is^isw lo nclludlid-alb afit* ae nsl oa
saocl lo i9"i-3l a ssrioan .biawmrob anivom ,id-sw necIW
.bs^aoii^ d-aill al fftlil 9urtaic0 otl* lc tfrteoseb exit .
bellii a*j2 ayioq Iloa i9*ci 94^ IWnu beaa^ol4J- al mill
noil aqlib IS^BW I^aodd^lvsi^ ,b9WHl<tnoo -el nclis^liil 11 *
-rtl aaaesQ awrfi told le^aw 9ilT .wolsd iavGig DriJ orfnl
boa BflBaic 3 &<* VP^ Jomiso levBi 3 ertt o-t
66
drains away into the subsoil and is lost to the plant.
Soils, in which such gravel seams occur, should
therefore be irrigated lightly. Not enough water should
be added to allow any part to move into the subsoil. Un-
der such conditions more frequent applications of water be-
come necessary.
oct ctsol ai fens HoacUra erf* o*nl ^aws
dowa a'olriw 01 ,ello2
svom o.J ^-xaq ^/IB woXI* o^ f>sS6fl 9d
lo anoliftsllqqfl d-^swpeil enom anoim>xioo rio;ju -^9b
.iKaasosn srnco
67
CHAPTER VI
EVAPORATION, PERCOLATION AND SURFACE WASTE LOSSES
The water applied either by precipitation or by
irrigation to the land is disposed of in two ways: part
of it runs off and is wasted, and part of it soaks into the
ground. This latter part is disposed of in three ways (1)
by plant transpiration (2) by evaporation and (3) by per-
colation.
In irrigation it is the object to reduce the sur-
face run-off, evaporation and percolation losses as far as
practicable, thereby keeping a maximum amount of the water
applied stored in the soil within reach of the roots until
such time as it is needed by the plant.
Evaporation. Immediately after the water has been
applied to the soil, evaporation begins at the surface and,
in time, if not checked, the loss in moisture will be felt
throughout the root zone .
The movement of water, as' already explained, is
from the thicker to the thinner water film or from the wet-
ter to the drier parts of the soil. When therefore the im-
mediate top layers of the soil lose their moisture by evapora-
tion, there is a tendency to partly replace this loss by an
upward movement of water from soil particle to soil particle
from the wetter subsoil.
IV .JO
dia. :e\'w owd nl Ic baaoqs a n*
eiq v- i9*- r di9 & isdaw
d. od-
add otni a^oa it lo *isq bns .bsitaew ai 5ns llo aaxn *i
U) a^w 991, i* ni lo Dsaoqaib a I ctiaq ledrfal sixfT
-isq ^ tS) bns nciiaioqBvs ^d (S) ' Hol^ailqerwi* *nslq
-IJJ3 srict 90-ubsi od- cro3f,cfo arid 1 ai di aoide3itii ni
BS IB! SB ssaaol no'ld-jBloO'isc bnc ncl-^aioqavs /
IQ^BW su'cr lo. *nbota nujfiiixam a gnlqeeil ^cJe'ierid
3^0 ^
aitt '^d bebssn ai 3i SB siplct rlo^s
t bns soc'liui 9dd dj sniped noidsioqsvs ,Iioa 9xJd od bsilqqs
d-131 sd II iv; siirfslom ni saol oiid ,bsj(oerio ^on 'ii ,emil ni
ai ,benir:Iqx9 TfbB9il3 ae iodaw lo dnsmevoin sdT
r * f A i*^f- r!'*^ r* fS^* fff^iff *T
f sild mo'i'i 10 ffdi'i lodew isnniiid sad od is^oiiio saff
-mi er& eiolsisrid- nrIW .lioa arid lo sd"isq i^lib arid od id
? d 9'iwdaiom lisrld gaol lioa &d$ lo ais^s! qod
Y5J >aad ^ ai
>drriY lo J ORt
.:v r :.i
68
As evaporation proceeds from the top soil, the
water in every soil layer diminishes to the full depth
of the root zone. Dr. Widtsoe likens the action to that
of cotton packed loosely in a box. By removing a small
quantity, the remainder expands occupying the same volume
as before, but in a looser condition.
In soils a similar condition is met, when part
of the moisture is extracted, there is a thinner moisture
film condition throughout the entire mass. But the de-
gree of drying out is not uniform throughout the soil. It
is only in the topmost layers that the process may extend
to such a degree that the moisture film is reduced to a
minimum for capillary movement. As the {tS/ff/ffo- capillary
point is approached, the upward movement becomes more and
more sluggish, and it is very difficult to reduce the low-
er soil layers below this point even though the upper lay-
ers may have a considerably decreased moisture content. To
stop this upward movement and thereby the surface evapora-
tion is a chief consideration in irrigation farming where
water economy is a vital factor.
The nature of the soil is of considerable impor-
tance. The finer the texture of the soil the more rapidly
will be the upward movement of the moisture to be changed
-fto
J3 rxi
a
istinirict H ai sisrit .b
-sf> eii^ *ua .aaflfli sil^ns adct ^worf^wcrrdj nol
d-I .lloa fjjtf* *or3J/oid-d- iRiolJUoj d-on ai ctwo '
l mill
i>n- 91 OKI siftmo
- vo I S'itJ ?0!/f5S'i oci" j'lt/ol'iilD ""(T^rsv ax -I
--;el 'i9c A ci/ srl^ rfejjoifd 1 nsv? Snloq el
of .inoctnoo - Bob i^^^s^i 21 " 00 G '
l nl
.lo^asl IJB
ISIiEiESES
mat
m
mm
mm,
m i
n
!n
/<s /a to ste e* as as 30
w.
mmr^mu
ililiil ' wm
II
.
,..''-'
69
Into vapour. The darker the colour, the more heat it ab-
sorbs and hence the greater the evaporation. The richer
the soil is in soluble salts, the slower is the evapora-
tion of water into the air.
Of the meteorological factors, the evaporation
is most largely influenced by the temperature, sunshine,
relative humidity, wind and rainfall. The higher the tem-
perature, the more rapid is the conversion of water into
v/ater vapor. Much more water is lost from a wet soil on a
sunny day than on a cloudy day. The drier the air, the
more rapidly will the air take up water vapour. Winds,
likewise, exert a strong drying efi'ect on soils, especial-
ly in the case of relatively dry wind. It has also been
shown that the wetter the soil is st the surface the more
rapidly will be the water evaporated therefrom. The evap-
oration of water from a soil varies as the initial percen-
tage of the soil moisture.
The results of the observations at six stations at
which evaporation experiments were conducted under Dr. For-
tler are shown in Tables XVI and XVII. The saving by cul-
tivation is also clearly shown in Figure IX.
loo srfct isiteBb 3iff .li/oqev odrtJ
&n"cf isJ-flais ft eorxeri fens adioe
$ tafias 3lcl;;ioa nl si .Ilos srtf
.lifl arl;? otfni isctew lo no let
BO igoXOIC SJ-9M 8ftt 10
vet be 0x191/1 In Jt *il3il etaom al
^ ana bxilw ^cJ-lfclntucf
fioiaisvnoo arid- al biqa-i siora 3ilo , a^/
moil a<iol ai IOJST/ siora do.o-M .'toqjev
18 lt> srfT .^so i^wol o s no nail* \'b
qu ejle* 'ila arid- Uxw ^iblqai 9-ront
'inoi^a s d-isxa .
' o'alfl aBil $L . Dniw v;iL> ^Idvi^alei lo seso
arid- d-^ ai lioa eri./ 'isdMsw 3ii^ d-srld- ftwoxle
jy OS^B^OqBVS 'Xdd"BW SXitf 0d II 1W
as saiisv lies B nio-tl IS^BVT lo
a-'i.oitaiOiTi lioa sric
i*B\xia d-B arxoilavisacfo 9ifd lo aJIx/8d'i sxfT
- . Cisr ft 'JT \ * p< -" '-^ ^r-f "sn Y " " " .-r^ r{ f> ?
:&& eJH .IIVX bxia IVX 3 nl nwoxia eiB ieid
al xiworia vi oala ai.nol*.
70
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72
The process is not difficult to understand.
Water moving toward the soil surface must pass from parti-
cle to particle through 1iie various films at the points of
contact of the soil particles. The smaller or the fewer
these points of contact, the more difficult will be the up-
ward movement of the water. When the top soil is loosened,
the points of contact between the loose soil above and the
compacted soil below become reduced, and hence the ascend-
ing water finds it difficult to pass through the fewer
points of contact. The more thorough the cultivation, or
the fewer the points of contact, the more difficult will be
the upward movement and the greater will be the reduction
in evaporation losses. It therefore follows that the deeper
the mulch, a greater saving can be expected. That this is
the case is shown by Table XVIII which shows the average
losses by evaporation from a free water surface and from
tanks with mulches of different depths at five different
stations.
ai aaa
e lioe artt biowocJ- gaivom
1; q 9rtf rffi- amlll awoiiav srr .rfsuoiiitf aloi*naq
73! acfi 10 isllsma erff .aslold-^q 'lioe erf* Ic
-qu 9d* ed Iliw d-Iwolllil) siora srf^ ^oadrioo lo . s^nxoq aa
^dsnsaool al liob qorf neclff' .'-isd-aw sxlct lo *aravom
srfct bna SVodfi Iloa aaool srld" nsswd-scf ctofitriGQ 1o aJnioq
smoosd 'wolac! HOB bsJ-os
19W31 9iid- dgjjoirict aaev oi d-Iwoi'il.cb rfx sfcnil isctaw
ic t noi^svJWIwo aild- rigwoioxtf eiont srfT .ctoatfrtoo
*I wo 111 15 9tc;n siij .d-oscJ-noo lo a-'tnioq arii
rW scf iiiv; i3*J9 r is 9^ & a ^ itnaflievoM
d av/QlIol ato'isisili ctl .asaaol nol^B'ioqava nl
ai aijtt dexfT .09^0-30x9 ad aso gnivoa '13*3313 3 ,iiol.vrit 9iicf
s^iova sifi aworie lioifivr IIIVX alefBT ^Q r rcworia si sao eii*
Bioil fjn^ soj3A-iira ia*i!w edil s motl noioflioq^vs -^ef 39330!
llb svi'l Je aa'*q?I> Jno'isllii) 'io a ado I urn d^Zw aatrtad 1
73
TABLE XVI 1 1 /
Period
.
Days
i
Loss from '
LOSS froir
[ Soil
1 No
'Mulch
i
3"
Mulch
5 "
Mulch
I g II
Mulch
Inches 'Pounds
Pounds
Pounds
Pounds
First
3
r~ i
.86 ' 9.6
i
1.9
.48
.48
Second
4
.95 ' 5.1
i
2.1
.56
.56
Third
3 '
.87 ' 3.7
r i
1.6
.63
.25
Fourth
4
.95 ' 3.6
r i
2.3
* .89
.43
Fifth
3
.97 ' 2.3
i
1.5
1.08
. 53
Sixth
4
.99 ' 3.1
i
2.4
1.73
1.07
Total
21
r i
5.59 ' 27.4
11.8
5.37
3.32
Equiva-
lent
loss in
inches
t
i
' 1.75
t
.75
.34
.22
ffable XVIII and Figure X show that from an open
unmulched soil surface for a period of three weeks the aver-
age loss was 27.4 pounds, which is equivalent to 1.75 inches
of water. The percentage saved from each depth is shown in
Table XIX.
naqc ns iuc'il tfBiicr v/oue X s^wgJ^ fo^ts IIlV>i
-IJVB sxi^ 3X95W 3a E t r ;cf lo boii-w-q TO! eoal'iijje iioe- 1
xe<i
'
1 1
1 61 ' ? .8 '
>j J_
i i .
*"-o ' 3t
<j J3*liT.
.
1
95 . 1.2
I
as.
6. ' 3.1 ' ?- '
i i i
V8- ' 5 ' fi'ilifT
.*.- |
.2 ' 0.5
! 1
! 1
on r I ;s r ' ^ Q '
. _i. G i. vj *
ve. 5 ' Jt^ii^
i
vo.'i
22. |
SV.,t 1>.2 l.S
I K. i
95. c IS 1 L&3oT
V5.3 ' S.ii ' ^.V2 |
,
i ,
i t 1.
!
' -.. c
r>O
vy -f ' ?V f '
' I rtj- QRCJL
5V. i oj ^aeiavlwps ai rfojtriw t abowoq fr;VS BQW aaoi 33*
nwoiia ai ilJ-qefi .dose iucil bsvaa sssJaa^tsq exfi? .-istav lo
.XIX s.
74
TABLE XIX (9j
Condition of Sod
Evaporation loss
Percent of saving
on evaporation from
unmulched soil
~^
Inches
Percent of wa-
ter applied
No mulch
1.75
29.2
00
3" mulch
.75
12.5
57.0
6" mulch
.34
5.7
81.0
9" mulch
.22
3.65
87.5
The saving therefore of a six inch mulch and a nine inch
mulch varies but little and it is questionable whether it
is .economical to go beyond the six inch depth.
In localities where the available water supply is
limited and where the duty of water is high, conditions have
forced the irrigator to resort to methods of irrigation
which will result in a lesser waste of water than that of
flooding the entire surface. In orchard irrigation expeci-
ally, but also very extensively in all crops that are grown
in rows, furrow irrigation has been largely adapted. The
present tendency is to use deeper furrows than formerly
used. The reason of this practice is not far to seek, in
that it is quite evident that under such conditions a smal-
ler percentage of moisture will rise by capillarity to the
surface to be evaporated.
I
.
.
S.Q2
3.21
V.S
33.5
1 5 -
;i B 6nB riolxmt rfoaJt xie a lo
d- '9i9lw sltfanolcraswp aJt d 1 !' fin* eXWll
..dd-qsb rfonx xla add- bno^ed 03
al ^Iqqi/a laiaw sldsllsva orl^ yxaa
'io ctsfjj nfcit-l ista- i
JLogoxe nold-os
s n
3-i. :
ruarii
c .
acai
". ' ' ' D . J .
fl/rrenrf af ' rar/ws eff/o/Stf.
;:<?:"'
75
Tables XX and XXI give the result of the exper-
iments conducted by Dr. Fortier to determine the saving
of water by various depths of furrows. The tanks receiv-
ed a six inch depth of irrigation water, followed by a
six inch mulch as soon as the soil could receive it. The
results are illustrated in Figure XI.
-
rloni xie
76
Equivale
t-< f-3
O
CO c^
CO P
M
CD<jO>Olrf^WlOI-'
Period
g
ct
M
O
to
to
10
CD
^Wrfi-Wrf^W^W
I
CO
H-
P
I_U
K- 1
O
HI-'l-'MHJ-'HI-'
H- H) 4
y p JB
o o <+
P (D (D
tr*
o
CO
CO
.nches
rf^
o>
rf^O^MCftrooiM
o<i<jrooooo
to
*
Hi
*1
i
H
to
H M H- 1 H M W <O
H
*=j
M
O>
Oi
CDMt-'l-'J-'CDI-'I- 1
ioioioocnW-4rf>
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DJ
10
Ui
to
M
H M H 1 I- 1 tO W D
o >rj
(D (D
w u
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P T
et I
Js
H
CJi
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10
M t- 1 M M tO Ol
rf^totoa>i-'woi<D
OlOlOOCJlCDXIOl
t^
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to
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P
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M M H M I- 1 tO O>
o *d
^
4
Cft
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rf=>
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OOHOiOi^CJiO
CDOCJiCDOOJOO
& 1
CO
to
a>
Hj
c:
i
rf^
M H M H H 1 tO rf^
***
-3 . H IO CD M. Ol. -3 W
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0) CD
P 4
Ct 1
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irrows
t
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*
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77
TABLE XXI fr)
i
T
i
Loss
'Amount
sav-
'Amount sav-
'Amount sav-
'Amount
by
'ed over
'ed over
'ed over
'saved
evapo-
'free water
'flooded
'surface ir-
'over
ration
'surface
'surface
'rigated
'surface
'
t
i
'with
'irrigat-
i
'
'3" furrows
'ed
t
i
'
'6 "furrows
Inohe s
'Inches '
Per-
'Inches
Per-
r lnche s
Per-
'ifiches "Per-
i i
cent
t
cent
t
cent
1 'cent
( i
"T
T~
i i
Water
i i
1
1
i i
surface
10.46
t i
1
_ _
i _ _
_ _
MV
i t
1
1
i i
Flooding
1.25
' 9.21 '
88.0
t
__
_ _
_ _
i i
3
Inch
i
1
1
i i
furrows
.98
' 9.48
90.6
' .27
21.6
1
<
i t
G
Inch
i i
'
t
i i
furrows
.86
1 9.60 '
91,8
' .39
31.2
.12
12.2
i t
y
Inch
1 t
i
1
i t
furrows
.72
9.74 '
! t
93.0
. 53
i
42.4
' .26
26.5
' .14 '16.3
i i
-VBS
-V.83
-VB
asoJ*
jo 1 .:
:0 >3
99<il' -oqi
. itx/s 1 nci;
5.61
t i
1 __ ' -- ' 3.12' V2
i
.21' SI. ! S.lS'y
1 ' - ! . I
3S r SS. ! .2 !
,
0.88
o . OG
s.ie
t
soxfonl
6*. 01
06. e r as.
is. e cs.i '
1 nonl S
dcnl 3
rfonl
f awc.Tii/l
75
78
Percolation. Of all the losses in the applica-
tion of water to the land, deep percolation generally ac-
counts for the greatest portion. As stated 'before the
probable loss by deep percolation is generally from twen-
ty to fifty percent of the water applied.
As shown by Table XIV diagrams of the moisture de-
terminations on the alfalfa experiments at Davis farm, given
previously, for the various irrigations fifty-seven, seventy-
four, and fifty-four percent of the water applied percolated
1;G 5.52 6.60 '. 06 -.1
below the first six feet with an average of 68.8 percent.
Table XXII has been compiled for the various soils
on which the alfalfa experiments were conducted, showing
2.20 5.23
the loss by deep percolation.
.1 398G01 9do 113 10
-.-T-i ;"-"l' ~"~~i~~ ~J " _ r
'
'+ v* ^rra-rsns^ 3l aoWalooiaq qeeb Tjd 230! sldsdotq
me - J. j,j.j. *w
^m ocf ^
lom srf* lo au-u3Bl& VIX 3-CdflT ^ n^crfe aA
a i* a*na ra liaqxa BlIallB a^t no a
* ax lo cfn
8.63 lo asaw ^ ridiw' *aal xia * B all adJ
silos
no
79
TABLE XXII
i
Class of
Average
Quantity
'Quantity
'Percent-
Loss due to
Soil
depth ap-
retained
'of water
'age re-
deep perco-
plied per
by upper
'retained
'tained
lation be-
irrigation
six feet
'including
'including
low six
of sod
'probable
'probable
foot limit
'evapora-
'evapora-
Percent
'i
tion
'tion
'losses
"losses
i
Silt loam
i
t
with sandy
i
'
loam sub-
i
i
soil
15.02
5.52
6.60
' 45.9
56.1
i
i
Silt loam
12.81
4.24
1 5.52
1 41.5
58.5
i
i
Clay loam
8.78
5.50
1 4.56
i
' 52.0
I
48.0
Clay
4.72
"
2.20
1 5.28
' 69.4
30.6
i
i
Very heavy
i
Clay
3.67
1.06
1 2.14
58.5
41.7
i
As was to be expected the results show that the
percolation losses were rather heavier on the lighter silt
loam soils than on the clay soils. Percolation may be look-
ed upon as capillary movement of water aided by 'gravity, and
since any capillary movement is dependent on the texture of
the soil, so too is the rate of percolation to a large ex-
tent proportionate to the texture of the soil. Measurements
have been made which show an absorption on blow sand soils
ev
lo aa.elO
-9- S
-9 ' ' '*, b~ ... ~ L fl
xis KO ! 31 i.t X ;; G 1 r: i
^; 9lrfBcJ ^! boe *!
'ncl?; noi.*; ;
agaaol] a38aoi i
RlBOl
i i -cfjja aisol
.8 . 23.3 ' 20.31 lioa
i t
SSS.3 ^2.^ 13. SI
i
a. 85 e.i^
0.8* 0.23
8S . 02.2 -2V.
. M.2
t ! *
9/:d Jot.* -woila 3.?
JXJta 19*113!! .3iW ao isivasd lerictai 919 ff 29520! ttoi*fllo.oi9q
.alioe
lo d-nsacyom -fxalllqao a,/3 aoqi;
lo -rsmtfxatf oilt no J-nasnaqab ai *effleyoi^;^i-i'lqo T i"^ ao
-X3 931.3! B o^ ooWalooiaq lc ' 9^.1 3ii*%el oo.t oe ,ltoe
lo ai^xscf ^xtt ^oc
e wolrf nc fltoWi.
80
of as much as twelve feet of depth of water in twenty-
four hours. On the other hand it has been found that in
the case of a well dug in heavy clay in the Sacramento
Valley, the water had not yet percolated twelve inches
laterally in a week's time. The general rates of perco-
lation to be expected in depth- of water in foot per
twenty-f our hours {Mm/fay}
Ledium heavy soils 1 foot
Clay loams 2 feet
Loam 3 "
Sandy soils 5 "
With light soils it is difficult to cover the surface suf-
ficiently quickly so that no part will absorb more than
can be retained; with heavy soils the difficulty is to se-
cure full absorption of the water to the required depth.
It follows therefore that where for instance for
alfalfa on a sandy loam the best practice would require
four to seven and one-half inches irrigations (assuming a
maximum beneficial seasonal use of thirty inches), it
would be best to apply eight to three and three- fourths ir-
rigations in the case of sandy soil and clay soils, --in the
first case to prevent deep percolation loss, in the second
Jool 1 silos ^vs9x;
lye soeliua odd" TOVCO ot tfljcroJtllI& 2!
fi.t eioin fHcecfs 11/w d'lf on if s rid"
BS O - ! t; X Y"^
.riitqssb ks-Yhjpot etitf o.t ti'd-sw 9& lo /
iol ^onJSJartJt lo'i
81
to secure full absorption. The most common method of ap-
: j. .:r 1;- etui be
plying the water to the land is by spreading it over a
slightly sloping surface. Under such conditions the dis-
tribution of the water should theoretically, be somewhat
'--s'l '- - -'-'-. /-. r
as shown in Figure XII.
lie area Hfi C D, Hi D.
The depth of initial absorption efba represents
the minimum depth of irrigation with which the land can be
covered under any conditions. As the water travels over
the check, the depth of absorption from the flowing stream
will be proportional to the time during which each part of
the check is covered, being greatest at the upper end, as
shown by fgb gb being somewhat concave upward as the water
will travel more rapidly at the upper end. When the water
'- ' * -" T .- > ft 01X^3 '. v ch
has reached the lower end or often somewhat before it has
reached the end, the supply is shut off. For a short period
all of the area would be covered and absorption takes place
uniformly over the whole check- as shown by chcb. Gradually
however the upper end will become unwatered and the water on
the check will recede toward the lower end, the absorption
being greatest at the lower end where the water remains the
longest as represented by hdc. The total depth at the top of
the check will hence be eh and will necessarily be a function
of the length of the check or ea. If therefore it should oc-
. 2 od
:lq
it
.1 noiJq r ioacfs lc rfd'aab a$d t^.
:h smlJ- 3ilJ ocl- Xjsnoid- scJ I-
cf cf3--
as . 3 1 o. '~v.' D-. ." '-
, wruj c 19V9W64
; jiosifo
sir e j^3'd-B r r-
; 0."---'
82
cur that at the head of the check water is lost by deep
percolation, this can be considerably diminished by divid-
ing the check into a number of subsections, obtaining a dis-
tribution as on Figure XIII. The dotted lines shows the
distribution with an undivided check. The saving in water
is therefore represented by the area HHu Dn D t Hi D.
Don. H. Bark has conducted extended experiments
illustrating these relations.
An experiment was conducted on a strip of clover
45.9 feet wide and 2559 feet long. The strip was divided
into seven equal divisions 337 feet long and a head of ap-
proximately three cusecs was turned into the upper end of
the strip. The head was held constant and the length of
time that was required for the water to advance across each
successive division as the stream advanced down the border
check was noted. The results in Table XXIII were obtained.
lad- aw iosifo siIJ Ic >,- Ed 1
-bivib ^cf bs
s sn.Zni^cfo .anoid-osadwa lo isdinun JB o^nl iloerfo arid
iti'grxlv^a axiT .:ioe.iip bebivlfjru; m iictiw noicfjjcJind'slb
.a iH i G lid it HH .usi'fi sxld- Y'^ becf-xi9a9--;q3 c i s-iolgiarid- a I
^iisxg bsbne^xe bgd-owbnco a^rf ^icfl .H .noQ
levoio To q.Md-3 s nc bgloiibnoo ew toafitiiaqxe nA
saw Gi'i.ta iol J-sal Q3S2 bna gblw sal 6.5
-qjs lo basxl B biu ^nol j-oel VSS. anol^lvll) Isx/pa nsvsa
'lo bne igqqy 9j&t ojr.i bgfr^wd" saw aosejjo agifld-
9fid- >ise. drted-anoo blaxl ajsvy b^sn arfT .qiida 9iid-
aaoioa oo
-icd 0rid nwob bsonsvbe msa'id-a arfd" au noialvib sviaaaoous
iad-tf 9 r i9^ I1IXX 9ldJ3T ni ad
85
TABI XXII I
Division
number
Length
of run
feet
Irrigated
area
acres
-
Time required
~r~
Acre 'Average
feet 'depth
Applied 'in feet
Hours
Minutes
1
537
.38
1
7
i
.28 ' .73
i
1--2
674
.77
2
30
.63 ' .82
1--3
1011
1.15
4
00
1.01 ' .88
1
1--4
1348
1.55
5
40
1.43 ' .93
i
1--5
1685
.
1.92
8
25
2.12 ' 1.11
t
1--6
2022
2.30
11
30
2.90 ' 1.26
i
1--7
2559
2.68 ' 15
i
40
3.95 ' 1.47
i
The Table shows clearly that the amount of water that is
required for the irrigation of gravelly soils increases
greatly with the distance over which the water is flood-
ed. Had this strip been divided into seven sections by
the construction of six cross ditches, the time required
would have been only seven times as long as that required
by the first strip, or only seven hours and forty-nine
minutes, as compared to the fifteen hours and forty min-
utes that were required. Also an average depth of applica-
tion of only .733 feet would have been required as against
the 1.47 feet which were required when it was flooded the
.
'
'
5V. ' '
1
I r 8 .
i
i
23.
t
OS *
.v .
78
|
!
i
. J
t
oo ;
A
f.
.-
l
.
.1 '
f
'
&
1
1
1
II.
2 '
22 '
i
1 SJG.l
i ' '
X
. '. '
'
OS '
11 ' OS.S
3
i
i
1
1
i
. .5
0* '
31 ' 86.2
. t
1
t
i
3 ^ lo ^nircrts sxf;
assssiortl alio^ -^IlavBis lo ncl-
-booll el ne^ew srf* lioli^w isvo s--
qaolooei: nsvo3 o^nl fesbivID rrescT c.
bs^iiupsi srai.i sriJ t aQrfocH) aaoio xla lo
b';li/p9'i d-axid- afi anol as a: ;?v9a ",
snlct-YJiol bnfl 8'iiKjii nsvse Tjlno ic
-nJ - brt aiwcrl n-a&d 1 '!!'! :-
-BO.' i sni;ivV;i ru3 oalA . '
!!
ft; fHHM r.BH
HBBBBBBBBBBBBB* *BBBBr 'iBBB
:. r
IRWI
I7JI
IE:
M IB BBVBI
| BKBBBBtBBBBBBH|
IflBBBBBBBBBBB
IBVBBBBBBMBI
BBBBBBBBBBflrjBBBBBBJ
IBBBBBBB*
IBBBBBB^B
BBBBB'JMBBBBBBBBBl
BBBBBBBIBV. BBBBBrBBBBBBBBBBfll
IBBBBBP. BBBBB
IBBBBr'^kBBBBB
.
::'
entire length of the 2359 foot border. A total saving
of fifty percent in the time water used would have re-
''AC'ce i'^et of 'Correspond in-
sulted. The results emphasize the fact that the econom-
ical irrigation of especially porous soils can only be
effected by flooding comparatively short distances at a
time.
The effect of varying the size of head was in-
vestigated by the United States Reclamation Service in
1910 and 1911. The curves in Figure XIV show the rela-
tion between the number of acre feet on the tract and '
the duration of the irrigation, which depends on the head
of water used.
Table XXIV has been compiled for Kingsbury Tract
No. 8, assuming various times in which the irrigation was
.;.? a tei o-jt.k of 1 rr '.: I c-n "savr:- UM- acr nd
to take place.
lo
.Iiei arrs 0X61
ii sricf lo ncld;xiijyi>
^iL-o r a?iiJi 10^ b-jllqnoo nostf a^xf YIXX. sl.dxsT
ficitv^.I'nj: Si-J xioiil.f xii ascili si/oi-iuv 3xlKC/ee
85
TABLE
Time
Acre feet of
water registered
i
Corresponding
head in cusecs
i
5
2.60
6.25
8
5.70
5.60
10
16
k
4.0
< '; V- 0' *
4.5
4.8
3.02
20
4.7
2.85
60
5.9
1.17
The results show that decreasing the size of irrigation
head, causes a proportionately larger increase in the time
necessary to obtain a complete irrigation, and therefore
requires a greater depth of irrigation water per acre and
a greater loss by deep percolation.
The degree to which these principles have been
adopted in practice is shown to some extent by the follow-
ing. Usually checks vary from three hundred thirty to
thirteen hundred twenty feet in length, six hundred sixty
being typical for medium soils. The width of the check is
adjusted to the soil, slope and size of irrigating head.
The r.idths vary from thirty to one hundred feet for differ
??
ent slopes and sizes of head, the ~ .arrow er checks being
... -AT
3S.9
ce.2
OS. 3
ov.s
a.*
0.^
1
SO o
s.>
1
38. S
1
I
VI. 1
1 e.s
I
3 '
oi ;
OS ]
: r ^ !
lo 9iis adj :^ftiaR9ip9o d-sdtf v/oda ad'J
oionl iQ^ial ^IsdBfio.t^icqo'iq s aa
Dd-slqraoo s rtlsd-cfo oJ
ii io dd-qeb r iacTB9iS
^loo c i?5C! Q'psb "^cf seol
sv ^d sslqi3ni':c: =>?.->: '.3 rioia- oct 991^
idd- ^cf d-nsd-xs s^oa o*. m/oiis el eoid-osi
oct vd-tid* beifjiijjd astr.'* cio'tl ^TSV a^osdo ^IXsoaiJ
ni ctos'i ^*naw
* lo l*ftiw :1
l.soiq^
86
used on steeper slopes with smaller head. Checks 66 x
660 contain one acre and are typical of the practice under
conditions suited to border irrigation. The size of the
stream varies from about .02 to .15 cusec per foot width
of check or from two to ten cusecs,--the most usual condi-
tions being .08 to .10 cusec per foot width of check. The
slopes to which this method is best adapted varies from two
inches to one foot per hundred feet, slopes of four to six
inches being the most usual.
In furrow irrigation it is difficult to obtain
a uniform application throughout the length of the furrow.
The best method to obtain a fairly uniform distribution is
to either reduce the total length of the furrow, or to in-
crease the length of the furrov/s in the lower portions of
the fields by zigzagging them in orchards or building small
basins for ponding purposes. The size of the furrows can be
adjusted to the slope and head in each furrow, in light
soils using as large furrov/s and heads as will not cause
erosion; on heavy soils, smaller and longer furrov/s with
corresponding longer "sets" should be used.
The lateral percolation in furrov/s has been ex-
tensively studied by Dr. Loughridge. The water applied moves
not only vertically downward, but in every direction from the
q M '.1 aoq 08C
* >o asia s& . s^s asoWi
'-xeq OWW5I. o*. SO.**** ntc-il
^1 -10 :.o 3 ;;o lo
io rlw.cl -isq oa^o 01. od 80. yilsd
v baqb ^^ Bl boxtt^ alrict dblxiw o^ aaqoia
xle 07 iflol lc aeqcl , ^ lio^ual ^isq oo sno o^ S8:ioni
ra srl* gnletl
nl
^ 10
-io ^ S nal ^ ^
^ib ; ' , nl^do o^ borf^^aed siIT
so^Doi isil^o o*
Ilena anlfcIJtd tc a
cf *o awo-ri^ lc 3sla adl .asaoq^q Sfiibncq ,ol
IIlw 'SB afc9.i bns awoii^l 93
;-:3 no-scf asil avwii.ul ni
Arfn 3
ballqg* ISJBW sai .3
^ibnoqe 01100
o^ o*.
87
wetted furrow. The downward movement, aided by gravity,
will be the most rapid, diminishing as it becomes more and
more horizontal. This is very clearly brought out by the
experiments of Dr. Loughridge and McLaughlin, quoted pre-
viously.
TABLE
Water removed from tanks 'by days expressed in
percentages of amount in thirty days.
Days
1
Decomposed
light san-
dy soil
20
Loam
31
, ., f ,.
' Heavy
' clay
loam
i
Sand and
gravel
wash
70
Heavy
lava
ash
90
1
17
22
i
' 26
t
18
17
3
30
36
1 42
i
30
29
5
38
42
' 51
i
36
37
10
53
58
1 67
52
53
t
15
67
70
' 78
i
64
67
20
81
81
1 86
79
81
30
100
100
1 100
i
100
100
Table XXV shows the great uae of water during the
first days of the experiment. In all cases more than one-
half the total quantity of water used in thirty days was
used in the first ten days or one- third of the time. The
(
i be
ssstqx 3Y*& ^c: a^iti^d- mo'il &
. e^B*? ^'tirfct ni
;s
1 levaia' ^slo '
1 lias* 1 col
I r-i ri
VI
Si ' 82 ' 22
i
es
. os ; SA ; os
vs
i ' * j&
Ox* ^ '
t i
S3
1 se ve so
i t
Vo
1 j>a sv ov
13
QV as ' is
1 (
001
1 001 001 \ '.- 001
1 1
3
.
'
,.'/.'
j .-: .'
88
lighter the soil the smaller the relative percentage of
water used during the first days, and the heavier the soil
the greater the relative use of water during the first few
days.
Figure XV from the experiments of LicLaughlin
shows thattiae heavier the soil the less extended will be the
wetted area with the lapse of time. Therefore, a light soil
will "sub" much farther in a horizontal direction than a
heavy soil.
The law of lateral distribution of the moisture is
in general of the same nature as for downward movement i. e.
the water will tend to distribute itself inversely with the
distance of the soil particle from the source of supply.
;ST: 9Q.3
eitf iftoil VX
n grit tf arid-
i a nl isea-ial iiO"ra "cfwa !J II iw
.1103 1JVB3.
"ic wsl sdT
SB SI^SJH si,-^ a arf* 'lc laiauss ni
bnsd- lllw is
Iloa sxio r io eo
89
TABLE
Distribution of moisture in horizontal flumes
Light sandy
soil
Loam 'Heavy clay
'loam
Heavy lava ash
Dis-
tance
Inches
Average
percent
of
moisture
Dis-
trict
Average 'Dis-
'trict
i
Average
Dis-
trict
Average
3
f ~
24.38
f*
9
22.85 3
44.58
5
31.07
9
20.85
22
23.10 ' 12
43.61
9
28.85
i
21
20.81
34
21.25 ' 34
40.49 18
27.21
45
18.22
52
19.50
30
39.43 30
26.40
69
16.70
64
15.85
33
[
36 . 33 42
25.57
81
14.24
' 54
25.47
i;
ti
i
93 "
14.18
' 72
20.49
1
105
12.36
'. ' 84
22.57
i
111
10.54
1 96
19.20
u
i
117 ' 7.56
i
i
i:- ' i
Observations on medium heavy soils in the Sunny-
side project indicate that by six days after irrigation the
moisture will be relatively uniform across furrow spacings
as wide as six feet where water had run in the furrows for
twenty-four hours. It was also found that fairly uniform
moisture distribution was secured within forty- eight hours
after irrigation with twelve hour sets on four feet furrow
spacings. With sandy soils without heavy subsoils where the
.1 a 9*3
itfaloH! lo noi^wdxitfa.a
-
naoJ T ^brisa drlgiJ.
i
, ^ !r - T .
.
>3*- av^ i -J^, J^Jyq' 9 iJ.
i ' ^ '
1 lo 1 asrionl
, !
i i giinJ-elog
" f ' ' "\ -
.,.___. -T
VO.XS 3 [ 85. * 5 |
23. 22 6 SS.^S
i
38. 85 ' S.S^
OX.oS; ' 22 38.02 | G
. vs -,' ! Q o^ ' ^s '
o2.!2 ' *S : IS. 02 ' 12
- i " * A . 1 , !
i
r.-> i -.g ' Si..GG ' OS '
03.91 ' 23 ' 2S.8X '
T !
Vo. ! ' 2 ' oS.So ' GS '
1 !
ee.SX ! 4-S ' 07. OX ' 63
i
. _ 1 1 I
i
1 iv>c ' a II 1
i
fa*'. OS ' 2V !
' ' GI.-M ' S8
i
.
OS.2X ' 30X
V3 . 22 ; 8
i
i
,
Ni.OX ' XXX
uS.tX ov;
I ' * _
i
05. V
; 1
J i
HX BXioi
rcic'ilni/ -^Iiiul Jsii* bra/ol o&Is ii
<jjc>ri .Wgie-Y*^^ 'itriiJtw I>ewo8 ac
"'- ' oi no a^as t-' '* fldl
90
furrow spacing exceeded three feet heavy downward move-
ments occurred before the moisture met laterally between
furrows with heavy subsoils at depths of from four feet.
Pour feet spacing of furrows gave good results. The trend
of practice is in favour of a smaller number of furrows of
greater depth, in which small streams of water are permitted
to run fifty to seventy hours. This increase in the "sets"
has not increased the total quantity applied in any one
season for there has been a corresponding decrease in the
number of irrigations. This method not only reduces the
amount of moisture lost through evaporation by upward capil-
lary movement, but also distributes the water in the subsoil
more evenly and produces a greater sideway absorption. It
also tends to produce a deeper root system in the crops.
The size of head or the flow turned into each fur-
row should be adjusted to the soil, slope and length of run
--as pointed out previously. The best results are secured
by using larger heads until the stream has worked through to
near the end of the furrow and then reducing the amount in
order to prevent excessive waste.
The size of the stream used In each furrow is most
conveniently expressed by giving the number of furrows which
would be set with a flow of one cusec. On heavy soils one
rn-YoiJ t viMi osal e jnirf i,ai> 3 9O*a 3h.t
'XXa*i9osX d-sra OTirtBioK slid" 910 lad ba'ii^ooo
yl rnoil lo axid-qeo d-B aXioad..
lo awciiirt: lo iedi-,tuit -islloma a lo wcv^i n ai eo^
miq sis 'is^^v/ lo ai^e^le Ilmua do I AT nl .d*qeo
! ' 3 *9s" 9drf rti safis'ionx aiJT .a-iucr: ^inovau o,t ^11
3iio ' '
odct nx
oil* 2
nl :)3i
J arui'
-Xlqso bisvrqjr ^d n
loocf^ siW al ^*av .o
cfi .noWqioads ^
.aqb'io 9i -i mscfa^a Jooi
-ir'l iio29 oJni bsm^d woll sri
mi- lo rU3^sI bn^
e iio3
d~aoX a'iwd'aJ'.om lo o.
.1,3 j.ac tonsmevon.
B aaojJbo'ic i*ns X-^^^v 3
isb B sojjboiq od 1 sbn9J caXo
bBQil lo 9Sl3 9dT
o:r bsd-uxribfi 9C i bXwcria v/o r i
srlT .TgXatfoIve^i/ d^jjo bs^nioq ao--
r T rjrf-f rfrj' f" 1 9 ^ r t O ">' 3*',Ci ntSSld^B 9liJ Xi'Tilj-' 3'E>XJCi- '- ""-^ X> u
ni ctnwoKto 9fi^. ^niowbst na/f*. bxis -woiiiA ' ed*'' lo bn;
evxasscxs *-KDV9 r iq od-
:Ja SJEtd" lo ss.ta 9ffT
LmY a'aroiTirl lc i 2rlo" T^nxvis b9JG9-:ciX9 Y P 9
i woitt/i rioes ni
Q blwow.
91
hundred to one hundred fifty furrows per cusec are often
used. On the heaviest types which absorb water slowly,
two hundred furrows per cusec are not unusual and on
steep slopes this may reach five hundred in extreme cases.
On sandy soil the head used per furrow is generally l/ioo
Where the slope is flat larger heads are preferable,
1/60 cusec being an average.
Surface Waste. This loss is largely dependent on
the skill and care taken in the preparation of the land for
irrigation and in the application of the water. The run
off collects in hollows or cuts channels to connect it with
the larger bodies of surface water. When water is applied
by the flooding method, it is relatively easy to control
the run- off by building levees around the field-- as in the
Border and Check methods. In such cases the waste should
be negligible in amount. Flooding methods will on an aver-
age give a ten percent waste and furrow irrigation, due to
the greater difficulty in obtaining a uniform distribution,
will generally have a somewhat larger waste. In any case,
the run-off water should be carefully and skilfully used on
lower fields. The problem is one which must be solved on
its merits on each individual farm. No general rules can
be laid down for using the run-off, as necessarily this use
etfo uq awoiiirl ^dlil baribnuri ano od" bsibru/rf
svr d-'ioads rielxlw aoq^d craolvssil sild x$0 .bsai;
no bus XawaucuJ don 913 osawo iiq awoiml b9 r tbm;ri owd
n
avll roflex
ol 190 bsaw 6as:i_ ^i Iloa
;h:ll ai oqols
no *eii9q8l> ^1981-^1 ai a
iol bn^X sii^ lc noWaieqs ic a.: nl n?^j O'IBO brw lliila arid"
.i9d-3
d-os:-noo od .ji onnoiio atuo 10 awoXXoii nl E^osIIoo llo
al isd-flvr riari.? .i9*fiw ooBl-i.ua lo aslbcd 1331 oX sitt
od '^aso ^XsvWaXsi al 31 t boxi*s:s gnibooXl 3a" ^d'
9itf rxi BB~5X9n 9^^ bfOfoi/i assvsl gitibXlud X^ He -run
bXi/oi-ia sctajBw.Siid- asaao aowc nl .sboil
-isvB iiiJ no jiiv,' eborid-sm ^ixbooXfi ,.;tiuoaia n eXdlglXaen 9-J
od- ajoi) .aoWasli'J'J: woiii* 1 ! bns 9cJ-SJ3w dnsoisq nsJ- s 9vl3 333
,Hoi*.wdIiJalI) raio^lfliJ a gnlnlsddo r;x ^Xuol"il.t5 .19-0913
t es0 Y ^ -siaaw lagi^X iariwge^os a averf ^llBiinss -
no bsajj ^iii/iiiaia 5a ^XXi/A9ieo 3d bXuorla isd'sw llo-nui sad-
no bsvXoa 9d *auffi_doliff ano al BXdoiq 9ifi .abXsil iswol
TJ_>~ ^aryri ij3i3n9H oil
92
will depend largely on the layout of the individual farms.
Table XXVII shows the average waste from fields at Billings,
Montana, for different crops and soils in percent of total
water received.
TABLE XXVII
Average waste from fields under different crops at
Billings, Montana. ( Harding )/2/J
Crop
Heavy Soil
I i
Medium Soil 'Ligh Soil ' All Soils
No. of 'Mean
obser- 'per-
va ti ore' cent -
'age
'of
'waste
i
No. of 'Mean 'No. of
obser- 'per- 'obser-
vations'cent- 'vations
'age
'of
'waste '
t
Mean
per-
cent-
age
of
waste
II o. of r Mean
obser- 'per-
vatione'cent-
'age
'of
'waste
i
Alfalfa
Grain
Cultivated
Crop
56 ' 19
* \
15 ' 15
i
13 i 20
t
78
36
20
i
4.5 ' 20
!
5.5 ' 11
i
i
.6 ' 6
t
5.7
14.3
9.2
i
154 ' 10
i
62 '9.4
i
!
39 '8. 5
Mean for
all
.
i
i
84 18.5
134
!
J
4.5 ' 37
t
9.0
i
i
255 '9.7
i
. llIJ
Iscto;
no yLaaizI. bnoqsu III*
B sMsi'l noil 9^ saw 93313 vs orfcJ aworla IIVXX
staaoisq. nl alioa brtB aqoio tasisllib 10 1
IIVXX
cfs accio driSisTlilb
ablsil moil aisaw
.. ,--* .- - '-: -*,. 1
-r^-j ' fff, f^ 1 lice. r.u/i>8fcl
--!-- "^
lioc croiO
-.oil 1 nflM|lo .0'^ rt,39- t lo ,,oi : ;
-^neo'snoid-Bv 1 -cfaso'ancid-.sv' -^nso'aioloBv
lo i .ip 'i
3daBW ocrasv,' SJas
: ' '
nsasl' ic.oll v
13 fl "i'
ctrioo ctici'JijV
' , ! 1
IO
1
SCfSBW
,
- i AO i r \ ! QV ! .D i i gg airl-slXA
01 31 ! ^.^ o* ,
i . ' ! j ^
k S 1 So ' S.-M' 11 ' S.S ' 55 '
i i i ; j
e .s; es ' &, : > ; a. ; oa ; 02 j si ; " - *o
, , ! ! i i ' ' io1 asaM
'j 1 r * IT' ' V ! \S" r ' f> ft f ' -!^i ' LS.&
V.6 y-* . v ^ , * , ^ ^'0* , ,
93
CHAPTER VII
THE FERTILITY OP THE SOIL *
It is often taken for granted that irrigated
lands do not require any artificial fertilizer because of
the fact that the water itself furnishes the required
fertility. While a good irrigation system does have great
advantages and while the silty waters used in irrigation
frequently carry valuable fertilizing material (See Table
XXVIII), dependence for maintaining and increasing the fer-
tility of arid lands cannot be placed wholly upon the ap-
plied irrigation water.
TABLE XXVIII
Showing the amount of fertilizing silts in various rivers
of the U.S.A. (Etcheverry)
River
'Pounds of Pot-
ash per acre
foot of water
Pounds of Phos-
phoric acid per
acre foot of
water
Pounds of Nitro-
gen per acre
foot of water
Rio Grande
Salt River
Colorado
River
325.5
265,
16.34--444.60
31.4
10.5
2.26 43.56
24.4
9
1.03--69.7
I1V /ii
Jios
YTLHTHSS: SET
r xci
lo se-aeoscf r iesill;t'i3l
-s grief aaj-i^
avsri asc.b nsd-3'is n
ai fjo
nectio si tfl
eii^pe-i ctcm o>
-qs
noqw ^liorf?/ >90iilq sc
'ri oc a sii^lV .^J
^ctlle siid" sli^w arus
r io'l
abnsi
t (IIIVXX
lo
IIIVXX
>i auoi r fav rxi a^Iis gnisilx
.A. 2.0 9iut 10
lo
oittfi srl*
-o';
_ T _
1 ajjfijjo'i ' -aorf'i Ic sbiiijoi
isq n' T3a fjioa ol'ioilq
10 d-OOl' "lo J-QOl 3--I0.8
-loi lo abrtwoi
3-10.3 isq riss
iscfflv/ lo ctool
TM
8 5 . OX
i
-SO.f ' Ar>.^.A__AQ Q
s.ass
s^iasiO oiH
lavifi ctlaS
94
Even in Egypt, where the Kile sediment has a high fertil-
izing capacity, it lias been found that manure and artifi-
cial fertilizers should be used. Sir William Willcocks
in his "Egyptian Irrigation" says 4-)
"It would be a healthy innovation, indeed,
if the provision of suitable manures were
to be considered as an essential part of
the project for providing perennial irri-
gation. The day is not distant, I believe,
when governments which provide irrigation
works will also provide manures, and sell
the water and manures together, one being
as essential as the other. I know well,
from observation, that a well manured field
needs only half the water that a poorly
manured field does; and in years of drought
and scarcity manures almost take the plsce
of irrigation. Why should there not be a
manure rate as well as a water rate?"
Organic matter, especially when it lias been redu-
ced to the form of humus, has a great capillary capacity,
far excelling in this regard the mineral constituents of
the soil. Its porosity affords an enormous internal surface,
\
while its colloids exert an affinity for moisture which
raises its water capacity to a very high degree. Its tenden-
cy to swell on wetting is but a change in condition when ap-
proaching its maximum moisture content. The following data,
taken from Lyon Pippin and Buckman, give an idea of the capil-
lary capacity of the soil organic matter.
ni n*v3
liJ^iB ftn.3 s'lirnam d-B-ckt brtwol nasd as:! d 1 . ^dloaqflo gnlsl
aaioeoIIlW raallliW il3 .beau scf bluorfo artsailW'isl leio
3-33 "noi.l-BSiiil ixaWq^-^a" alii nl
,t-99l>nJt .noi-favor^ii ^dcfljssif JB scf 5Iuo-r ctl"
s^aw as^jt/rtem oicfsctiifu lo nolaivoiq arid
lo d'l/sq Ie-i.Jno2a9 rt.s as fisneblsncd scf od"
laliine'xoq ^rxlclvoiq to'
.tl) .Ion ul
xiolrfw
II 3 j DIIJ: a giJjroiK 9ibl:vc r iq oale IIlw 2ii
eno . r i9...'d i 9od 1 ae^i/iis
\YODi .-lOif-ic 8111 2G
blsll !>0rtJjjctBtr: IIsw a daiid
^1 iooq s dsrict. 'i9j. f . % ,v; arid- ilsd vino
^jfl^i-oif) lo 'six: 9',: rri bun jascri blsll b5 f iUxaK.
90-:Ia sild- aiiBd" ^ccrrtls ca^jmom v^loisoa bna
B sd -ion sister oluorid -jT*J .noWs^liil lo
CJ3 liO'.Y 2-3
-9 2&& tSimttJii- lo KPio'l siiJ od 1
lo slnDi-'^l^anoo Is'isijlci.. odd biegs'i alrlct n jinlllsoxs ^ul
ijja I.-iiriidr.'.! siicftrrons m; cjbicTl^ Y^-soicq ad"! .Ioa arlj-
>
doi^ivf 9t/- f d"aloisi ic'i ^diai'lls JIB tfiaxo .abiol.loo .a^J: aliiiw
ail .ggisab ilgM ^xev J3 oj Y*^ 05 "^ isd-aw aii ^o^i^
v noi ibnoo ni a'snf^io a ctwo" al snid-iow no Ilawa od- ^o
-Ilqao 9d*' lo a&bl W avlg ,nii.r4fojjQ I i' ; i
.i^d-sm oi. 3ii, f
95
Percentage of water
Humous extract from peat 1200
Non-acid extract from peat 645
Vegetable mold 509
' _' '__ Peat 190
Garden loam 7$ humus 96
Illinois prairie soil 57
Field loam 3.4$ humus 52
1 61.0 .
Mountain Valley loam 1.2% humus 47
Even after allowance has been made for an in-
creased hygroscopic coefficient due to an increase in or-
50 63. ! S0._4 9.7 -JL* JLj&ljk*3+
ganic matter, the effect of the latter is very strongly
marked on the capillary capacity of a soil. It is equally
evident that with a well manured soil there will as a con-
: rr.c reculr.fa shavr : ' F^-" 1
sequence be a marked economy in the amount of water used
to procure a reasonable crop.
The experiments at Utah on grain and stover gave
the following result s--an average of six years.
j&vq. raoil tfojBiJX9 awomi/ii
eos Mora
(V irasol
IJtos sitlBiq alonllll
-ul na r io'i 9bsai
c - 9aa9-r.!>ol na ct swb .JnsloiTlsoo
ai i9Jda! sxi^ lo ^oori9 9^ t8;ttBm
no
lo ^loaq*o -
-rxoo a a* ill* 9io,ut lioa b^-mam Ii*w a rWlw Jaile
lo cTnworffi srli ni ^raoncss Jos^a.Tt a scf
.qo-io aXcfanouaet '3 siwooiq od"
' no dscTJ --j 8-ja9fltil9<lX9 9rrr
3'i sotwo.IIol 9-W
96
TABLE
Irri-
gation
ap-
plied
Grain
~.
. Bushel
s per A
~T '
ere Stov
i
i
i
er Tons
per Acre
Inches
No
manure
5 tons
manure
15 Tons
manure
Aver- 'No
age 'manure
i
5 tons
manure
.
15 tons 'Aver-
manure 'age
i
Hone
5
10
20
30
57.9
61.0
59.7
67.6
65.1
73.3
86.1
83.0
87.7
90.4
75.9
91.4
92.5
99.1
95.7
i
67.0' 2.11
79.5' 2.32
i
78.4' 2.55
t
84 . 8 ' 2 . 81
i i
83.1' 2.86
3.25
3.77
3.73
~
4.04
4.19
t
3.92 '3.09
i
4.48 '3.53
4.25 '3.51
i
4.85 '3.90
i
4.77 '3.94
1 63.9
I.
1"
83.8
90.0
79 . 2 ' 2 . 88
i
4.07
t
4.50 '3.81
t
The results show the highest yield of grain with a twenty
inch irrigation duty; more than this quantity of ?<ater de-
creased the yield, and with as much as forty inches of water
there was slightly less grain than with five inches. A some-
what higher yield of stover was obtained with thirty inches
than with twenty inches of water, but the yield was decreased
with forty inches. The average of six years shows that water
applied in excess of twenty inches to corn was not only wasted
but was postively injurious to the yield of grain. The yield
of both grain and stover was decidedly increased by manure,
the stover showing the effect considerably more than the grain-.
"T~
snoA -taq
snoT 'xsvcd'o
i
1
-Ill I
i . .
\
-q*
_
1
b9llq
-19VA 1 3fiOJ 31 BitOd" 5
oVi f -- r iev. r ancT 31 7 anod'
a 9.aonl
SIJJTIBJtV
t i
i i
1
i
r~ ~~l "
i i '
t
1
60
. O vkC O
1 32.
' O.Vc- ' 6.3V
i> STI
VJ . **>
!
6.V3 '
eno a
; |
'
!
3
. ' OZ* .
\ i . O
sc.
'3.9V ' *.I6
1.38
.
0-13 '
3
1
i
1
t
1
T3
.5' 32. &
1 sv.s
33.
2 '.6V ' 3.2G
.<SS
1
Vt 03 1
\ . yc
01
1
1
.S' 38.
1 >0.
16.
s.^8 i.e
7.V3
D.V6 '
02
i
1
1 {
1
i
&
.5' YV .
1 91.
38.
S '1.38 ' V.S8
^.oe
1.58 '
OS
!
i
i t
1
r c
JL*
S! r\~3 A
1 70. *
88.
0.06 3.38
1
C.S6 '
1
i i
-r
!
.:* a rtf^v ni-3-i!i 'ic bisi^
-30
lo
Siiio'a -'-
aeiloni
arW woila aj'lw&oi adT
v,.!nJt ifortl
aasi ;
.
sild" d"wd t'isd'av/ lo asiioni
awoua a'laav xia lo sgJisve sifT .8"
d'on ac irico cd 1 ssiionl vd/ii^./d' lo uasoxa nl
* u _* ---
bi8l^ siLJ od' aiJoliJL'^nl svitaoq as\7
oso a^Jw i3vcd"d tn niJ3^3 rid'od lo
.3 .zUid-'anlwotia ivo
97
The increase was much greater for each ton of manure with
the five ton than with the fifteen ton application.
Most of the soils of the irrigated regions are
deficient on humus and organic matter,, and it should always
be the first object to supply this necessary amount of fer-
tilizer. This is usually done by the growth of alfalfa,
clover, peas or some other legume, turning in the green crop
and thus putting the nitrogenous matter directly into the
ground. It is often desirable and necessary to supplement
this by some form of fertilizer, usually the ordinary stable
or barnyard manure.
If leguminous, it is generally grown as a cover
crop during the non-irrigated months of the year. Much of
the success of this method is dependent on the skilfull
handling of the water supply. During winter months the cover
crop will receive all the necessary water from the rainfall,
but great care must be exercised during the summer months
that the water intended for the main crops is not absorbed by
the cover crop to the detriment of the first. In some lo-
calities an extra amount of water is put on the .land especi-
ally for the cover crop, --being in addition to the required
amount of the main crops. In other districts again, it is
the practice, to apply only sufficient water for the main
crops and to let the cover crops care for themselves. It is
rf*iv; wnflm lo noa dose iol *e*fl9iB down BOT oaaeionl
.nol*sollqqj8 no* neatflil srfd" ii*lw afi* no* avll
anoJb?*-! had-asiTil 3*i* 1 alloe 9ii* to *ioM
a Muoria ^1 bns ,-19.** SKI oinagio bi aj/nunl no
10 Jmroiaa rx^aeodn 3l:W ^Iqqwa ocf ^osLcfo *a-ill
allallfl lo Jiiwoi3 silcr Yd snob ^IlBysw a sirTI .
qo-^o 99t3 dto nl snlq;cu* , 9,-,-iuaeI -leitto s.uoa ^xc aaeq
odnl ^l B-.t a-o-oneo^in sitt snld*i/q euri*
sl-drfa Tt^nlfi'io eu&
sldeiiasb nsJlo al II .6110013
lo nno'i omoa ^d aid*
1 3V oo 3 as
oio
lo rfo-j., -1B3- a:* lc a^nom
Ilulliiie ail* no Ju,.baaqsb al boifjsn alii" la aasoowa
<i9vco sd a;-ncr.i
r; oto Us avlsoe'i Ulw qoio
3iI i
l-^o &9aloi3xs sti ^^r:: 9i*?o *fl9'3 ;
arnca nl .*3<ill 3d* lo *ns;nl-i*3D sri* o* qo'io ad*
*q al ia*svs lo jiUJOfftB Bijxo nxj 801*11*0
ao.l T lfc&c nl 3filsd-- t qoio .levco ad* 'icl
rn 3d* io
c*
98
only by experience that one can obtain the best practice
--each district having its own individual merits.
The amount of organic matter can be greatly in-
creased by always ploughing in the stubble of the previous
crop. On no account should it be burnt. By burning all
the nitrogen is taken away by oxidation and only ash left.
A thorough rotation of crops also greatly helps
in retaining the amount of organic matter. Experimenting
in Oregon Professor W. L. Powers states that "It is probable
that the water requirement may be decreased one- third where
a good crop rotation is practiced. "
ic. cJasd ari* n.U;tcfo oao enc tad* sousl'isqxs -fcf
.astern Xejj&iviinJt nfo .eJJt 3 aiv.ail cfolidsik ,1
-ai Tgld-fiS'-is 9cJ HBO isJctani olaag'io lo
Jjoyq sd^ lo slo'cfucts 9ilc ; - nJt s
Ha gaimwd ^Q .dT^;d 3d ii blworia Jnyooo.s on nG .c
.dial XI'BJS ^Ino 6'rua noJWsbixo vd ^ws no2,8* ai ns
aq.Csii -;Id-J3ei5 oel.'s aqoia. lo noWjMtorc ifeuoio:- 1 -'.
o Ic *nuoi-.w sxi^ sninlcdsi nl
si il" *a*^ asJ.srJs a^s^o-l .1 . ictiesloTi nogs-iO nl
ni ctnaffioiii/pai i9*BW sri; cfaiid
ca^q al nol^scfcg: qcio 60. ps
99
CHAPTER VIII
THE CROP
In one of the previous chapters it was stated
that under ideal conditions, irrigation should take place
when the soil moisture has reached a point somewhat above
the wilting- coefficient, and that the frequency of appli-
cation would be dependent on the time taken by the soil to
"dry up" after the application of water to the next stage
just above the wilting point. This applies, of course, on-
ly theoretically. In practice it is necessary to take into
consideration, in addition to the above, the effect of such
waterings on the crop itself, at the particular period at
which the water is applied. It is not so much the case of
obtaining, by irrigation, a maximum sjnount of dry matter per
cusec of water applied, but rather a maximum yield of the
useful part of the crop. It is hence of importance to know
in what way the general growth of the plant is affected by
a variable application of v/ater.
Assimilation and other processes favouring plant
growth are especially rapid after an irrigation, gradually
diminishing in intensity and almost ceasing before the next
irrigation.
In the Utah experiments it was found that during
n: . --J-
10HO 3HT
BJBW tfl Bietfqsiio ai/olvsiq sild- lo scto rtl
lo 'iOflbtfpsi^ 9ild-.*ai D .
ao
S^Y; 'lo
:LBd e.;txl,sr;> cfnsbnsqsft sc! fjlwcir noicfso
w-woo lo t 3
* ."
odnl. SJiarf cd- ^3aa&03n al dU solJo^q nl' .^IIsoWs^
rioua'io oell ari. -svods ad.t ' od npJtdloDa nl
' ' " no
lo 38-GO siid- dowci oa c^n
laJda.-n '^b 10 Jnwont:
arlcr Ic M&l-j i^'lx^i B i9fsi ducf" Vbsllqqe I^^BW' lo oeawo
won:! ^ 9ori*ioqn.I lo sousii si cfl .qo^o siW lo
al dnclq 9i-J. lo ^v;qi 3 B9ja Uw nl
.i^w lo noi?J3olIqqB slcfaiiav s
i3ild:c
p. ._ a f*
JIG -
100
the first week after the irrigation of peas, more than
five hundred pounds of dry matter were added to the weight,
and of oats, more than seven hundred pounds of dry matter
were added to the acre.
The vigour and general condition of the plant de-
pends largely upon the development of a good, deep root
system. In the early stages of growth, the plant uses most
of the materials gathered from the air and soil for the de-
velopment of its root system. When these are well develop-
ed, carbon assimilation by the leaves is hastened and the
growth is increased rapidly. Later in the life of the
plant, the root growth becomes less, and the energies of the
plant are more largely directed to the development of the
parts above ground. When at last the sterns are well develop-
ed and a sufficient quantity of material has been .stored in
the various plant organs the growth diminishes, first flowers
and then seeds being developed. It is important, therefore,
that as early as possible the root system be made large and
well developed. To obtain this condition it is essential to
keep the soil moderately wet in early spring. In districts
retentive
where the winter rainfall is large, deep/soils will usually
have sufficient water for the initial root development and
no irrigation need be applied. If however the climate con-
ditions are such that at seeding time the soil is not well
tf eiora ,aseq lo
slid 1 o* bsbbe
-if) Ib afomroq
ini 9tt idd-ls aioaw d-aill grid-
m ^if> 10 aoruroq bsibn^ii
itevga rtaifd- s-iom t cd-so lo
.9102 Sn':"
lo noWJtLnoo
cssb ,Loo?, fi lo
aa^0 d-fljaXq 9l* ircis l
sricf lo'i Hod i)hfl IXB 9.ad- uio'il bensxafls alBli9*Bm arid- lo
tsw sic 939:.* -ns^W .rn9d-a^3 Jobi 3*1 lo d-nsmqolsv
dd- ncq.u
fil abnsq
ai
grid- lc sill arid- r:J I?*-
lc s&ls'iang etl* Sn , .aaeJ aaaocscf
sitf lo d-nomqol9vsb 9ild- od- osd-oe-rlfi
. i
cclovsfc II 9w 91 B sms-j-a eild 1 d-asl * ns ,
d-uoi siid- ,*nslq
sic;:: sir. d"nelq
-I 3.,oda
'i t s.3ritiJ:nlmx.o rid-woin sxj armgio driBlq a:/clii:v arid-
.d-nj3d"ic; k .-.i ai JI .isqoisvai; snlsd a.Bssa nerld- bns
*rf ~,i=d-?vs jcoi sxi* aldlaaoq aa vll* 2^ --^d-
ill^ Jeje.' -' - "
.in9.ias ai *1 nold-lbnod Blffd- nlad-dc cT .Beqolovsf) Ilavr
I
d-aib al ' .^niiqa \Iiae nl d-'sw ^Id-i9bom iioa srld- q
'-f r r fW aansl a^ II'lnls-r iOvi.;.cv.' 51^ 9i9- r lw
OJtt
^'a sis
101
is not well filled with water, thorough irrigation immedi-
ately before or after planting is essential to a proper
root development. The part of the plant above ground is al-
so definitely affected by the quantity of water applied.
As the water applied to the soil increases, the plant be-
comes longer. With a lack of water the plant remains short.
Not only the stalks but also the proportion of leaves is
distinctly affected by the amount of irrigation water applied.
In a grain crop the value of the straw is small in
comparison with that of the seed. Hence as much of the plant
as possible should be converted at harvest time into seed.
On the other hand when a crop is grown for forage it is de-
sirable to secure the largest proportions of leaves. The
following extracts from various reports and papers fairly es-
tablishes the practices governing these basic principles of
plant growth.
Alfalfa. "Where the winter and spring pre-
cipitation is sufficient, or where winter
irrigation has been practiced, soils which
have good soil moisture retentive power need
no irrigation before seeding the first crop,
which in most localities generally occurs in
the spring months after the d&nger of kill-
ing frosts is passed. Porous soils which
have little retentive power for soil moisture
usually require irrigation before seeding.
After seeding the young alfalfa plants should
receive no further irrigation until the plants
show the need for water or even not until they
show signs of suffering for lack of moisture;
this is desirable to develop the root system
ilcflw bellil Haw don si
isqoiq s od- JJal^nSiUS al ?;ni^n'slq iscM:? -10 s^cclaci -
-is ai bflJUOT-p, avodB dri-ilq oJd 1 'lo d^i^q sifj? ,rfr:e;,tqoi9V9f)
.ballqqa iscfsw lo tt'ltxaup srW ^d L'sJoaTia ^lacMnllsb oe
-scf cfnalq oild- (S^aBs-ionl lioa . erW c-i bsilqqs lactsw snct aA
druaiq ed^ r isc}-BW lo ;-lO3l 2 if.j-iW .lesnol aantoo
IJ S ^
i 'lo Jrtuoms 3iJ -jc! b9cios'i r i.j3 ^I
ai wa'icfa srl* lo 9.c/I?.v arid" qo-io niai^ & nl
nc
fiBlq 9fj "io ilojjn: aa eonoH .bssa srlct lo
.59.33 oo'ni sfi-l-d- uasv: 1 : d..j siisvneo .scf Blwoila siu'laacq as
-si) ai it 3g*iol 'io'i nv/oi3 al qo'. r o a nsrfv;
adT . ssvn^I lo 3ncJ:T r ioqo r ;q J-s^gisI 3uj
as -;i r :i.3l a-';?qsq Lrca c, Jioca-i ajjci r i^v nto .'1 aJ-
lo aslc Ior.i f iq oxasc.' oaeiid gnin'iovoa aeoiaO-Jiq
:-. ,.aiw exit pnorii" .
913- .'.v -iv. .di-sioiilwa ai nol-isjiqio
fcisan 'lowoq gsviin^is'i eij^aloct iioa .1x^05 evsii
oc r io d-erril o/ii sai^Dss d-iclscf asid.c3iiii on
T 1 r^\ r* v*r- e*r~r v r> - 'i of - r*/- * 1-1 - " "
liolrlw alioa sjuoio*i .baaaaq si 1 ;inl
91 llO3 'lol T9WOq ?V ' "j 11 SV6.CI
32 -.sd-'iA
:.n t->v
;n srlj
2 .artgia
102
downward instead of confining it to the
surface, as may occur with too early ir-
rigation. The root system can be fur-
ther strengthened by cutting the young
alfalfa when eight inches high. When the
alfalfa has established a well -developed
root system thecommon practice on reten-
tive soil is to ap ply one irrigation be-
fore or after cutting. On gravelly por-
ous soils and on shallow soils, two or
even tiiree irrigations for each cutting
may be necessary.^/
Cereals. "The soil should contain suf-
ficient moisture at the time of seeding
to germinate the seed and to start the
plants growing. No irrigation before
seeding is required for a retentive soil
when winter precipitation is not too
small, or when the soil moisture has been
supplied by winter irrigation. Irriga-
tion before seeding is necessary for a
soil which is too dry because of defici-
ent winter precipitation or irrigation.
Where irrigation before seeding will keep
the ground wet too long and delay the
seeding, it may be necessary to irrigate
immediately after planting. This prac-
tice is objectionable for soils that have
a tendency to bake; it increases the evapo-
ration loss and requires an earlier second
irrigation.
After the plants have germinated, the first
irrigation should not be applied until the
plants require it, but before the plants be-
gin to suffer for moisture, which for a
moderately retentive soil will be tv/o or
three months after seeding when the plants
shade the ground and have grown to a height
of six to nine inches. A second irrigation
is usually necessary when the heads just
begin to form, and a third irrigation is
often desirable when the heads are filling
out. The practice will vary especially
with the character of the soil and the time
and extent of precipitation; a good reten-
ei:d- o* J-l gnlnllnoo lc bsetfanx crr ;
-itft sd'nso'niad-aie *oorc 9rTi ; '.J :*'&
iisil< . riT ill B9rlonx Jili9 r;
bsqoi'9Vb- 1I9-.7 s 6l3iXda*88- aaii
nc soid-os-iq noffimoogiid
-9d''hc.iJ-*5"". illi WIQ Tu-tq OJ 5 * si i-i ca sv
- r --oc llav/i^' n'C .^rijocf.uo r i3d"i.e r io
: - , aiioa v/cll
o ifoBS "rol anc
-Iwa ni^^rtvO biwoJifi Ilos 0-1T
Ic srf.icJ 9il--- *.s 3i^sior.
a oct bna bssa adi'^i .: r i3S o*
Biolsd aclJB3.Txi o'/i .gniwcia al
lioe 5V.tci-ne75 r i : r id Lj-iJr^pai tl
oo* tfcn 3i nolo l B"lqlo9'iq lo^ni ? nsaw
aari s'irJaio::i Hoi srl* nn'vr ^c ,1.1
iflsimi r i^
'
lo 9s,u.3osd V-t^ oo:J a * iloMw lioa
Jtiii 'io rtcii Iqioaiq
Illr ^nibe-32 9*1 clod noliflgx-rrl 9'i9--',V
-flleb I>ac aaol oo* Jgw broraig sii*
o+ ^-laassosn. 9(5 ^an cfl
iiT J .'snIdTi--.iq 10*!^ ^leJslbanmti
aiioa r iol slcf^ncid-oe'Qo'.o si 90!
s's 3nl *1 { 93ffld ocf ^onsbnsd
ru 2?tiJJp3-i bar sad nci'i
-sd aixiBlq srLi sclscf *urf .*! eii
a ic! ifoirlw t 9i*axom tol is!'..
a^rcla slid" nsd'.? ?vxi&99<3 13^13 a.linofti
B^'od-
'ivtl fcno39a A .as^oci r xia lo
*. 3ild 9ii.? ; - TjII^WSiJ 31
i OT
--r ' -- : -
103
tive deep soil with a moderate winter
and spring precipitation may require
only one late irrigation when the heads
just begin to form; a porous soil may
require four light irrigations."/^
"In a number of irrigation experiments
with grain the best results were obtain-
ed both in quantity and quality of yield
with three irrigations at the jointing,
booting and soft dough periods. At the
jointing the embryo head is forming, at
the booting it is about to emerge and at
the soft dough the kernel is f illing.
"At the Utah Station the growth of wheat
was divided into four stages (1) when
five leaves had developed and the plants
were 6" 8" high (2) the early boot
stages when the plants were just swelling
preparatory to heading (3) the bloom
stage, when most of the plants v/ere in
bloom and (4) when the plants were in the
dough stage. The experiments were con-
ducted on a loam soil. The experiments
were conducted on a loam soil. The pre-
cipitation averaged 17.8 inches and 37.3
bushels per acre wer-e raised without ir-
rigation. The highest yield of wheat was
produced with three irrigations of five
inches each applied at the five leaf, the
early boot and the bloom stages. Irriga-
tion applied after seeding before the
grain was up and that applied after the
dough stage, decreased the yield. Where
only one irrigation was given the best
time to give it was at the five leaf
stage; where two irrigations were used
the five leaf stage and boot stage were
best; where three irrigations, the five
leaf, boot and bloom stages were best."
'
Potatoes. "Retentive soil except for
late planting is usually sufficiently
moist from the winter and spring precipi-
tation to require no irrigation before
-
. ,artWrtlot 9^* * a anolcfr a^Tii aid* a
d-A .a&ol'ie- dw
'*s ,snl.7.icl a I ossrl o^tftro sd ' 3/1 j
d-s bna 9^1 sine od" ctrods 2! *i snl^oocf
al isnioii srict rfai/ob
ilw lo rfctwoi* erW nol^s^a rte^U sri*
rtsriw U) W>i -wol oinl bsbivlfc. saw
q artt bn b?co.^vei !
Soocf ^lijao srfo IS) ^S-^i 3--
lairt 9^3" ; aJnslfl ad;
nicolcr srij- (S) gt iiasi-'O.* i^ o / a ' ia
nx d-iaw a-^nslq sri* lo taotn neaw ,s^e^a
at *^w.e*n*Jq )* nffW{-*) ftoa nwold
Rtt^E^ft>^ ^^ '.IlOB ' SIBOl B HO
-o-ic "adr" ..Iloa m&ol B no 9^cw&
6.t*5*f>ni asrlDnJt-.- 8. VI be^isv^ noilBd
lit *trorf^Jtw beBijri 9--ewWss i-3q al
aaif tfaariv? lo blsl^ Iso^lrJ sriT .noj
evil Ic anblt?giiil sarfiid' rldiw bowbciq
arlj ,lsei wrll ^1 ^ b^ilqqs iffl9 8?noi
-aglTil .333^3 -^ 1 t? " 4
siict en^ls'J -^JLoaa i9*la b&iiqq* 1
lad-la beiiqqa iartt bno qi; a
lalv '
o.r- jaw nclj;'3i':
6V f'l 9:13 is 33W itl C ' ; ^^
~
J ,lJ39
. 2_
js '
104
seeding. Dry soil must be irrigated be-
fore planting. Planting in dry hot soil,
followed immediately by irrigation is not
desirable. Daring the first stages of
growth throughout cultivation is more im-
portant than irrigation, and no irrigation
may be necessary until July. Too early ir-
rigation after planting may compact and
bake the soil around the roots. Potato
vines are shallow rooted and frequent irri-
gations, especially early in the season
when the water is cold, will retard the
growth; for this reason some irrigators
prefer to apply the water at night, when
the soil and water have had all day to warm
up in the sun. The moisture in the soil
should be kept fairly uniform until the tu-
bers begin to form, when a heavier irriga-
tion is generally required. The soil should
not be allowed to harden around the roots.
The last irrigation should be applied before
the growth of the tuber ceases, in order to
give about 1&--2 months for ripening in dry
earth. The number of irrigations will vary
from two to four for sandy loam and from
four to six light irrigations for a porous
sandy soil or a shallow soil. The need of
irrigation may be indicated by the appear-
ance of the plants; dark leaves indicate a
lack of moisture, light yellowish green
leaves indicate an excess. An examination
of the soil where the tubers form is an-
other good indication. A sandy soil is in
good condition when a ball of earth squeezed
in the hand will retain its shape.
Cotton. "Soils for cotton should be given
sufficient moisture for germination before
planting. With cultivation no further ir-
rigation should be required for six weeks
to two months. From two to four light irri-
gations are given during the period of plant
growth. Too heavy irrigations at this time
results in excessive vegetative growth at
the expense of crop production. After about
July 1st, the crop on most soils will re-
, r j. OC J j e
* r
3T.J.
-
'
-11 ' .
: -1 ane
3 si LJ- nl ^I-xjse t^i*
hDt Iliw t biOO;..M **.*
y: i. -
IlOB
-r- r, jr[ 9V^ri 13^B
Ci &isj*sioK srH .nua .add 1 nl
-rid 1 sri* iiiriu .-incline; ^Itisl i^^-i s-cf bl;
^ - M 'art 1 i noicJ'
biWGirS Ij-Oti Sill ,^9'"iWp3'T \. 4--
.a*oo^ s* bni/ciB n8
9-iolecf boiicce ad bloods r.eiJ -L -
"
a
-,c-i -ri
viAv Il^'.v aoi*aslJt lo i3d:f
on- Ttfiof i,bnaa io'i iifol o*. owd" ffioit
awo^oq a io r i ancl*33xiix ^rfgxl xxa od-
lo D93JK adT .xioa wcILeria lioe
^JSS^JJ^SSTt-hSyTeSiJ
. . < _
nssia dfilwoIII : v ai Jalom ic
iiafliijujr.s riA .USQOXS B soifini av~
-ns si mol j'-iscf.od- 9dff siSiJ /
ai Hoe ^hfisa A .ccoi-J coxSruL uc 19J
1
n owd od 1
d-fi
0:
e
10'5
quire irrigations at ten to fifteen days
intervals. While some wilting in the
early season may not be harmful, at the
flowering period moisture should be
maintained so that no wilting will occur.
One or two irrigations after the first
picking are usual . n
Orchards. Deciduous trees are deep rooted when
the soil conditions are favourable; they require less water
than other irrigated crops and for that reason the need for
irrigation is not so apparent. Citrus trees are not as deep
rooted as deciduous trees; they are evergreen and therefore
the evaporation from their leaves is continuous and the max-
imum moisture need for fruit growth is in the fall; for these
reasons citrus trees require more irrigation than deciduous
trees.
Pall and winter irrigation is very advantageous
in the maintenance of orchards, where the greater part of
the rainfall does not occur in these periods. As a general
rule trees must not be irrigated, or very cautiously, when
they are in bloom, for such early irrigation is said to in-
terfere with the setting of the fruit.
"Orchard soils should not be allowed to
dry out too much for an excessive dry-
ness in early or middle summer will in-
jure the tree for the whole season. On
the other hand, over- irrigation tends to
decrease fruit production and delay the
ripening . Y&
i owe? 'io
" .ler/a.u SIB gniilolq
w aaa 3'
xol boen-artf
i ct :;
o-:
aq to bs^aai-iii tsrii;
oa $
ai no
b-13 awowxiWi:-0 ai aevesl
noljaioqavs
-ni oct
i -'V ax no I" ifi'iti- *r sdrii .<; c*n^3 IIsU
-.r.r n.'' -1JJ.OG ^OXI 1 2'0b ilBlillBI .3ilj
v . J W i^.V^
;3.id 9G d'Ofl 'JflSSJTii aSSMC
9ri* io s ' rf^i'.-r
>jjjorfs ai. 'otO"
106
The last irrigation is given in the first week of September,
so that the new wood may have a chance to mature before any
freezing occurs. This late irrigation also has the advan-
tage of keeping the leaves somewhat longer on the trees,
aiding thereby the formation of the new wood.
Young trees should not be irrigated .more than
once or twice a season. This is essential to the formation
of a deep drought resisting root system. Professor Wickson
draws the following conclusions:
"For deciduous fruit trees on deep soils,
fairly retentive, ten inches of irrigation
water, applied at the proper time, during
five months of growth and fruiting, accom-
panied by good cultivation, is sufficient,
even when the rainfall is only about
enough to prevent drying out during the
winter.
For citrus trees twenty inches of irriga-
tion water is usually sufficient where the
rainfall is considerable and for the more
retentive soils, ten inches applied at the
right time may be adequate."
A diversification of the irrigated crops will usu-
ally result in an increased duty. The reasonable water re-
quirement should not be based on the needs of the crop of
maximum water requirement but rather on the average water re-
quirement for the entire ares, --the average being of course
proportional to the areas which each type of crop occupies.
By diversifying his. crops the farmer's need for water will be
Jo aaw d-aill nl nevJig - '
; o* c-
* aal* a0i*-*ii*l **! sMJ? ,?ue?
- - r-.^
.>oow wan ad* lo K - - fl
310..1 be*3i'n. scf *on bluoiia aas^* gm/oY
aJtJ-aiffxcl ad* c* Icl*rtaaae a I airCP .ncasss B goiw* 10 aono
.alioa qs-3i> no easid- cJ-li/il airofrbios
z: :ii lo aerlonl
' . . ' .
lo
o-'icrfs en* ^ol brua si'"'
arid- *.3 b9ilqq a arise Jt ns* ,sj.ioa
3jjp3&j8 d
lilw aqoio be^agliii 9*W xo nclJaoll
i 'istfiw sldBKoaae'i sill .^*ufe &*a9-ic
lo qo'io Sii* lo ab^sn erfcf no baaad :
r j?ctBf srssisvs stW ac
I
ar
^1
III
":
iiniinn
'. ; '.
, v '- '' : '
107
more uniform and constant, instead of the greatest need
for water falling within a comparatively short period.
The same applies to an entire irrigation project, helping
materially in the proper distribution of water by rotation.
The greater the diversification of the crop the more uni-
form will be the required capacity of the main canal.
i. x : --T,' if k->tc*-tl-<U
If a majority of the acreage of any project is
planted to one particular crop, say alfalfa, it is impos-
sible to serve adequately all of the land in that crop at
the time of greatest demand, unless the canal has been de-
signed with a large excess capacity for that particular pur-
pose. Most of the other crops such as grains, potatoes,
corn, beans, cotton, etc., have a lower water requirement
and their maximum demands do not extend over as long an in-
terval of time as that of alfalfa or are not of the same
magnitude. The results from the Cache Valley experiments
illustrate this very clearly. (See Figure) In fact some of
the crops of low water requirement such as fall planted
grains, early potatoes, strawberries, etc., may be cared for
entirely before the time of peak load. Other crops of low
total water requirement, but which may require water during
the peak of the season, are corn, beans, sorghums, etc. Po-
tatoes and sugar beets may require as much water as alfalfa
jllttSJ 9
.ii ailta* flB od- asllqqs irEE
J *tI6 taoi erf* nl -?IIlid*fli
lo o'jwsi miol
lo Us -^Is^ajjpsfcB sviaa oct oldia
anso aiirf aislro; '.bnBKSl) rf a ad- 0913 Ho sfiilcr aiW
aaaoxs 'syisl s xlctlw
a^ ^o^- aqoio lorid-o srict to ^aoM ,.aoq
^wol a sviiii t.od-f^ ,nodd-oo . a.osscf t rnoo
aol s^ lave bnsd-xo Jon o& abruajaei) mwml3tm ilarfJ baa
jriJ Ir- J-QU e-se ic B'iisliB lo d-ajd- a^ ami* lo Ifiv-'isJ
r io-^xe ; i9ilsV silosQ stfo mpil a.lx/aai
Jo^l nl V 3 r i^3^ sea.) .-ci'i-'-alo \-csv a
I Hal ao rlotia jj 5 .lupai' isctaw woX 'lo aq.o r io 3iict
... . - - -
s.
108
during the two months of the peak loads, but on a given
farm are not likely to require service at the same time.
In crop selection and carefully planned crop ro-
tation may be found one of the most practical means of re-
ducing the peak load of an irrigation system and maintaining
a generally high water duty. If this peak can be distributed
through the season, it will result in a lower construction
cost, and in many economies in operation and maintenance.
jq srj
.
brtis nolJ^osUea qcio
JB me-arja noWaglnii xi^ lo baol ^asq srtt .^ni
nso aUsq uirf^ 11 .^Jub is*ow rl^Irl TjIlBiane^ a
-isvrel u ni ^Iwaan 11 1W *1 ,noaBS3 add dg
m nl bru
109
CHAPTER IX
YIELD OP VARIOUS CROPS UNDER VARYING
AMOUNTS OF IRRIGATION APPLICATIONS
Under the direction of Dr. Harris of Utah a very
complete set of experiments has been conducted to determine
the effect of varying quantities of water on the crop yield.
The experiments were conducted in Cache Valley, Utah, and
extend over a period of some fourteen to seventeen years,
hilst of course these results are ^strictly only of practic-
al benefit to the area concerned, it nevertheless gives an
accurate reflection of conditions under which a maximum of
various crops may be obtained. The results obtained are re-
produced below, together with results obtained from various
other sources.
Irregularities in yield are often traceable to
the fact that the complete series were not run through all
the years. It must, therefore, be kept in mind that exact
yields cannot be given too much weight. It will be much sa-
fer to take the results as a whole rather than any one fig-
ure or point on the curves. In the case of the Utah curves
the actual average yield for the different irrigations are
shown by the dotted lines, while the heavy line represents a
medium yield obtained by considering the average of the great-
. jlrfAV "50 CLI2
j liedU lo ax-naB . ivl lo' ncxdos-rlf) add 1
3r;x,.:'isd9 od fcatfojjfcfloo rxoocf e.sxi. BctirarclisqKa lo dsa sdslqmoo
.M9X7 oio srld no 'isdsw lo asididnawp 3ni^iB'v lo
i/ol &;noa lo boiisc a . iav
fj* 3^^ ad-iwasi
ns asylg aaalsif^isvsn -t beui&oaoo aaiB siiJ oJ ^ilanscf Is
lo mjjtilxjs.-n B rlolrlw xofim/ anoirHLrtoo lo nol*09il9 r i
-91 yin )9flc^C0 3-U39-'I 3f .>3fi 9Cf
i-o^l bsuls^dc "aJli/asi ilctlv isiid-dgod 1 .wolstf
si a'^soB'id- nsd-lc -5^.3 blaxY nx
iiguoi/a- xxirt don sta'v 20x192 gdelqntoo sd* dsrid /Ofll
*".'.
d-iwid bnim rtl dqsx 9d ,9-iol9'i9iid t d;affl
a -lou.i ad IlJtw dl .drfgisw rlom:; ood nevig ecf donrtco
B3 iid al .aavi. - 7 no crnloq 19
9llx5 siSd 1 i i- 1 egsieva I^tfd.oa rid
J7af -
110
er number of tests to be nearer to the true average than the
average of a fewer number and weighing accordingly. A one
year test is not given the same weight in arriving at a
point for the heavy curve to pass through as a test covering
several years.
The following table shows the average of a total
of one hundred seventy-six trials extending through fourteen
years.
vnfAv <=tfr:t Piftt OJ I
-.J 3J-4W V*
9no A . ' ^OOB ;-. ' uoe i
d-e sniviiiB 01 .trig; rtsvis ^on e'
"oo dasJ B afi rl0oiil* 3aaq oct avii'.o '^v^s. . dfij a
. ' 39^ 1
jcf B'lo a^jsisvs sd* ewoxla sicfjsj gnlwollol
Yi rl3woia^ gni&nsd-xs alali* xla-^nsvea I>9ibrLri
Ill
The Utah results are tabulated in Table XXX
and illustrated in Figure XVII.
Alfalfa (Lucerne J
Acre inches
water
Number of
trials
Number of
years
Yield in tons
per acre
,.
14
r
ij LW }
11
2,655
5
36
7
i
3,233
10
28
-
11
3.923
12.5
3
3
3,783
15
30
14
4,294
20 5
12
-.
12
4.165
22.5
1
1
4.090
25
14
12
,
4.544
30
10
-
10
4.515
32.5
2
4.841
35
3
3
:
4.198
37.5
1
1
4.400
40
4
4
3.740
45
2
2
4.613
50
_
8
,
8
5.355
52.5
2
2
3.718
60
1
1
4.691
65
-i
1
3.399
67.5
1
1
4.230
75
1
1
5.007
90
1
1
1
4.520
97.5
1
1
3.768
;.*
o
ii
6
21
01
o
1
G
03
SI
01
01
2.21
er
02
CO
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112
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to
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ft) p,
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CD
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ca
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co
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rf*.
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CD
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CO
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w
CD CO
to
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to
-3
CD
CO
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00
o
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w
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00
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co
01
01
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ro
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ct"*3 P P *O ^
O CD e+ O CD P
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1
to
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to
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o
to
-3
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01.
to
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H
CD
w
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ro
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P *Cfl QJ O O
O 0) l Htj O
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& CD cH-*C( ch
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to
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to
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to
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to
ro
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Average
profit
3
CO
c+
on
P
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c+
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P
ct
P
<
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4
CD
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113
In the Modesto Turlock district investigations
were conducted during the years 1916, 1917 and 1918. The
results are shown in the following Table.
TABLE XXXII/?3,/
Check No.
1916
1917
1918
Amount
Total
'Amount
Total
Amount 'Total
of water
applied
inches
yield
tons per
acre
of water
applied
inches
yield
tons per
acre
of wa-
ter ap-
plied
inches
yield
tons
per
acre
1
50.04
7.68
--
-
41.86
6.64
2
56.05
8.74
68.44
6.75
55.01
5.06
5
22.06
8.01
29.42
6.92
45.44
6.17
4
17.21
7.91
*
21.59
6.94
18.45
6.41
5
25.25
8.91
29.75
6.96
58.71
6.58
/
22.59
8.75
55.12
7.09
28.11
6.75
7
29.41
9.52
44.42
7.00
47.75
6.45
8
28.95
9.56
45.64
7.64
56.99
6.65
9
26.72
8.9
47.77
4.25
. .
41.95
5.71
In Oregon--at Corvallis similar experiments were
conducted for the purpose "of determining the value of irri-
gation for increasing and insuring productiveness of the
agricultural lands in the semi-humid Willamette Valley."
f od-aefioM $d$
ni nworia
oiei viex
.,-oIbi .OH >iO
1 1
"too" ~IatfoT|
''Ttw&J?~ * m70 ??!
Moiif ~ ai * ^ c >IexY ( .i
SiBW lO bi9I : i' "ISJflW iO^
^ j ' C- J3 '"1 9 cf
bs ii'^cjB 1 1 ?c Quoct bsilqcjB
xc ! e-io.a'
1 1
1 1.1 1
__ - T
T " T "
1
5.6 ' 36.1 '
85. V O.OS
r t
i i
eo.s ev.e
.jo- ' n"<- ^ i rTi"" ! Q
i
vi. D ' *.c ' se.c
1 !
2-^.K' 10.: dO.22 ' S
, i
rjL a I g&.SI ! ^9.0 '
63. IS ' I6.V IS. VI '
! 1
ae.e v.ss ! se.a
3V. 62 52. e,2.
3V . 5 &0 .
i ?
2i.se. ' c;v.s se.s->
i
o>.3 ' 6V.V>> ' 00. V '
t '
. i i
so. a | ee.ee ^a.v ;
o.e^ ' ae.e se.ss j a
IV. S ' 56. I* 53.
vv.v^ ' e.e ' 2v. 32 : e
i i <
cvioO d-B--noBSi'- r:I
^o' 1 e srftf icl bsoo.obnoo
aricf lo caorrsviJoi-'bo'io >^ni r ix'2nl bn? gr^EBsioni 'to'l nolctiig
*.TrrreV ft;'- : ' J ' sr'J -x' ibnnl
114
The following Table shows the results on Alfalfa
TABLE XXXIII ////
Year and Treatment
Total
yield
in tons
per
acre
A.
Value of harrowing and irrigating for
B.
new seeding
1911 (seeded 1909 without irrigation)
1911 (seeded 1909 with irrigation harrowed)
1911 (seeded 1909 with irrigation unharrowed)
1912 (seeded 1909 without irrigation)
1912 (seeded 1909 with irrigation harrowed)
1912 (seeded 1909 with irrigation unharrowed)
Irrigation before and after cutting
2.17
4.16
4.08
4.00
5.42
4.10
G.
1911 6" before cutting
1911 6" after cutting
1912 2 irrigations of 5" before cutting
1912 2 irrigations of 5" after cutting
Furrows versus flooding
4.41
4.59
10.37
10.30
D.
1912 one 5" irrigation with furrows
1912 one 5" irrigation with furrows
Amount of irrigation
6.37
5.17
1911 2 irrigations of 4", total 8"
1911 3 irrigations of 4", total 12"
1912 2 irrigations of 4", total 8"
1912 2 irrigations of 6", total 12"
1915 (seeded 1909 without irrigation)
1913 1 irrigation of 4", total 4"
1913 1 irrigation of 6", total 6"
1913 2 irrigations of 4", total 8"
4.51
5.22
6.70
7.75
2.15
3.80
4.22
4.22
Alfalfa was weighed as green feed in 1912 and as cured hay
in 1911 and 1913.
-. r .cr m'i
'
nJ: 1
t
__a
OS. 01 '
liJ - . -S-3Li 7 .? '*
it
r o ' i inoJtissJtTii Jwjia-Jtv QO^l bs&ssa; 1181
rot-jt Tliii utlw kOUl nsfises; life!
i'f ', oWsil-iil ciJiv; eO'21 ^slbose) 1161
' , ^ oidJ8^i?i *uc-rttl ^061 osJb^ea) SI81
' . !
I*.*
95 * Id
3iv*l 2
3 ' "awo'iiwl il^iv; no
rid 1* noJtfasM^ "5 eno 2JI.
"^ lo sfiottu-'itiJt 2 J
S'f . si IQJ* -'^ lo BfioWiglTil "W
SJ'^ i '8 I^Jdoi , ;i ^ lo snciri^gl^ti 2 SIS!
t Is^od- t "0 lo anoWasliti 2 2161
lK>.T33.JT*-t d
' ; . "^"lad'j*: t 11 *
'
; "8 Isdo^ t rt ^ r io a.'.. .Mil 2 S
a* Bs.i-j.fsv/ asw a
.S13I bns 1181 nl
115
The experiments conducted at Idaho during 1910
1914 give the following summarized results.
TABLE
'Class of
'soil
i i
Average depth
of water ap-
plied in feet
Average yield
in tons per
acre
i
'Clay loam
'areas
i
'Areas making
'maximum
'yield in eact
'experiment
I
2 . 40
."
2.73
i
4.91
5.47
An examination of the results for alfalfa shows
that this crop can profitably use much larger quantities of
water than most other crops grown under irrigation. There
is a decline in yield after a certain maximum amount of wa-
ter is applied, but the decline is slow. Alfalfa is seen to
i-
be much less sensitive to over irrigation than potatoes and
cereals. The Utah results show a maximum yield with fifty
acre inches, although twenty- five inches gave very nearly
the same amount i. e. a saving of fifty percent of water
gave only a 15.2 percent decrease in crop yield.
In the case of the Davis experiments at the end of
the six year experimental period, the stand on the areas
given the heaviest irrigations was only 27 percent of the
original stand, the excess use having enabled grass to come
0161 sniiwb oiifibl *fl
e
J ftnod ni' -qs <SD*SVI lp f liosj
1
18.* 0.2
i
; I
I
' u r 39 Kl biSi'^' (
i . VA a - ' sv . S *jaaail*i*qxe
! I '
lf ^ ad-lwse-i 9i. : lc no
lo
rtsrf*
-3W Ic *rtr;cina munilXBfit nxsjtso n 19*1^ blsJtY cl enllo^fa- a si
* nssa al BllBll. .woJla si sniloab 5>r< *w<J ..ballqaa ai
s.90*s-ro&. nsr:^ acl.-rorsl'iii n-svc cJ sviJlanse aa^i dofffii ec'
lo *n90 r i;?q ^*'lilL "io gr.iv^s s .9 . j.
.blsi 1 " qoio nl ssBgioafc dnsoisq S.SI vino
asy-iB axi* no ins* a ail* ,.boiisq Is*npmiioc-xe ir.s^ xia arfo
s r{7 -'TLgq V2 "^ino SBV? aaoi^s^i'^'xi jaoivsaxf and' n9vi
sax; aa6o:;o 9il* bfLS*a
116
into the alfalfa. The best stands at the end v/ere areas
given thirty to thirty- six inches of water, --which is un-
doubtedly the most desirable quantity for the irrigation
of alfalfa under general Sacramento Valley and San Joaquin
Valley conditions.
In 1918 the best yield at Modesto was with a to-
tal depth of 28.11 inches.
In Oregon Professor Powers conies to the follow-
ing conclusion, "The maximum yield of alfalfa in all trials
has been secured in the dry seasons with ten or twelve in-
ches of water, but in wet seasons with six inches of water.
The most economical increase in yield with irrigation has
been secured with four to six inches of water."
Potatoes. Table XXXV and Figure XVIII show the
Utah results for this crop. Although considerable variation
is noted in the trials during the different years (the ex-
periments extended through fourteen years and the Table shows
the average of two hundred sixteen trials), the general ten-
dencies are distinct. The most favourable amount of water for
potatoes seems to be between thirty and forty inches. For
applications above sixty inches the yield drops very rapidly.
This is probably due in part to the fact that excessive water
prevents the tubers from securing the supply of air needed
for optimum growth.
a.-.:
al ox-aV-- t i9d-J3-7 lo &9doni xla- J otf :viq
nc/ ' craom srIJ-
oL XLO fens ^II^V odrtsrr, Bile.
.. ' 3l
a rttlw' a6v/ od-ae.bo,,l d-s blsiij cfaacf odd- SI
.39.iionl II. 8S lo dd-qsb
f ^ cwf aemoo siawoi toaesloT-I n:"
lalij ll ni-*'ilj3ii.3 lo >isiY niwr.ixBnt 9dT M ,, ! orxoo gni
-nl 9 r /l9i-?J- rep nad- xl^iw snots.a9a ^b aii^ nl >9i^oa ctsecJ .
'!d-fiw lo as^orl xid rfd-iiT anoaaea J-gw nl d'jycf ttod-flw lo L
asd ricld-JB^i'iii rfdl.v blai^ nJ s^es'-ionl iaoirrionoos .
".-jsd'aw lo aarioni xls od- ixrol riai-sr 01.
9xiJ^ 'Toria IIIVX 9'ijjni r i bxue VX>-JC alcIoT
iJ-sx^ay si fJaie bianco fin-fJcildlA .q<yio alrJ-t
-21/50^ d-rroi3'ilJ-> aad 1 ^rslij/ft aljBxid- arid- nl . el
da aidrt-T 9-fd- 5nu ai.^s^ nascHx'ol .ri^oi^d- osbne
-J! acid- tislsiid 1 nssd-xla ba'i^ri^ri ow.
lo 0-ruj-o.Tts elcfjeiwcvsl d-aorn srfi 1 . . . :. r is a:
b LlexY -'
.-scf:.;d- a;
mmmmmmm
mmmmmm
mr.nmmmm
vzmmmmm
mmmmmmm
B
I
var/ot/s
-V
117
TABLE XXXV faj
Acre inches
applied
'No. of
'trials
No. of
years
'Yield in bushels
per acre
None
12
12
117.37
2.5
4
4
157.19
5.0 -- J
. .
39
14
162.23
7.5
20
9
165.38
10
12.5
39
4
14
r W I
4
217.24
284 . 87
15
39
14
228.62
17.5
1
1
1 293.75
20
13
13
266.53
22.5
2
2
2 321.18
25
4
4
204.02
27.5
2
2
345.50
30
7
7
269.92 *
52.5
4
4
377.59
40
-
2
. 2
341.44
45
8
8
271.39
50
1
1
83.45
55
3
3
240.00
60
fi ?
^
304 . 00
65
1
1
246.00
67.5
1
1
245.00
75
1
1
149.00
82.5
97.5
2
1
2
1
149.00
85.00
9
SI
ee.ivs s
0.3
OS
G.V
01
t 1
3 . 21
95 ' '.
!
ol
1 ' !
c.?I
SI
02
t '
i r> I
i t
5.22
i i
32
i y I
i r
03
110
The Oregon results are as follows:
TABLE XXXVI/'//
Year and Treatment
Yield in
bushels
per acre
1911--a
dry season
Dry
135.1
3 irr
igations of
1" * \
250.9
1
ii it
3"
176.4
2
ti ti
2|f"
240.7
i
1
n ii
5"
190.9
5
ti ti
2 "
254.9
2
it n
3"
258.1
2
n
3"
308.5
3
n n
3"
292.5
1913--wet season
Dry
109.8
1 Irrigation of 2
n
172.2
1
ii n 5
ii
213.3
2
n n 2
n
145.2
The average results with potatoes at Gooding,
Idaho, for the four years, 1910--1914 are in Table XXXVII
39
Hi fclelY 1 d"n
i
i.sex '
srnosai'J?
briw issY
a
5P J8--1ISI
^u
8.052 '
"I 1
o.aaoWaaJt'rtl 5-
^ r |
it V ''
i
7.0i>9 '
i
"Is "
11
o
"5 "
it
e.^cs '
1
11 o "
S
as '
"S
2
5. 60S
"S '
ii o
3.2G2
"S
. 3
i
' 3.QOI '
,a03J833 J-9W _5I_^I.
n on ; '
M
>o rvn ? -f nvi Nw ^
. ;is S
t! i- i!
!( 2
9'i*
119
TABLE XXXVI I //J
1
No. of irriga-
tions
r
Total water
applied in
feet
Yield tons
per acre
2 1
.69 -
3.2
4
1.72
6.75
6
2.85
6.7
In Oregon the maximum yield for the wet season
was with three inches of water, while in the dry season it
was with six inches of water. The most economical yield of
potatoes obtained in the course of the experiments was se-
cured with the aid of three one inch irrigations, applied
ten days apart, giving a yield of 58.6 bushels per acre
inch .
In Idaho, the conclusion was reached that it
would not be advisable or profitable to apply more than two
to two and one-half acre feet per acre on clay loam soils.
Cereals. Experiments at Utah on corn were conduct-
ed through a period of seventeen years with the following re-
sults, given in Table XXXVIII and Figure XIX.
laiBfi l^'JcT 1 -B'^iTix lo . oM*
aiioici'
. t
t
"J "C j
s.e
-=Y
93. ' S
! '
57 . S
2V. i
1
! v,o
t
58.2 .3 |
noassa *9ff ' ofiUt tci bi9i-\ r ftiumlxjim ad* 'ttojasiO nl
noaaaa ^i& edi al sii-.w t -i9^ew' lo es^Dfti 99-tu* fWi.T saw
fc'slY iBolaionoos cfaom onT .rcsd-cw v io- asrioni xie fit iff aaw
sijistixs o.-'i lo Scisi/oo 9iJ nl benia^do
MB . ; j.fQ^- ae'i -* lo bi QiiJ
iU---'
3i9flai/d 6.3S io blsl^
-sa aew
.rloni
acls.nlonoo sxii ,OrlBbI ftl
si^w moo no
d-nasiiisq>:H
lo >oJt
be
?io
120
TABLE
Acre
inches
applied
f No . of
trials
ft'o . of
years
'Yield in bu-
shels per
acre
Hone
13
13
57.33
5
13
13
61.39
7.5
8
8
79.14
10
17
17
77.23
15
8
8
93.93
20
17
17
81.80
25
8
8
99.16
30
17
17
81.49
40
, 9
9
65.30
55
8
8
'
96.78
On the San Joaquin and King's River Canal system
the follov/ing results were obtained.
TABLE XXXIX
fear
' Depth
plied
of water ap-
in feet J
1907
2.13
'1908
1.65
1911
1.38
Aver
age
1.72
V3
SI
i
GS.
16 '
i
SI
SI |
*I.
,ev '
8
i
S2.
,vv '
VI
VI |
se
.5* ;
g
O
08
.18 '
VI |
V X
i
1
61
.69 '
8
8
i
l
i
6
.16
VI '
VI '
OS
.56 '
6
8V
.36
8
8
JBO
a^n
bna
.b^ila fdo 6Tew
i
X -40 -48 $6 6+ 72
*mm
m
m
:i
*+ ** ft '*
: jv ;
; ''"'''
121
The Utah results on wheat, extending through a
period of thirteen years are given in Table XL and Figure
XX.
Acre
inches
applied
No. of
trials
r
'Ho. of
years
i
Yield per acre
Grain 'Straw
bushels' pounds
None
9
9
"i
38.37' 3982
i
5
34
13
38.23 ' 3540
i
7.5
18
9
41.54' 3301
i
10
38
13
42.90' 4142
i
15
34
13
47.10 '-4796
i
20
4 -J
- 4
45.70 ' 5940
i
22.5
4
4
, ',
44.60 ' 6757
1
25
18
9
46.46 ' 4311
t i
35
18
9
48.55' 4755
i
45
4
4
45.80 ' 6250
i
50
18
9
49.38 ' 5332
t
67.5
4
4
43.50 ' 5794
i
boxieq
.XX.
'*3,I* '
i
l OS.2i> '
i i
N '
Si
51
? r
e
Si
8S
SI
si
51
02
Srk *T
Oi .i
122
The experiments at Gooding, Idaho, gave the follow-
ing results.
TABLE XLI
No. of ir-
rigations
Total water
absorbed per
acre foot
per acre
Yield of
grain
bushels
per acre
-
13.3
i
.
.36
23.3
3
.75
28.7
4
1.23
31.8
6
1.76
33.1
8
2.27
36.0
9
2.94
27.5
t
Results on wheat experiments at Davis, California,
during 1912-1914 gave the following:
r
. Jl ! !!.
i
- r _
'"- - Pi
- i *
'"Isd'BW XjSd'oS -TEX 'lO .O*I
t
7. w . ~, ^
ceq Sacfioa-cfB 1 ' anoWagii
.
i
3. [9
i* 1
d-ool sio.3 1
t
f
__ -
^iO^JS^
!
s.
^ r i
v>i-
i
i
J
i
*
s.
(52 !
as. i
i
!
!
.
.
S2
:
uV .
6.
i
v c> r ' ' k
Oi J.
r
!
1
1
.
So '
8T.i . a
1
.
ee
vs.s s
i
.
V2 ;
^\i' . 2 ' S
!
1
.
* r .-r c , alvBu d-s a^ne;iti'X3UX6 .issiiw no
123
TABLE XLII
No. of ir-
rigations
Depth ap-
plied
Yield ir
ger a
L pounds
ere
1
inches
Hay
Grain
--
2703
657
1
6.0
t
4267
1157
2
10.1
6100
1529
2
15.5
5050
1029
Typical practice is represented by Table XLIII
which shows the net duty on grain in the San Joaquin Valley
TABLE XLIII
Year 'Depth
applied ft.
i
1907 '
.74
i
1908 '
.84
i
1911 '
.96
i
1915 '
1.11
i
Average
.91 ft
At Utah, oats gave the following results for a
period of six years- -Table XLIV and Figure XXI.
1
1
OB"
JbJ-alY -q -ioc.9u. -TJ
lo .oM
t
riJ
1 asiioni 1
~~~i
! "~
i i
1
?5o
oOVS ' '
I !
!
van '
r-t rvO K I
\ oaJ/ u o
i
1
!
i
1
S23I '
0015 1. 01 '
s
1
i
; J
'
201 '
3.31 '
2
9ic : s r i vci bodnaas-i^s-j: a
r .il bBsL...^
1
i
1
- -
" T~ ~~l
Y.
VOb'.I '
i
i
^8.
1 8061 '
t
' '
i ^Q
1 nei !
1
i i
1 1.1
1 <SlSl '
i
j-l IS . 03B1-3VA
z ic'l j^Iwas,''! 'ir;J:vToIlo j. Si-'J ovs^ ac
^.^sx brt^
VIJX slds ; r--ai^9 xia lo
124
TABLE
r
r~
Acre
No. of
i
No. of
. -
Yield per acre
inches
trials
i
years
applied
'
Grain in
Straw in
i
bushels
pounds
i
None
6
i
6
50.57
1876
t
<
5
. 21
i
6 ,.
57.51
2077
B
i
' J
10 r
18
i
6
60,18
2107
i
15
18
i
6
72.82
2563
i
20
6
t
6
74.40
2725
\
50
C! 3
\
3
79.90
2774
i
45
6
i
76.68
3149
i
On the whole it will be seen th- t the yield of
cereals is not nearly so much affected by irrigation as is
the case with potatoes and alfalfa. In the case of the
Utah experiments on wheat, for instance, fifteen inches of
water gave almost as high a yield as any treatment and yet
the yield kept up fairly well with the very heavy irriga-
tions. It will be noted that where no irrigation water was
applied the yield of wheat were fairly satisfactory. There-
fore, in practice, it is doubtful whether more than fifteen
inches of water would pay for the extra yield obtained.
Oats is a plant which is more sensitive to mois-
ture than wheat. In the Utah results, there is a gradual
VL1X -JL1
: r~
~r~
1c old ' lo .otf ' 9ioA
---'
r
- :,i i i i ~T*i
i r "i3xlqCB
al vrs-ictc. nx rtxfli-^
1
8V'8X ' V5.05 '
i i
3 onoVI
j t
IS. 75
i i
5 xS ^'
t i
VOX 2 8X40 B
3 ' 31 01
i
^PQ ' QO QV '
O G i* _A O -* 1
\ \
3 81 ' 31
r I
32VS Oi.^V
S ' 02
! I
\ rtr>o ' OP ^V
-^| ^ ^i W ^* w 1
S ' 5 ' OS
: i
QMS O.^V
3 Si-
i
. -- j _._ .
clef ttssa 3d II lw J'i slou'v 9,tl nO
[ x,9Cf03ii^ :Ioum ca ui^an cTcn al SXBSISO
lo saso sitf nl .liflllJ3 Dai: aso^-sctpq ittiw 9a.eo
1c ac^onx r.-srfin.soneiaiil loi. .*^sijw rto s-taeinliscxe
*ns:s*B9i* vn.^ as >ielT a ^^ 2^ Jaoinla svs 3
: w -x*aw .10 Id- 33111! Qn 9-ia.oAV cfBd* becton ad. XIIw cH
' 9ii^
bial 1 ? BI^XD 9*tt_ Wi ^aq biuow is
125
increase in the yield with an increase in water up to
thirty inches, above which the yield decreases slightly.
The yields were not greatly different for quantities of wa-
ter between fifteen and forty- five acre inches.
The results on corn show the highest yield with
twenty-five inches of water, although yields are almost the
same for all quantities of water between fifteen and thirty
inches. While the yields were somewhat reduced by exces-
sively large irrigation applications, this w-.s not nearly
so much the case as with potatoes.
Citrus Fruits. In the State Engineers Report
(California) for 1912- -1914, the following data of the net
duty on citrus fruits to Southern California are given.
'9*sw til 33^9'ioni rta ridiv; b.,3i^ 3ild~ at
.^1 .-Mail a BsajBaiosb D-isl^ 3i# rfoirfw avcdr. t asr:or;i
-aw lo asl^ld-iwwp tol
9V 11 -\cHol bxifi 99J'i.c'i
rfcf iw blelY -ta^risin tW -'foii^ ntoo no siluao-: 9xiT
arl* J-^oiniB SIB a&lai-z r^-jil JI c , r i3*-'w lo 29::oni av ^
^liif* bua nosoili rwewd-su' -13* - *c- aaWi^iiaup ii.-i -101 onaa
n arv 2^^ ,a
as saso 3iIJ iloum oa
r ic fl
i3 9*10 sirrro-iJLBU n-i^i^waJ ataiiwTl a-ui^ic no
TABLE XLV
126
Location and Source of Supply
i
1 Year
i . J
i
i
Acreage
Depth
of wa-
ter
applied
feet
Gage Canal and Riverside
Water Companies
i
i
'1899-1905
i
80,667
2.25
Riverside Water Company
'1901-1908
i
9,000
2.29
Riverside Water Company
'1912
i
31.5
4.10
Riverside Water Company
'1912
i
19
2.58
Santa Ana Valley Canal
'1912
20
1.79
Santa Ana Valley Canal
|1912
18.4
1.52
Del Monte Irrigation Company
'1906
i
2,000
.73
Del Monte Irrigation Company
'1907 :
i
2,000
1.10
Del Monte Irrigation Company
'1908
i
2,000
-
.73
Del Monte Irrigation Company
'1909
i
2,000
; ,.73
Palomares Irrigation Company
'1906
i
600
.71
Palomares Irrigation Company
'1907
i
600
.83
Palomares Irrigation Company
'1908
t
600
.83
Palomares Irrigation Company
'1909 ! ^
i
600
.
.83
.1 rj-OX *'
vlCtqj/ci lo ao'iwoJi bos nol^eooJ
-BTST lo
t '
ball
4
1 '
1 1
.-
~ f 1
i :
eJilsiavlrt bns IBOSO S 3 B3
3S.2
v.oe.os' soux-^si'
1 i
aalxwqmoG ia*aW
es.2
ooo t e 'soei-
Yn':cinoO isJeM sbisisviH
01.
3.15' ' 2JWI 1
TCnaqpioO i^^ifc' sbiai.vLi
85.2
91 21iil '
i
vitsctiitoO i^d'JjW s&isisvi)"!
ev.i
02 ' sjyi 1
i
I anaO ^ailjaV crtfi &$a&
23.1
5V.
^.81 ' -iei*
000,2 | 3061 |
laaaO -^sllBV cnA uctnafi
^nsqmoO noi*3^1iil sinoM IsQ
01.1
5V.
1 000,2 ' VO^'I'
i
' 000,2 ] 3091 1
-^naqmoO nolJs^.tTil a^noM IsQ
YrtsqruoO ncivt^nliil SocioM -IsQ
SV.
000.2 eoai' '
t
^oaqmoO aol^.saiiil 9-tnoM lad
IV.
i
- >~\ r - r\ '. .' r *
OOo cuwx
YT-O'ttoO HOlJSS^' 1 -'- BS'IB'TtOlflu
58.
006 VOt'l 1
, i
VjOi-jqmoO noittsgl'-rij. -io*X3ntol3i
'58.
' 008 S06I'
i i
50 .
OOS ' GO'GI 5
> i
^nBuMoC nol-tjs^lTiI esianiol*?
127
Deciduous Orchards and Vineyards
TABLE XLVI
Location and source of
supply
Year
Acreage
'Depth
applied
feet
r Remarks
Sierra Foothills
South Yuba Water Co.
1909
6,900
2.62
Bear River Canal
1909
5,000
2.62
t
i
Sacramento JValley
!
Palermo Land &
1
Water Co.
1912
33
.75
'Prunes
Palermo Land &
i
Water Co.
1912
10.5
1.64
'Olives
Palermo Land &
t
Water Co.
1912
10
.80
'Olives and
i
'Peaches
t
i
Yolo Water & Power Co.'l913
14.2
2.29
'Prunes
i
i
Orland Project '1914
14.2
.25
'Young Almonds
i
i
San Joaquin Valley
i
Turlock Canal '1909
37.8
.38
'One irrigation
Pumping plants at
t
L.adera '1910
222
.86
'No irrigation
Fresno Canal '1910
160
.49
*0ne irrigation
San Joaquin & Kings '1906
t
River Canal '--07
104
2.64
t
San Joaquin & Kings '1907
t
River Canal ' 08
15
2.38
t
Pumping plants at
i
Friant '1912
20
.83
'Two irrigations
Pumping plants at
i
Friant '1912
150
.06
t
i
i
Southern California
i
Santa Ana Valley
i
Canal '1912
15
4.83
'Walnuts
Santa Ana Valley
i
Canal '1912
t
21
3.18
'Walnuts
t
3i' 10 S3'I.c;C3 .Ofl," -, '
, "
1
ooe t 8' ec . .o:
ooo. a 1 eoer ; u
! (
.
I
59vllO' 8.1 '6.01 '21
A ,
.bfijB as\ ' 08. 01 ' 2XQi : .00
86 "
aafu^ti' t?2.2 2.1-1 ' iiei'.oO t? -L r i :
it i - i
sbnomlA r^ni/oY' 52. ' 2.M ' XC1'
\ i i vrrv rfff-o^
,; 8. ! 8.vs | eoei 1
d~js
38. ' 01
G. 0?)1 ' OIC1'
' 0061'
6.2
: - ' 7061'
85.2 51 '80-- :
! t It
otfT ! 56. 02 ; Siei ;
'80. ' 031 ' 2j
i i ' '
i i '
8 . 31 ' 2J
1
, -,
.
,
128
Carlsbad
Truckee
Carson
North Platte
Minnidoka
South
Minnidoka
North
Boise
Project
Or land
Project
K!
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RETURN CIRCULATION DEPARTMENT
TO- + 202 Mqinjjbrory.
LQANTPERIOD T
3CS^55-aL-!=
FORM NO. DD6,
'UNIVERSITY OF CALIFORNIA, BERKELEY
BERKELEY, CA 94720 ^ ,
U.C. BERKELEY LIBRARIES
NON-CIRCULATING BOOK
UNIVERSITY OF CALIFORNIA LIBRARY