1^1*4,, Division of Agricultural Sciences 
 
 A ' k ** _ 
 
 I \ \! UNIVERSITY OF CALIFORNIA 
 
 ^h6Q — ~ 
 
 CALIFORNIA AGRICULTURAL 
 Experiment Station 
 Extension Service 
 
 CIRCULAR 523 
 
CITRUS planted and irrigated on the contour, Las Posas Orchard, at Somis, California. 
 
 THIS CIRCULAR TELLS 
 
 • how plants, soil, and water depend on each 
 other 
 
 • why contour irrigation is practical, even 
 on steep slopes 
 
 • how to lay out a contour planting, particu- 
 larly one designed for a small acreage. 
 
 THIS CIRCULAR DOES NOT ATTEMPT to fur- 
 nish complete information on laying out 
 contour planting under difficult conditions. 
 University of California Farm Advisors can 
 direct you to a competent engineer for ad- 
 vice on such prohlems. 
 
 AUGUST, 1963 
 
 This publication replaces Circular 440, "Contour Plant- 
 ing and Irrigation on Moderate-to-Steep Slopes," by 
 Lloyd N. Brown, September, 1954. 
 
 A CONTOUR GRADE is the 
 per cent of slope of a contour 
 irrigation furrow. Grades vary, 
 for reasons described in this 
 circular, from V2 foot to 3 feet 
 per 100 feet of length. 
 
 CONTOUR FURROW IRRIGA- 
 TION implies irrigating a crop 
 planted on the contour. There- 
 fore, contour planting is essen- 
 tional to contour irrigation. 
 
 SLOPES discussed in this circu- 
 lar are those too steep to per- 
 mit successful use of ordinary 
 irrigation methods, such as 
 borders, basins, and straight 
 furrows. Such slopes are often 
 called "moderate-to-steep/' 
 
LLOYD N. BROWN 
 
 PLANTING AND 
 
 IRRIGATION 
 ON THE 
 
 CONTOUR 
 
 ENABLES YOU TO 
 
 • use steep slopes otherwise unsuitable for irri- 
 gation — it makes possible the use of steep 
 slopes which could not be irrigated properly 
 with any other method except sprinklers. Ir- 
 rigating on the contour allows water to flow 
 slowly in furrows that cross the slope on 
 gentle grades. 
 
 • avoid serious soil erosion — since the furrow 
 grade is calculated according to the texture 
 of the soil, the danger of furrow erosion is 
 minimized. 
 
 • use irrigation water more efficiently — since 
 irrigation water runs deep on gentle furrow 
 grades, its percolation into the soil is much 
 greater than that of shallower water running 
 in steep, straight furrows. Water use is there- 
 fore more efficient. 
 
 THE AUTHOR: Lloyd N. Brown is Extension Soils 
 Specialist Emeritus, Agricultural Extension Service, 
 Berkeley. 
 
 MOST OF CALIFORNIA^ good flat 
 lands have been put to use. Inten- 
 sive agriculture is now literally 
 "taking to the hills," and contour 
 planting and irrigation are provid- 
 ing an effective way of using this 
 steeper, hilly land. 
 
 Contour planting and irrigation 
 is widely used by southern Califor- 
 nia citrus and avocado growers. 
 Outstanding examples of such 
 plantings can be seen in Ventura 
 County, where the system has long 
 been used by citrus growers. The 
 practice is also employed to a lim- 
 ited extent throughout California 
 by growers of bushberries, decidu- 
 ous fruit, and vegetable crops such 
 as cantaloupes and tomatoes. Prac- 
 tically all strawberries are planted 
 on a slightly modified contour sys- 
 tem. 
 
 Planting and irrigation on the 
 contour grade could be applied 
 profitably to other hilly or sloping 
 areas of California, with almost any 
 kind of crop. 
 
THE FUNDAMENTALS OF IRRIGATION 
 
 Before ATTEMPTING any kind of irriga- 
 tion it is important to know certain fun- 
 damentals. This is particularly true for 
 the difficult practice of irrigating steep 
 slopes. 
 
 WATER IS STORED 
 IN THE SOIL 
 
 Soil acts as a reservoir to store irriga- 
 tion water. Therefore the soil occupied 
 by the plant roots should be filled to field 
 capacity. Plant roots take from one to 
 several weeks to deplete the stored water 
 to the permanent wilting percentage. 
 
 Soils vary greatly in the amount of 
 water they will hold at field capacity. 
 When soil particles are small there are 
 more water-holding surfaces per unit of 
 volume than when the particles are 
 larger. Fine soil will therefore hold more 
 water than coarse. 
 
 For example, loam holds about twice 
 as much water as sand; clay holds about 
 twice as much as loam. If we call the 
 capacity of sand 1, loam will be 2 and 
 clay 4. In terms of weight, sand holds 
 about 7% of its dry weight in water, 
 loam about 14%, and clay about 28%. 
 
 The following are terms frequently 
 used in this circular: 
 
 FIELD CAPACITY: The quantity of wa- 
 ter that soil will hold a day or two after 
 irrigation, when the water has freely 
 moved downward and horizontally. 
 
 PERMANENT WILTING PERCENTAGE: 
 The point at which soil has insufficient 
 moisture to prevent plants from wilting. 
 
 ACRE-INCH: The amount of water that 
 will cover one acre one inch deep — 
 equivalent to a one-inch rainfall. 
 
 PER CENT SLOPE: The fall or rise of 
 land in feet per hundred feet of hori- 
 zontal distance. 
 
 The moisture in the soil which can be 
 considered readily available to the plants 
 is the difference between the field capac- 
 ity and the permanent wilting percentage 
 (PWP). The PWP is usually about half 
 the field capacity. Occasionally, however, 
 the PWP may be as much as four-fifths 
 of the field capacity, in which case more 
 frequent irrigations are needed. Some 
 red soils of the Sierra Nevada foothills 
 have this narrow range between PWP and 
 field capacity. 
 
 IRRIGATION FREQUENCY 
 DEPENDS ON SOIL TYPE 
 
 Because of these different water-hold- 
 ing capacities, you should water sands 
 about twice as often as loams and loams 
 twice as often as clays. This will keep 
 water available to the roots at all times. 
 Applying this principle to a field or oi- 
 chard, you should plan to start irrigating 
 soon enough so that (when several days 
 are required for the complete job) the 
 last plants to be irrigated will receive 
 water before they wilt. 
 
 Some plants, such as young corn and 
 lettuce, have sparse root systems which 
 do not occupy the whole soil mass. There- 
 fore frequent, light irrigations are neces- 
 sary to maintain a supply of moisture 
 immediately adjacent to the roots. 
 
 WHEN TO START 
 IRRIGATING 
 
 Timing the first irrigation depends on 
 how much moisture has been supplied by 
 winter and spring rains. A light winter 
 rainfall which fails to wet the entire root 
 zone will make earlier irrigation neces- 
 sary. 
 
 In the case of annual crops, the soil 
 should usually be irrigated before plant- 
 ing. 
 
 Orchards follow a pattern in their use 
 of water. In deciduous orchards, use is 
 
 [4] 
 
low in spring, reaches a peak in summer, 
 and drops in fall. Citrus, being an ever- 
 green, uses more water in winter than 
 deciduous trees. Both types reach peak 
 use in July and August. 
 
 Irrigation water penetrates the soil a 
 definite distance. The area penetrated — 
 downward and horizontally — is then at 
 field capacity, and the moisture content 
 of adjacent soil remains unchanged. 
 
 An ideal irrigation should wet all of 
 the soil occupied by the plant roots; 
 hence furrows should be spaced close 
 enough to wet all the soil. 
 
 Don't overirrigate. Over-irrigation 
 wastes water and may harm plants. 
 
 Frequently soils which are contour- 
 planted are of limited depth, underlain 
 by bedrock, hardpan, or claypan. Over- 
 irrigation may cause water to collect on 
 these impervious layers, thus creating 
 moisture conditions in excess of field 
 capacity. 
 
 Root- rot in avocado groves and gum- 
 mosis in citrus trees may be caused by 
 such excess water. 
 
 When irrigation water contains large 
 amounts of soluble salts, however, some 
 
 WATER NEEDS OF ORCHARDS 
 
 INCHES OF WATER 
 
 month Deciduous Citrus 
 
 March 1 
 
 April 1 2 
 
 May 3 2 
 
 June '..... 5 3 
 
 July 6 4 
 
 August 6 4 
 
 September 3 3 
 
 October 1 2 
 
 November 1 
 
 overirrigation is desirable. Repeated use 
 of such water can cause an accumulation 
 of salt harmful to plants. A heavy irriga- 
 tion is then necessary to carry the salts 
 below the root zone. 
 
 Tensiometers. Until recently soil mois- 
 ture conditions in the root zone have been 
 determined by the use of soil tubes, au- 
 gers, and excavation. During the past few 
 years tensiometers have been developed 
 to measure the available water held by 
 the soil. With careful use they are relia- 
 ble and practical. University of California 
 Farm Advisors can advise you on their 
 use. 
 
 SOIL TERMS USED IN THIS CIRCULAR 
 
 Fine 
 
 Medi 
 
 lum 
 
 Coarse — 
 
 
 [5] 
 
 EXAMPLE 
 
 Clay 
 
 Loam 
 
 Sand 
 
IS YOUR LAND SUITED TO CONTOUR PLANTING? 
 
 Generally speaking, the best way to 
 determine whether land is suitable for 
 contour planting is to consult local farm- 
 ers who have used the method. The fol- 
 lowing characteristics are particularly 
 desirable in land that is to be contour- 
 planted: 
 
 SOIL DEPTH MUST 
 BE ADEQUATE 
 
 Soil should be deep enough so that 
 leveling operations will not impair its 
 ability to grow a crop. On sloping land 
 the soil is usually shallow: for example, 
 on rolling terrace areas the subsoil is clay- 
 pan or hardpan, and on hills the soil is 
 commonly underlain by bedrock. If re- 
 quired leveling operations are very exten- 
 sive, the site is probably not practical for 
 contour planting. 
 
 EROSION LIKE THIS is the result of using too 
 steep a furrow grade. 
 
 MEDIUM TEXTURES 
 ARE PREFERABLE 
 
 Soil should preferably be of a medium 
 texture. Soils such as loams and clay- 
 loams are usually easier to handle and are 
 most productive. Fine soils crack badly on 
 drying and water often breaks out of the 
 furrows. Sandy soils are liable to present 
 a serious erosion problem when furrows 
 break during irrigation or as result of 
 rain. 
 
 IS SLOPE SUITED 
 TO OPERATION? 
 
 When choosing a site, consider the 
 slope of the land, since contour irrigation 
 and other orchard operations become in- 
 creasingly difficult as the slope increases. 
 In practice the deciding factor as to 
 whether a slope is usable is whether or- 
 chard operations can be performed eco- 
 nomically. 
 
 Relatively flat slopes can be irrigated 
 on the natural surface. Cultivation and 
 furrowing on intermediate slopes tend to 
 build up moderate terraces. On slopes 
 steeper than 25 or 30% it is usually ad- 
 visable to build bench terraces (see page 
 24). 
 
 For field crops, vegetable crops, and 
 strawberries the upper limit of slope is 8 
 to 10 // . Steeper inclines can be irrigated, 
 but all cultural practices become increas- 
 ingly difficult. 
 
 DON'T OVERLOOK NEED 
 FOR DRAINAGE 
 
 A practical means for draining off ex- 
 cess water must be at hand. This is im- 
 portant in contour planting to avoid 
 erosion. Excess water from rainfall or 
 irrigation can be removed over grass 
 waterways in swales or through concrete 
 pipes with suitable inlets. 
 
DESIGNING A GOOD FURROW SYSTEM 
 
 The ideal furrow system would wet all 
 of the soil occupied by the crop roots, 
 with a minimum of tail waste, with avoid- 
 ance of waterlogging, and with little or 
 no soil erosion. 
 
 To design such a system, two principal 
 factors must be taken into account : grade 
 of furrow and length of furrow. 
 
 HOW TO DETERMINE 
 THE FURROW GRADE 
 
 The diagram below shows how two va- 
 riable elements — soil texture and steep- 
 ness of the land — affect the choice of the 
 most efficient furrow grade to use in a 
 particular situation. Results obtained will 
 be approximations only. 
 
 THIS DIAGRAM WILL help you make a rough estimate of the furrow grade best suited to your 
 land Example A: You have a piece of land with an 8% average slope and coarse-textured soil. 
 To plant and irrigate on the contour, your furrow grade should be about 1.4%. Example B: Your 
 soil is medium-textured on a 15% slope— your furrow grade should be 2.2%. Example C: Your 
 soil is fine-textured and your slope 22%— your furrow grade should be 2.9%. 
 
 [7] 
 
"■••"•: •■■ ', 
 
 AS SLOPES become steeper, the lower side of 
 the furrow is more likely to be overtopped by 
 the water in the furrow. Diagram above shows 
 why the practical limit of slope for this type of 
 furrow is about 20%. Another type of furrow 
 can be constructed by turning the soil down 
 hill only. Such furrows, if carefully constructed 
 and maintained, can be used for somewhat 
 steeper slopes. 
 
 Soil texture: Coarse soils erode read- 
 ily, so grades should be kept fairly flat. 
 Medium soils resist erosion better; there- 
 fore intermediate furrow grades can be 
 used. Fine soils are most resistant to ero- 
 sion ; consequently furrow grades may be 
 steeper. Gravelly or rocky soils are also 
 suitable for steeper furrow grades, be- 
 cause as water flows down the furrow it 
 exposes the gravel and rocks on the fur- 
 row bottom. This material protects the 
 soil underneath from erosion. 
 
 Steepness of land: The stippled part of 
 the diagram on page 7 slants upward 
 from left to right, indicating that steeper 
 slopes require steeper furrow grades. The 
 reason why steeper grades are necessary 
 can be seen in the diagram at left, which 
 shows how irrigation water is more apt to 
 overtop a furrow as land becomes steeper. 
 
 Steeper furrow grades compensate for 
 steeper slopes by increasing the velocity 
 of the irrigation water and thereby de- 
 creasing its depth. 
 
 Occasionally it is impractical to grade 
 land smooth, with the result that it is 
 difficult to lay out furrows on uniform 
 grades. Under these conditions be careful 
 to make the flatter parts of the furrow 
 steep enough to carry the water. 
 
 Obviously, the furrow grade should not 
 be increased to the point where soil ero- 
 sion will be excessive. 
 
 MATCH LENGTH OF 
 FURROW TO SOIL 
 
 In designing a furrow system it is im- 
 portant to consider how apt your soil is 
 to erode. Long furrows can be used on 
 fine soils but short furrows are necessary 
 on coarse soils because water penetrates 
 coarse soil more easily than fine soil. Fine 
 soil is therefore usually cheaper to irri- 
 gate because fewer pipelines are required. 
 (See table below.) 
 
 Since water enters coarse soil readily, 
 shorter furrows and extra pipelines are 
 required to avoid losing water through 
 deep penetration and to avoid applying 
 so much as to build up a temporary water 
 table on the subsoil. The expense of extra 
 pipelines may make irrigation of coarse 
 soils on steep slopes uneconomical. 
 
 TABLE BELOW shows suggested furrow lengths and irrigation times for different soil textures. 
 Duration of irrigation and length of furrow vary directly with the fineness of the soil. 
 
 LENGTH OF FURROW 
 
 SOIL 
 
 DURATION OF IRRIGATION 
 
 200-400 ft. 
 400-600 ft. 
 600-800 ft. 
 
 Coarse 
 
 Medium 
 
 Fine 
 
 2- 6 hrs. 
 
 6-12 hrs. 
 
 12-24 hrs. 
 
 [8] 
 
CHOOSING A PLANTING LAYOUT 
 THE NEXT STEP . . . 
 
 After you have estimated the most de- 
 sirable grade and length for irrigation 
 furrows, decide on a system of planting. 
 Contour plantings vary greatly in de- 
 tail, since each area presents its own 
 problems and each owner has his own 
 ideas. Two principal systems are illus- 
 trated in this circular; they are the most 
 widely used in laying out contour plant- 
 
 CONTOUR-PLANTING 
 TERMINOLOGY 
 
 Before studying planting systems you 
 should become familiar with contour- 
 
 planting terms. These are illustrated in 
 the diagram below, which shows an or- 
 chard laid out with contour rows and 
 straight up-and-down crossrows. Con- 
 tour rows begin just to the right of the 
 pipeline. Arrows indicate the direction 
 of water flow. Each line may represent 
 several furrows. 
 
 Rows 1 and 2 separate noticeably at 
 the right of the sketch. To fill this space 
 a fill row (B) is inserted as shown. Like- 
 wise a spike row (C) is put between Rows 
 2 and 3. The row that is pinched out be- 
 tween Rows 3 and 4 becomes a stub row 
 (A). 
 
 TERMS USED IN CONTOUR PLANTING 
 
 LINES IN COLOR indicate water flow from pipeline at left. Lines may represent several furrows. 
 Trees connected by dotted lines form contour grade rows, while trees up and down the slope form 
 crossrows. Stub row is shown at A; a fill row at B; and a spike row at C. 
 
 [9] 
 
THERE ARE TWO PRINCIPAL 
 
 
 o 
 
 #cr ^^ X G ^ 
 
 XK "G u ^-° G 
 _-_ G ---G---G---S--°' 
 
 ^^^" /* rV \ *"**"*• . Contour Line , — - — " 
 
 Above and at right, the two planting systems applied to the same topography. 
 
 SYSTEM I— NO CROSSROWS 
 
 SOUTHERN CALIFORNIA citrus orchard is a SYSTEM I — Uniform spacing of trees along a 
 
 variation of System I. contour grade without regard to alignment in 
 
 other direction. 
 
 The main advantage of this system is that it 
 is well suited to steep, irregular topography. It 
 usually results in more trees per acre than 
 System II. 
 
 Up-and-down hill cultivation cannot be prac- 
 ticed, because there are no crossrows. This is 
 probably an advantage, since such cultivation 
 tends to leave mounds around the trees, thus 
 making irrigation more difficult. 
 
 A disadvantage of System I is that broken 
 irrigation furrows are not easy to detect. 
 
ORCHARD LAYOUT SYSTEMS 
 
 \ 
 
 G 
 
 // ' 
 i> 7 CL 
 
 ^ 
 
 P 
 
 /G\ ^G G--G" a 
 
 ^^^ f~\ ^*^^ Contour Line -"" 
 
 ^""""^ "0^^_ G ___. ._.-G--G- i --G 
 
 System II allows fewer trees per acre: above are 65 trees; at left, 73 trees. 
 
 SYSTEM II— STRAIGHT CROSSROWS 
 
 SYSTEM II — The other main system of con- 
 tour planting consists of uneven spacing of 
 trees on the contour grade, with straight cross- 
 rows. 
 
 This planting method usually allows fewer 
 trees per acre and is a little harder to lay out 
 than System I. 
 
 An advantage of System II is that, since up- 
 and-down rows are straight, broken irrigation 
 furrows are more easily detected. 
 
 Also, the distribution, servicing and opera- 
 tion of orchard heaters is simplified. 
 
 Cultivation up and down the slope is pos- 
 sible — but not recommended. It tends to leave 
 trees on mounds. 
 
 System II is best suited to smooth, uniform 
 slopes. 
 
 EXAMPLE OF System II, with relatively straight 
 crossrows. 
 
HOW TO LAY OUT AN ORCHARD 
 
 Tins undertaking requires skill and 
 judgment. To obtain good results you 
 should adopt a step-by-step procedure. 
 First, determine what grade your irri- 
 gation furrows should have, following the 
 chart and instructions on pages 13 and 
 14. This should be done carefully and 
 unhurriedly. You'll find it helpful to ex- 
 amine orchards already planted under 
 conditions similar to those on your land. 
 
 EQUIPMENT NEEDED 
 TO MAKE LAYOUT 
 
 Next, gather your equipment. Best, but 
 most expensive, would be an engineer's 
 level, rod, and steel tape. Less expensive 
 but harder to use would be a farm level, a 
 cloth tape, and a flexible cloth rod tacked 
 on a 1x3 board. A hand level can be 
 substituted for the farm level on small 
 plantings where great accuracy is not 
 necessary. A hand axe, 4-foot stakes, and 
 16-inch stakes complete the equipment 
 list. (Laths cut in three 16-inch lengths 
 make good stakes.) 
 
 On the following pages the directions 
 for laying out a contour-planted orchard 
 are given in text and photographs. 
 
 HOW TO START 
 THE JOB 
 
 Assume that we are facing a tract of 
 side-hill land. The average slope is 10% ; 
 
 TYPICAL PRICES OF 
 EQUIPMENT (1963) 
 
 
 Builder's level with tripod J 
 
 Farm level with tripod 
 
 Engineer's rod with target 
 
 Flexible rod 
 
 Steel tape (100') and engineer's 
 reel 
 
 M 60.00 
 
 70.00 
 
 40.00 
 
 4.00 
 
 45.00 
 35.00 
 23.00 
 
 Steel tape (100') in leather case 
 Cloth tape (100') in leather case 
 
 tract width is 300 feet; the pipeline will 
 be near the left margin; land slope at 
 the pipeline is average for the field ; and 
 the contour rows are to be about 20 feet 
 apart. 
 
 Start the layout in the lower left-hand 
 corner of the field by putting a stake 
 about 6 feet to the right of the pipeline 
 location. From this stake proceed up the 
 hill paralleling the pipeline location and 
 driving stakes every 20 feet. These stakes 
 locate the first tree in each row. 
 
 SECOND STEP: LOCATE 
 THE TREE ROWS 
 
 Now we are ready for the second step 
 — locating the direction and grade of the 
 tree rows. Set up the level over the first 
 stake. Bring the rod up close to the level 
 and set the target at the same height as 
 the telescope. 
 
 Assume that the telescope is exactly 5 
 feet above the ground. The target would 
 then be set at 5 feet on the rod. 
 
 The rodman moves across the slope 50 
 feet, as measured by the tape. Since the 
 contour grade is to be 2% [2 feet down 
 for each 100 feet across) , the rodman 
 slides the target up 1 foot on the rod (be- 
 cause the distance across the slope is half 
 of 100 feet) . The reading on the rod then 
 becomes 6 feet, and the rodman moves 
 the rod up or down the slope ( as directed 
 by the levelman) until the center of the 
 target is level with the telescope. At this 
 point the rodman puts a 4-foot stake in the 
 ground. 
 
 The stake, then, marks a spot 50 feet 
 from the first stake and 1 foot lower in 
 elevation. We now have a start on the de- 
 sired 2% grade. 
 
 The rodman moves out another 50 feet 
 across the slope, raising the target on the 
 rod another foot, and the process of sight- 
 ing-in and marking with a stake is re- 
 
 ( Continued on page 17) 
 
 [12] 
 
LEVEL is set up over the first 
 stake, and the target on the 
 rod is set at the same height 
 as the telescope on the level 
 (see photo at right). Stakes 
 locate position of the first tree 
 in each row. Here they are 20 
 feet apart. 
 
 THE ORCHARD 
 
 LAYOUT 
 OPERATION 
 IN PICTURES 
 
 LAYOUT WORK STARTS at 
 first stake in lowest row (see 
 photo below). Rodman (at 
 right) has moved about 50 
 feet, setting target for de- 
 sired grade. Level operator 
 will direct him to move up or 
 down slope until crosshairs 
 in level coincide with center 
 of target. Rodman will then 
 mark that point with a stake 
 and move out another 50 
 feet. Location of pipeline is 
 indicated by the white mark- 
 ers parallel to the line of 
 stakes. 
 
 •*^ 
 
Level is set up 
 over first stake 
 in row. Assume 
 telescope is 5 feet 
 above ground. 
 
 To locate tree row 
 on 2% grade, target 
 on rod is set at 
 6 feet to locate 
 point 50 feet away 
 in the row. 
 
 Target on rod will 
 be set at 7 feet 
 to find this point 
 100 feet away. 
 
 DIAGRAMMATIC representation of the orchard layout operation shown in the photographs that 
 follow. The level and rod settings are assumed. 
 
 I 
 
 RODMAN has now moved 150 feet from level, setting stakes every 50 feet. When all rows have 
 been staked out, the next step (above right) is to mark positions of trees in rows. 
 
 I 1 1. 1 
 
w, 
 
 *"~^ 
 
 ONE MAN holds tape at stake marking position of first tree (at left), while other man drives stake 
 20 feet away. The paper strips have been laid out merely to show the location of the tree rows 
 and, in this instance, as an aid in locating tree positions. However, in actual layout work paper 
 strips are not used. The tree stakes are located on the tree row as indicated by the 4-foot stakes. 
 When all the tree stakes in a row have been located, it may be necessary to move some of them 
 a few inches up or down the hill in order to smooth the curve of the tree row. 
 
 SYSTEM I LAYOUT . . . 
 
 TREE-POSITION stakes have now been driven (the longer grade marker stakes having been re- 
 moved). Note the staggered effect of the stakes, resulting from the uneven spacing of stakes in 
 the rows. This illustrates a System I layout. 
 

 TO LAY OUT an orchard according 
 to System II (straight crossrows), set 
 out two parallel rows of stakes, 
 evenly spaced according to the dis- 
 tance desired between tree cross- 
 rows, as in photo below at left. 
 
 SYSTEM II LAYOUT. 
 
 
 WHILE ONE MAN sights between cor- 
 responding stakes in top and bottom 
 rows, other man drives tree-position 
 stakes in the grade rows (photo at 
 right). 
 
 ~ 3f»m>* 
 
 i 
 
 [16 
 
(Continued from page 12) 
 
 peated. Each stake in the contour row 
 locates a point 1 foot lower than the pre- 
 ceding one. Thus a line of stakes is estab- 
 lished across the slope indicating a 2% 
 grade. 
 
 The practice of driving stakes every 
 50 feet is recommended for average con- 
 ditions. When the cross-slope line makes 
 curves sharper than normal, stakes may 
 be needed every 25 or even every 10 feet, 
 to give an accurate line. When this is nec- 
 essary, the rodman adjusts the target to 
 compensate: For stakes 25 feet apart he 
 would move the target one-half of a foot 
 (6 inches) ; for stakes 10 feet apart he 
 would move the target one-fifth of a foot 
 (2% inches) . 
 
 When the rodman reaches a point 
 about 300 feet away from the level opera- 
 tor or when he is about to disappear from 
 view around the side of the hill, the level 
 operator should move up to the last ac- 
 curately marked point and set up the level 
 over that point. The process of sighting-in 
 is repeated from there. 
 
 The line of stakes is extended as far 
 as it is desired to plant trees. Then the 
 level is brought back to the pipeline, set 
 up over the stake marking the next row 
 uphill, and the staking process is re- 
 peated. Each row is done in the same 
 way, until the rows are all marked out. 
 
 STUB, FILL, AND 
 SPIKE ROWS 
 
 Because of unevenness in topography, 
 the rows will not run exactly parallel to 
 each other. When any row is found to run 
 within less than 18 feet of another row, 
 it should be discontinued; go back and 
 start the next row. The incompleted row 
 is called a stub row. 
 
 When rows separate more than 35 feet, 
 finish the row being worked on, then 
 come back and lay out a row between the 
 two. This is known as a fill row. 
 
 If rows diverge at the far ends, a spike 
 row can be inserted in the same way as 
 the fill row. 
 
 When the rows have been staked out, 
 the spots where trees are to be planted 
 will be marked with 16-inch stakes. 
 
 TREE LAYOUTS FOR 
 SYSTEMS I AND II 
 
 Laying out orchards according to the 
 two planting systems described previously 
 (pages 10-11) calls for two slightly dif- 
 ferent procedures. 
 
 Under System I the trees are to be 
 planted at equal intervals along the con- 
 tour grade row; hence the only problem 
 is to space the tree-marker stakes equally. 
 
 Under System II the trees are to be 
 planted at such intervals along the con- 
 tour grade row as will result in straight 
 crossrows. To achieve straight crossrows, 
 you will need guide lines so that you can 
 align the trees up and down the slope. 
 After you have staked out the row loca- 
 tions, you set up two guide lines at right 
 angles to the pipeline — one near the lower 
 edge of the field, the other near the upper 
 edge. Four-foot stakes are driven at the 
 desired tree-spacing intervals to locate the 
 crossrows. Now, by sighting along the first 
 stakes in each guide line, tree positions 
 can be located on each contour grade line. 
 Other tree locations are aligned in 
 straight crossrows in the same manner. 
 
 HOW TO LOCATE TREES 
 WITH A GRADE BOARD 
 
 A grade board (page 18) is a simple 
 device which may be used instead of a 
 level, rod, and tape to locate the positions 
 of trees on a contour. 
 
 The board should be as long as the de- 
 sired distance between the trees that are 
 to be planted in the orchard — for exam- 
 ple, 20 feet. One end of the board has 
 a fixed, unmovable leg; the other leg is 
 adjustable. The board must be completely 
 rigid over its 20-foot length. 
 
 The short leg may be of any convenient 
 length — say 12 inches. The adjustable leg 
 may then be set to give any desired grade 
 or rate of fall. For trees spaced 20 feet 
 apart on a 1% grade, the adjustable leg 
 should be made 14% inches long. 
 
 [17] 
 
^m 
 
 , i: . 
 
 GRADE BOARD being used to locate positions of trees. Short leg is held at position of first tree 
 in the row; end of board with long leg is moved up or down the slope until the level bubble is 
 centered. The point where the long leg comes to rest is marked with a stake. This will mark posi- 
 tion of second tree. 
 
 LOCATING TREES WITH A GRADE BOARD 
 
 OPERATORS set up third tree position in row. Others are staked out in similar manner. 
 
 I 
 
 C 
 
 w*r:J>* 
 
 
 [18] 
 
Here is how we arrive at the length of 
 14% inches: On a 1% grade a 100-foot 
 row would have a fall of one foot or 12 
 inches. A 20-foot grade hoard is % of 
 100 feet in length. Therefore, in a 20-foot 
 grade hoard the fall would he % of 12 
 inches or ahout 2% inches. Thus the ad- 
 justahle leg would he 12 plus 2% or 14% 
 inches long. 
 
 Now that the grade board is adjusted, 
 how do we use it? The first tree in each 
 row is located — as before — by a stake 
 about 6 feet from the pipeline. Place the 
 short leg of the grade board next to the 
 stake. The other end extends in the ap- 
 proximate direction of the row. Now 
 move the adjustable end of the board up 
 or down the slope until the level bubble 
 is centered. Place the second stake at this 
 point to indicate where the second tree 
 will be, and continue with the same pro- 
 cedure for the remaining tree locations. 
 
 This method of locating trees will re- 
 sult in an orchard without straight cross- 
 rows. 
 
 PLANTING BOARD PUTS TREES 
 WHERE YOU WANT THEM 
 
 Having gone to the trouble and ex- 
 pense of marking the exact points at 
 which trees are to be planted, you can 
 "protect your investment" by using the 
 planting board. This board insures that 
 trees will be spotted exactly where the 
 markers indicate they should be placed. 
 
 The photos at right illustrate how a 
 planting board is used. 
 
 ABOVE, TOP, notch in middle of planting 
 board is placed against tree-marker stake and 
 additional stakes are driven into notches at 
 either end of the board. 
 
 CENTER STAKE and board are then removed 
 and hole dug for the tree, as shown in photo 
 at right. Planting board is replaced and tree 
 positioned in center notch for planting. 
 
 OTHER PUBLICATIONS 
 
 ON RELATED SUBJECTS 
 
 IRRIGATION 
 
 COVER CROPPING 
 
 Essentials of Irrigation and Cultivation of 
 
 Elimination of Tillage in Citrus Soil Man- 
 
 Orchards. Frank J. Veihmeyer and Arthur 
 
 agement. J. C. Johnston and Wallace Sulli- 
 
 H. Hendrickson. California Agricultural Ex- 
 
 van. Extension Circular 150, March, 1949. 
 
 periment Station — Extension Service Circu- 
 
 
 lar 486, revised February, 1960. 
 
 
 [19 
 
SOME POINTERS ON SOIL MANAGEMENT 
 
 There are two reasons why you should 
 cultivate only when absolutely necessary : 
 First, if cultivation isn't necessary it is 
 a waste of time, money, and equipment. 
 Second, if the soil is wet, cultivation tends 
 to pack down the earth beneath the layer 
 cultivated, causing water penetration to 
 be impaired and sometimes even hamper- 
 ing root development. 
 
 However, here are four important rea- 
 sons why orchard cultivation may be de- 
 sirable: 
 
 • To control weeds or annual pests. 
 
 • To prepare land for irrigation. 
 
 • To plant a cover crop. 
 
 • To work in a cover crop. 
 
 THREE COVER CROP AND 
 CULTIVATION SYSTEMS 
 
 Three systems relating to cover crops 
 and cultivation are most common. 
 
 1 — Winter cover crop, summer tillage: 
 This system is practiced under many soil 
 and climatic conditions. A cover crop is 
 established each fall to prevent erosion 
 by winter rains. Often it is necessary to 
 fertilize the crop for adequate growth. In 
 spring, the crop should be worked into 
 the soil to keep it from competing with 
 the trees for moisture and to permit in- 
 stallation of new furrows. 
 
 2 — Permanent cover crop, no tillage: 
 Under this system, furrows are installed 
 and the crop allowed to grow over the 
 entire surface. Results with this method 
 vary greatly. Consequently it is praised 
 and condemned with equal vigor. In any 
 case, it takes great skill and should be 
 used only after careful study. 
 
 Advantages: 
 
 The system effectively controls soil 
 erosion. 
 
 It gives best results on deep and per- 
 meable soils. 
 
 Disadvantages: 
 
 Rodents in the crop are hard to con- 
 trol; they may injure trees by gnawing 
 bark from the tree near the ground level. 
 
 The system permits growth of unde- 
 sirable and difficult-to-control plants such 
 as Bermuda grass. 
 
 Additional water is needed for the 
 cover crop. 
 
 The cover crop can cause fertility 
 problems. 
 
 The cover crop may grow so large 
 it hinders operations. And the dry mate- 
 rial, after mowing, can be a fire hazard. 
 
 3 — No cover crop, no tillage: Weed 
 control with oil and chemical sprays has, 
 in recent years, focused attention on this 
 practice which is spreading rapidly in 
 citrus areas and is being used experimen- 
 tally in deciduous orchards. 
 
 An advantage of this system is that the 
 soil usually becomes more porous, thus 
 facilitating irrigation. On the other hand, 
 shorter furrows, requiring extra pipe- 
 lines, become necessary to avoid wasting 
 water through deep percolation. 
 
 Weed-control expense is high for sev- 
 eral years but then tapers off. 
 
 DON'T CULTIVATE 
 IN CROSSROWS 
 
 Steep orchards should be cultivated on 
 the contour — not up and down hill. Im- 
 plement marks up and down hill encour- 
 age soil erosion. 
 
 When contour cultivation alone is con- 
 tinued on steeper slopes, bench terraces 
 tend to form. Then, if up-and-down cul- 
 tivation is started, trees are often left on 
 mounds. The resulting uneven ground 
 surface makes irrigation difficult. This 
 can also cause serious erosion from winter 
 rains because runoff is concentrated in 
 low spots. 
 
 [20] 
 
OTHER APPLICATIONS OF CONTOUR PLANTING 
 
 BUSHBERRIES ON 
 THE CONTOUR 
 
 In the coastal region of central Cali- 
 fornia a large area of trellised bushberries 
 is irrigated by contour-grade furrows. 
 The plantings are usually on gently roll- 
 ing land sloping not more than 8%. 
 Grade of rows is about 1%. Since the 
 topography is smooth it is not necessary 
 to use stub, spike or fill rows to any great 
 extent. 
 
 In these plantings the distance between 
 the rows is about 8 or 10 feet. Field oper- 
 ations are generally performed with tools 
 which make only one trip per row. With 
 such a narrow row sharp curves should 
 be avoided as they may impede use of 
 equipment. 
 
 Where a tractor with tools attached is 
 
 to be used, curves may have a radius as 
 short as 20 feet. But when the tools are 
 pulled behind the tractor the curves 
 should have a radius of not less than 30 
 feet. Try out your tractor and tools first, 
 to see how sharply they can turn in the 
 distance between rows you propose to 
 plant. 
 
 In irrigated vineyards, contour plant- 
 ing is not common, but the practice has 
 merit where the land is steep enough to 
 present a soil-erosion problem. 
 
 VEGETABLES ON SLOPES 
 OF 8 TO 10% 
 
 Most vegetable crops are raised on flat 
 bottom land. Some farmers, however, 
 have grown vegetable crops on land slop- 
 
 BUSHBERRIES planted on a contour grade. 
 
 [21] 
 
ing as much as 8 to 10%. Grades of rows 
 seldom exceed 0.5%. Flatter grades are 
 used because the soil surface is bare and 
 is cultivated frequently. These conditions 
 render it very susceptible to soil erosion. 
 
 Higher lands often have the advantage 
 of being more frost-free than bottom land. 
 Also, south and west exposure are notice- 
 ably warmer in winter. 
 
 Disposal of waste water from irriga- 
 tion and rainfall is a serious problem in 
 growing vegetables on the contour. Un- 
 controlled, such water may cause serious 
 gullying. 
 
 One of the best control methods is to 
 establish a grassed waterway for the 
 waste water. Build a wide, shallow ditch 
 and seed it with rye grass or other sod- 
 forming plant. On steep grades it may be 
 well to cover the newly seeded ditch with 
 straw and lightly disk it. Irrigate the 
 ditch carefully until a good stand is ob- 
 
 tained. After that there should be little 
 or no erosion. Lined ditches or concrete 
 pipelines are sometimes used, but these 
 involve substantial cost. 
 
 STRAWBERRIES RAISED 
 ON ROLLING LAND 
 
 Large acreages of strawberries are 
 raised on rolling land, usually on slopes 
 of less than 6%. 
 
 The soils frequently have a dense clay- 
 pan not more than two feet below the 
 surface. Since the soil is shallow, leveling 
 must be limited. 
 
 Laying out a commercial planting on 
 such land is usually done by an expert. 
 
 In strawberry plantings, growers pre- 
 fer rows that are straight, about 125 feet 
 long, and level. These three conditions 
 can be met on suitable land without much 
 leveling, although ingenuity and skill may 
 be needed. 
 
 THIS TYPICAL STRAWBERRY planting on sloping land has a wooden flume in the center of the 
 field unit to supply water. The level rows are irrigated both ways from the flume to the roads 
 at the edges of the field. Since the rows are level the furrows between them are really long, 
 narrow basins which fill at each irrigation. There is no run-off after irrigation or rain and there- 
 fore no waste or soil erosion. Slope of the field is about 6%. 
 
 [22] 
 
w 
 
 LEVEL FURROWS in strawberry field stand full of water just after irrigation. Furrows act as basins; 
 no water is wasted. 
 
 DIVERGING FURROWS in strawberry field indicate that a change in furrow direction was neces- 
 sary to keep furrows level without much land leveling. Irrigation water comes from flume in 
 foreground. 
 
 [23] 
 

 BENCH TERRACES are frequently used on citrus plantings such as shown above and below Con- 
 tour grade rows are laid out as described in text. Next, bench terraces are made, with the bench 
 sloping slightly toward the hil 
 
 Tree rows 
 
 are then staked out near the margin of each bench. 
 
 Co opi ratitvi Extension work in Vgric ulture and Hum, Economics, College of A; 
 perating. Distributed in furtherance of the Acts of Congress of May 8, ami Jm 
 
 culture, University of California, and United Slates Department of Agriculture 
 30, I'M 1. George B. Alcorn, Director, California Agricultural Extension Service. 
 
 15m-8,'63(D7744s)JF