CALIFORNIA 
 AGRICULTURAL EXTENSION SERVICE 
 
 CIRCULAR 57 
 OCTOBER, 1931 
 
 COMMERCIAL FERTILIZERS 
 
 AND SOIL FERTILITY 
 
 IN CALIFORNIA 
 
 P. L. HIBBARD 
 
 Cooperative Extension work in Agriculture and Home Economics, College of Agriculture, 
 University of California, and United States Department of Agriculture cooperating. Distributed 
 in furtherance of the Acts of Congress of May 8 and June 30, 1914. B. H. Crocheron, Director, 
 California Agricultural Extension Service, 
 
 THE COLLEGE OF AGRICULTURE 
 
 UNIVERSITY OF CALIFORNIA 
 
 BERKELEY, CALIFORNIA 
 
 1931 
 
Digitized by the Internet Archive 
 
 in 2011 with funding from 
 
 University of California, Davis Libraries 
 
 http://www.archive.org/details/commercialfertil57hibb 
 
COMMERCIAL FERTILIZERS AND SOIL FERTILITY 
 
 IN CALIFORNIA 
 
 p. L. HIBBARDi 
 
 For proper development and healthy growth, plants need water, 
 air, light, and a favorable temperature. They also need space for roots 
 to form a physical support and from which the plant may derive its 
 mineral nutrients, as well as suitable conditions of soil as to tilth, 
 aeration, and drainage. Another, and most essential requirement, is 
 the need for the substances out of which plant material is formed. 
 These substances may be called plant nutrients. Of these nutrient 
 substances, plants require large amounts of water, carbon dioxide, 
 oxygen, calcium, magnesium, sulfur, nitrogen, phosporus, and 
 potassium. 
 
 Very small amounts of manganese, iron, silicon, boron, zinc, and 
 probably of sodium, chlorine, aluminum, copper, nickel, coba't, and 
 some other elements seem to be essential to healthy normal growth of 
 many if not all kinds of plants. Adequate supplies of all of these ele- 
 ments are usually available to plants in ordinary soils. Excessive 
 amounts of some of them are generally toxic to plants. 
 
 The various substances which plants use, in particular nitrogen, 
 phosphorus, and potassium, are frequently spoken of as plant foods. 
 More correctly it may be said that these substances are the raw mate- 
 rials from which plants synthesize their foods. The plant takes the 
 substances coming from soil, air, and water and combines them in the 
 leaves by aid of light and heat to make sugar, starch, nitrogenous 
 compounds, etc., which are transported to the various parts of the 
 plant, where they are used to produce wood, bark, leaves, flowers, 
 seeds, etc., thus producing the whole plant which we see as perhaps a 
 grass plant, a potato plant, or an apple tree. 
 
 Since most of the mineral substances needed by plants are usually 
 found in sufficient amounts in the soil, only three are commonly 
 considered as fertilizers. These are nitrogen, phosphorus, and potas- 
 sium. Heavy cropping often exhausts the available supply of these 
 elements in the soil so that it becomes necessary to add one or more 
 of them in order to continue to produce good crops. This brings us 
 to the subject of fertilizers. 
 
 1 Associate Chemist in the Experiment Station. 
 
4 California Agricultural Extension Service l^^- 57 
 
 A commercial fertilizer, for the purpose of this discussion, is a 
 material which supplies one or more of these three elements, nitro- 
 gen, phosphorus, and potassium, in considerable amounts and in such 
 condition that it is suitable for absorption by plants. The material 
 should at once easily dissolve in the soil moisture, or soon become 
 soluble by the process of decaying. Many substances, even the soil 
 itself, contain small amounts of these three elements, but not enough 
 to be considered as fertilizers. Other substances contain large amounts 
 of these elements, but not in a condition for plant nutrition. Leather 
 contains much nitrogen but not in a form suitable for nourishing 
 plants. There is much potassium in the mineral feldspar, but this 
 mineral is practically useless as a fertilizer, although considerable 
 amounts of it are present in many soils. 
 
 Organic matter, lime, and sulfur are needed in a good soil, but 
 these are not usually spoken of as commercial fertilizers. 
 
 FUNCTIONS OF THE VARIOUS ELEMENTS IN PLANT NUTRITION2 
 
 Plant physiologists for many years have endeavored to determine 
 the precise function of the various elements needed by plants. Some- 
 thing is now known, though it is still impossible to answer these 
 questions satisfactorily. For the present purpose it will suffice to 
 consider only the three elements commonly used as fertilizers, namely, 
 nitrogen, phosphorus, and potassium. 
 
 The chemist's symbols, N, P, and K are commonly used to desig- 
 nate the elements nitrogen, phosphorus, and potassium, respectively, 
 in technical literature and that of fertilizers. In the common inexact 
 language of everyday discussion, nitrogen is sometimes confused 
 with, or supposed to be the same as ammonia, in respect to its func- 
 tion as a fertilizer. Phosphorus, phosphoric acid, and phosphate, are 
 quite different substances, though these names are often used as if 
 synonomous in common speech. Also potash and potassium are fre- 
 quently used as if these words meant the same thing, though these 
 substances are very unlike. 
 
 In the present discussion, common usage is followed, so that potash 
 or potassium indicate the same thing in a fertilizer; also phosphoric 
 acid, phosphate, or phosphorus may be used somewhat interchange- 
 ably in speaking of phosphorus in fertilizers or plant nutrients. 
 
 2 For a more extended discussion of this subject see: Hoagland, D. E. Fer- 
 tilizer problems and analysis of soils in California. California Agr. Exp. Sta. Cir. 
 317:1-16. 1930. 
 
1931] Commercial Fertilizers and Soil Fertility in California 5 
 
 The following" statements in respect to the functions of the elements 
 nitrogen, phosphorus, and potassium in plant nutrition, are not to 
 be considered as statements of facts, so far as California soils are 
 concerned, but only as a summary of common opinion on the subject. 
 Scientists who have studied the matter most, are still very uncertain 
 about many of the points mentioned. It is not yet possible to make 
 reliable statements as definite as the farmer, or the fertilizer manufac- 
 turer would like to have. 
 
 When any one of the elements, nitrogen, phosphorus, or potassium, 
 is so lacking that growth of plants is much restricted, it is spoken 
 of as the limiting factor if there is an adequate supply of the other 
 two. In case the supply of either of the two is low, one of them may 
 become the limiting factor in plant growth, after the supply of the 
 previously deficient element is made adequate. 
 
 The important point is to produce a favorable condition in the 
 soil for the growth of plants by adding that element in which the 
 soil is deficient. In the majority of cases, California soils are most 
 likely to be deficient in nitrogen. 
 
 Nitrogen (N) is the chief promoter of vegetative growth. Pro- 
 vided other elements are in adequate supply, nitrogen is likely to 
 cause rapid luxuriant growth of dark green foliage. It tends to 
 produce soft, succulent plant tissue such as is desired in lettuce or 
 celery, but not in the straw of grain. Too much nitrogen may make 
 the straw long, soft, and weak, so that the grain falls down in a 
 heavy wind or rain, or, as the farmers say, it 'lodges' badly. How- 
 ever, such effects of nitrogen are very greatly modified by available 
 soil moisture, temperature, sunshine, and time of application of the 
 fertilizer. 
 
 Plants lacking sufficient nitrogen are likely to be small, weak, and 
 yellowish in color, especially in cold, wet spring weather. Grass 
 lacking sufficient nitrogen grows slowly. These various effects of 
 nitrogen may sometimes be modified by the supply of phosporus and 
 potassium, so that for best results an adequate amount of these two 
 as well as nitrogen should be present in the soil. 
 
 Phosphorus (P) is found in both the vegetative and the repro- 
 ductive organs of plants. It is usually present in seeds in a larger 
 proportion than in other parts of the plant. Plenty of easily available 
 phosphorus in the soil often favors early development of an extensive 
 root system of the plant. A large root system is likely to be very 
 advantageous to plants, especially on a poor soil. Also, abundance 
 of available phosphorus is supposed to make the plant healthier and 
 more vigorous so that it is better able to resist disease or insect pests. 
 
6 California Agricultural Extension Service [C^R- ^^ 
 
 Early maturity of many kinds of plants may be promoted by 
 plenty of phosphorus. An excessive supply of phosphorus generally 
 does not injure or make itself evident in abnormal behavior of the 
 plant. This is in great contrast with the effects of excessive nitrogen 
 supply. 
 
 Potassium (K) is absolutely essential to the growth of plants, 
 though it is not yet possible to tell how it operates. Plants suffering 
 from lack of available potassium may be the first to fail under adverse 
 climatic conditions or attack of disease. The somewhat common 
 opinion that addition of potassium to the soil increases the total 
 yield per acre of such crops as potatoes or sugar beets, has not been 
 well supported in California experience, except on peat soils and on 
 some sandy soils. Also, contrary to common belief, there is little 
 evidence that fertilization with potassium makes fruits sweeter. An 
 excess of any potassium salt in the soil (though this is not likely to 
 happen) is injurious to plants, as is an excess of other easily soluble 
 salts, which are commonly spoken of as alkali. 
 
 Since the purpose of this circular is to give information about 
 commercial fertilizers chiefly, the function of other elements needed 
 by plants will not be considered here. Sometimes other substances 
 than nitrogen, phosphorus, and potassium, become limiting factors. 
 In California bad physical condition of the soil, lack of organic 
 matter, and improper moisture conditions may frequently be the 
 limiting factors. 
 
 THE NITROGEN CYCLE 
 
 Plants require large amounts of nitrogen. The air is four-fifths 
 nitrogen, but most plants are unable by means of the leaves or roots 
 to assimiliate air nitrogen, that is, free or uncombined nitrogen, at 
 least not in important amounts. Therefore it is absorbed from the 
 soil through the roots. This nitrogen is always taken up in a state 
 of chemical combination, usually as nitrate, sometimes as an am- 
 monium salt. The plant utilizes the nitrogen from these compounds 
 and recombines it with carbon, hydrogen, oxygen, phosphorus, and 
 sulfur to form a great variety of vegetable substances. When plant 
 residues go back to the soil and decay, these various nitrogen com- 
 pounds in the plant material are changed by soil bacteria back to their 
 original form, ammonium salts and nitrates, which are then ready 
 for use by other plants. This series of changes in the form of com- 
 bination of the nitrogent is known as the nitrogen cycle. The inor- 
 ganic nitrogen in the states of combination known as nitrate and 
 
1931] Commercial Fertilizers and Soil Fertility in California 7 
 
 ammonia is taken up from the soil by plants and made into plant 
 material. When the plant material decays, most of the nitrogen in it 
 is again converted back into its inorganic form, nitrate or ammonia, 
 by certain kinds of bacteria. But at the same time other species of 
 bacteria in the soil may change some of the nitrogen in the plant 
 material back into the form of free nitrogen in which it originally 
 existed in the atmsophere. This free nitrogen is of no use to most 
 species of plants until it has again been changed into the form of 
 nitrate or ammonia and dissolved in the soil moisture. This change 
 may be brought about in two ways, by chemical action in a factory, 
 or by action of some species of bacteria, or perhaps other simple 
 plants in the soil. The nitrogen-fixing bacteria exist chiefly on the 
 roots of plants of the legume family. Under some conditions other 
 nitrogen-fixing organisms, not requiring an association with legumes, 
 may be of considerable importance. 
 
 Most members of the legume family of plants are able to supply 
 themselves with sufficient nitrogen taken from the air by the aid of 
 these nitrogen-fixing bacteria. In this connection, it should be stated 
 that when these legumes find plenty of available nitrogen in the soil, 
 they usually supply their needs from that source instead of fixing free 
 nitrogen from the air. In consequence of this fact, it is usually not 
 possible to cause accumulation of large amounts of fixed nitrogen 
 in the soil at any one time by the growing of legumes. 
 
 Nitrate nitrogen is the most important form of nitrogen for 
 absorption by plants, though ammonium salts are sometimes used. 
 When other forms are given as fertilizers, they are usually converted 
 to nitrate by the soil bacteria before they are utilized by the crop 
 plants. Nitrate nitrogen is easily assimilated by most plants without 
 first having to be converted into some other form. For this reason, 
 it is usually the most useful form in which nitrogen may be used as 
 a fertilizer. Since nitrates are easily soluble in water, they are liable 
 to be washed out of the soil by heavy rains, or by irrigation if too 
 much water is used. Therefore, it is sometimes better to add part 
 of the nitrogen in the form of some organic fertilizer. This will be 
 gradually converted to nitrate as the crop needs it and it is not so 
 likely to be lost in the drainage. Because of the present high cost of 
 organic nitrogen, it may be cheaper to make two or three applications 
 of the less expensive materials which supply inorganic nitrogen. 
 
California Agricultural Extension Service i^^- ^7 
 
 SOURCES OF NITROGEN, PHOSPHORUS, AND POTASSIUM 
 
 Vast amonnts of nitrogen combined as sodium nitrate are found 
 in Chile and some are found in other parts of the world. Small 
 amounts of nitrate are found in arid parts of the United States. Much 
 nitrogen originally contained in plants is now present in coal and 
 coal shales. AVhen coal is made into coke much of its nitrogen may 
 be recovered as ammonium sulfate and this becomes available as 
 a fertilizer. At the present time large amounts of combined so-called 
 * synthetic nitrogen' are being made from the air. The amount thus 
 produced is increasing rapidly. The synthetic nitrogen is placed 
 on the market as nitrate, ammonium salts, urea, or in other combina- 
 tions, which are essentially the same in character and value as the 
 common so-called 'natural fertilizer materials'. Experience with 
 some of the recently introduced combinations is not sufficient to 
 warrant any positive statements as to their value. 
 
 Immense amounts of phosphorus are found in phosphate rock in 
 various parts of the world. The United States has more than is known 
 to exist in any other country. When fertilizers were first beginning 
 to be used, bones were the main source of phosphate and even yet 
 much bone-meal is used as a fertilizer. A considerable amount of 
 the XJhosphorus used as fertilizer is a by-product of steel making, 
 especially in Europe. This substance, known as basic slag or Thomas 
 phosphate, is a very good phosphate fertilizer. It is not easily obtain- 
 able in western United States at the present time. 
 
 Potassium used as a fertilizer, in the past, came mostly from 
 German potash mines. Similar deposits are now beginning to be 
 worked in other parts of the world. There seem to be large amounts 
 of such deposits available in Texas, though they are not yet developed. 
 A superior quality of potassium chloride is now being produced in 
 large an^ounts from Searles Lake, in southern California. Wood 
 a^'.hcs, waste molasses, and sea weed, blast-furnace dust, and cement- 
 mill dust are minor sources of fertilizer potash not ordinarily much 
 used but capable of supplying considerable amounts in cases of 
 emergency. ^ 
 
1931] Commercial Fertilizers and Soil Fertility in California 9 
 
 IMPORTANCE OF ORGANIC MATTER IN THE SOIL 
 
 Organic matter, as found in the soil, consists chiefly of the more 
 or less decomposed remains of plants, such as straw, leaves and roots 
 of previous crops and of manure. Organic matter aids in holding 
 moisture in the soil, makes clayey soil easier to till, increases the 
 rate of penetration of water, and helps to hold sandy soils together. 
 Thus by improving the physical condition of the soil it helps to make 
 fertilizers more effective. 
 
 In a good fertile soil there live a great variety of microscopic 
 plants and animals, mostly bacteria and fungi. Without them a soil 
 is dead and inert like sand or ashes. These small organisms live on 
 oi'ganic matter and decompose it so that the plant food elements 
 which it contains are again made available to furnish nutriment to 
 growing crops. 
 
 Until recent years, farm manures supplied the greater part of the 
 organic matter used on most farms. The supply is now very inade- 
 quate, so that it may become necessary to supply other forms. Well- 
 rotted manure is an excellent source of plant nutrients in most cases. 
 Most manures are extremely variable in composition, usually deficient 
 in available phosphorus and potassium, though some of the dried and 
 pulverized manures now on the market supply much potassium. 
 
 The compost heap which is a pile of any waste material such as 
 straw, leaves, lawn clippings, weeds, etc., mixed with some soil, may 
 be made to spply small amounts of organic matter similar to manure 
 in general character and effects. If kept moist, turned over, and 
 mixed occasionally, the material gradually rots down to a condition 
 very suitable to use on gardens or lawns. 
 
 A process for making manure from straw and other waste vege- 
 table materials was worked out at the Rothamstead Experimental 
 Station in England, a few years ago. The treatment is somewhat as 
 follows : To 1 ton of straw is added a mixture of about 75 pounds 
 ammonium sulfate, 50 pounds superphosphate, and 100 pounds of 
 powdered limestone. This is mixed with the straw. The whole mass 
 is kept moist by frequent watering, and it is occasionally turned over. 
 After about three months, the straw becomes well rotted. The 
 material thus produced is quite similar in appearance, composition, 
 and effects to the ordinary farm manure. Experience with it in the 
 
10 California Agricultural Extension Service l^^- ^7 
 
 United States is still too meager to warrant any very positive state- 
 ments as to its value as a source of organic matter for the soil. The 
 process is patented under the name of ''Adco Process." 
 
 Some of the experiment stations have vv^orked with this process 
 and published information in regard to it. Among them are the 
 New York, Iowa, and Missouri stations. Reports from these stations 
 indicate that the process is feasible, although it is not certain that it 
 will pay the farmers to use this method. 
 
 Some recent research in Germany and in Washington seems to 
 indicate that there is little advantage so far as fertilizing value is 
 concerned, from the use of the artificial manure except from the 
 nitrogen which is added during the process. If this is true, it would 
 be simpler and cheaper to scatter the strawy material on the field 
 without composting, then add the nitrogen fertilizer to the soil 
 directly instead of to the compost. However, this method would lack 
 the advantage of having a well-rotted material which could be easily 
 worked into the soil without interfering with surface cultivation. 
 
 At the present time it is perhaps easier and cheaper to obtain 
 organic matter by means of a covercrop or green manure crop than 
 in any other way. For this purpose legumes are usually best as they 
 can obtain nitrogen from the air. Legumes are plants having irregular 
 winged blossoms, such as alfalfa, clover, beans, peas, melilotus, etc. 
 Other crops such as rye, mustard, or rape furnish a large amount of 
 organic matter but do not fix nitrogen taken from the air. Almost 
 any easily rotted green crop, such as many a common weed, is good 
 for green manure if it contains enough nitrogen to satisfy the needs 
 of the bacteria which cause rapid decay. If the nitrogen content is 
 not adequate this may be supplemented by addition of inorganic 
 sources of nitrogen such as nitrate or ammonium salts. 
 
 What is the best legume or other plant to grow for green manuring, 
 depends on circumstances. Usually it is that one which will give 
 the greatest growth of organic matter at the time when it must be 
 plowed in. The farm advisor or experienced farmer usually knows 
 what is best in his locality. Sometimes the soil is so poor or exhausted 
 by cropping that it will not grow even a good covercrop. It may 
 pay to use a little nitrate to start a covercrop, even a legume crop. 
 Worn out or poor soils may require addition of phosphate or potas- 
 sium or both in order to produce a satisfactory covercrop. When 
 there is very little organic matter in the soil, it may even be necessary 
 to add manure to get a satisfactory covercrop started. 
 
1931] Commercial Fertilizers and Soil Fertility in California 11 
 
 During the decomposition of organic matter in the soil small 
 amounts of several acids are formed. It seems probable that these 
 acids serve a useful purpose in increasing fertility by acting on the 
 raw inert mineral matter of the soil, some of which is thus converted 
 into a condition suitable for plant nutrition. In this way organic 
 matter acts as a fertilizer. 
 
 It is possible for many plants to grow in a soil such as sand, 
 which contains no organic matter, provided suitable fertilizers are 
 adequately supplied. In this way the soil gains in organic matter by 
 accumulation of roots, dead leaves, etc., which thus help to make more 
 plant food available by their decay, as above stated. By this means 
 mineral fertilizers can help to build up a soil by increasing organic 
 matter so that the fertility of the soil will be to some extent self- 
 perpetuating. 
 
 One difficulty with the use of any kind of organic matter in dry 
 countries is that when plowed under it tends to insulate the top soil 
 from the subsoil, so that the top dries out and young plants die. 
 The farmer says they are 'burned out.' To avoid this difficulty, the 
 organic material should be used in moderate amounts at any one 
 time and be plowed or disked in when green, and while the ground 
 is moist so that it will decay promptly and not form a dry layer 
 between top soil and subsoil. Another trouble in the use of organic 
 matter is that during the early stages of decay the bacteria which 
 decompose it may use up all the nitrate in the soil so that none is 
 available to the higher plants which the farmer wishes to grow. Addi- 
 tion of a nitrate fertilizer at this time supplies the necessary nitrogen 
 to the growing crop until the organic matter which has been plowed 
 in is sufficiently decayed to begin to supply nitrate. Legume green 
 manures are preferable because they contain more nitrogen and the 
 difficulty just mentioned is less likely to be troublesome with them. 
 
 The following named legumes are recommended^ as green manure 
 crops for California: 
 
 Winter-growing 
 
 Hubam clover Hairy vetch 
 
 Bitter clover Purple vetch 
 
 Bur clover Woolly-podded vetch 
 
 Garbanzos (Cicer) Monanthos lentil 
 
 Small-seeded horse beans Lupines 
 
 Tangier pea Canadian field peas 
 
 Fenugreek 
 
 3 The list is taken, for the most part, from: Kennedy, P. B. Leguminous 
 plants as organic fertilizers in California agriculture. California Agr. Exp. Sta. 
 Cir. 255:7. 1922. 
 
12 California Agricultural Extension Service [CJir- ^^ 
 
 Summer- growing Alkali tolerant 
 
 ?,«7P!^^ Berseem clover 
 
 J^lf * ^^^^^« Sweet clover 
 
 ^^y^^^^^ Hubam clover 
 
 Mung beans Alfalfa 
 
 Tepary beans Pj^.^.^ ^^^^j^ 
 
 Berseein clover j^^^.^; ^^^^^^ 
 
 Peanuts 
 
 Alfalfa 
 
 Sesbania iieav^/ soil 
 
 Moth bean 
 
 Peas 
 ^«/i4i/ soil Tangier pea 
 
 Bitter clover Horse beans 
 
 Hairy vetch Mimg beans 
 
 Bur clover Sesbania 
 
 Lupines Fenugreek 
 
 Peanuts 
 Cowpeas 
 Soybeans 
 Canadian field peas 
 
 Nonlegumes such as rye, oats, mustard, and buckwheat, and also 
 many common succulent weeds such as malva and pigweed, are some- 
 times used for green manuring. 
 
 SUFFICIENT MOISTURE NECESSARY TO EFFECTIVE 
 USE OF FERTILIZERS 
 
 Most writers on the subject of fertilizers have given little attention 
 to the matter of adequate moisture in the soil. In California or other 
 regions where natural rainfall is not sufficient for the growth of 
 good crops, lack of moisture in the soil is, perhaps more than any other 
 one thing, the limiting factor in successful agriculture. 
 
 Fertilizers can be of little use unless there is sufficient water in 
 the soil to permit good growth of plants. All substances absorbed 
 from the soil by plants must be dissolved in the soil moisture before 
 they can be taken up by the plants. Consequently the farmer should 
 not expect to gain much from application of any kind or amount 
 of fertilizer unless he has means to maintain an adequate supply of 
 moisture in the soil. In California it api)ears that where the natural 
 supply of water is not sufficient to carry the crop to maturity it does 
 not pay to use fertilizers unless water for irrigation is available when 
 needed. It is probably better to have plenty of water and save on the 
 fertilizer. A plentiful supply of plant nutrients in the early portion 
 of the life of the plant may induce such a rank growth that the usual 
 supply of water is inadequate to carry the crop to maturity and so 
 the crop fails. 
 
1931] Commercial Fertilizers and Soil Fertility in California 13 
 
 NEED FOR LIME AND SULFUR IN THE SOIL 
 
 Both lime (calcium) and sulfur are necessary to produce healthy, 
 normal plants. A large proportion of California soils contain suffi- 
 cient amounts of these substances to supply the needs of any ordinary 
 crop. Yet there seem to be some places where soils are improved 
 by the addition of one or both of them. There seems to be no practical 
 method for finding out whether lime or sulfur will be advantageous 
 except to try them. In most places the farm advisor will be able to 
 tell the farmer of the results of experiments with these amendments 
 in his locality. This has no reference to the importance of lime and 
 sulfur in reclamation of alkali land. Usually commercial fertilizers 
 supplying nitrogen, phosphorus, and potassium will give better results 
 where there is no lack of lime or sulfur. 
 
 Ordinary gypsum, which is lime sulfate, supplies both lime and 
 sulfur more cheaply than any other source. Common superphosphate, 
 on the other hand, is about half gypsum, and when much of it is 
 applied to the soil there is likely to be little need for more lime or 
 sulfur so far as plant nutrition is concerned. The farmer who is 
 urged to buy one or the other, or both of these amendments, will do 
 well to try them on a small plot first to see if they do any good, 
 before going to the expense of treating his whole place with them. 
 
 SOIL ANALYSIS NOT A RELIABLE GUIDE TO DETERMINE 
 NEED FOR FERTILIZERS 
 
 To determine with a satisfactory degree of certainty the relative 
 fertility of different soils has long been the objective of soil science, 
 yet the results are often very unsatisfactory. Thus it is quite com- 
 monly believed that a chemical analysis of the soil will show what 
 fertilizer should prove useful. This may be true in a few unusual 
 cases of very poor soil. However, most of our soils contain enough 
 available plant food so that a chemical analysis made by any of the 
 present known methods is no certain guide to the profitable use of 
 fertilizers. It is true that a chemical analysis can show the amounts 
 of the various elements in a soil. But this does not enable the chemist 
 to tell what proportion of any one or all of the essential elements 
 shown by the analysis is in a condition to be useful to plants. For 
 example, a large proportion of the phosphorus and the potassium 
 present in most soils is unavailable to plants. Although this has long 
 
14 California Agricultural Extension Service [^^ ^^ 
 
 been known, soil chemists have not yet found a satisfactory way to 
 measure that portion of the total of these elements which plants can 
 easily take from the soil. 
 
 Further, it may be stated that the cost of an adequate chemical 
 examination of a soil and the difficulty of interpreting the results are 
 so great that such examinations are not made by the University except 
 for research purposes.^ 
 
 No soil needs a fertilizer, but all plants need the elements supplied 
 by a fertile soil. If the soil is lacking in any one of them, the lack 
 may be supplied by a fertilizer. All plants need the same kinds of 
 plant food, but vary in the relative amounts of the different elements 
 which they need. Also different kinds of plants vary greatly in their 
 ability to absorb enough nutrients for their needs from soils poorly 
 supplied with available nutrients. The needs of any single individual 
 plant vary greatly during the different stages of its life period. Nearly 
 all soils contain all of the elements needed by plants, but differ greatly 
 in the rate at which they are able to supply these elements to growing 
 plants. If the soil supplies nutrients too slowly the growth of plants 
 will be slow. 
 
 Some scientists have sought to estimate the so-called ^need' of a 
 soil for fertilizers, by analyzing the plants grown on the soil in 
 question.^ The results have often been disappointing because plants 
 take up more or less of the fertilizer elements somewhat in proportion 
 to the easily available supph^ in the soil. When the supply is large, 
 plants may absorb very much more nitrogen, phosporus, and potas- 
 sium than they need for normal growth. Such excessive absorption 
 of nutrients is known as 'luxury' consumption. Probably it may be 
 considered as largely a waste of plant food. The important point 
 here is that plants may, with little abvantage to themselves or to their 
 grower, absorb from highly fertile soils uselessly large amounts of 
 fertilizer elements. If crops make a good normal growth without 
 fertilizers, it is doubtful whether it will pay to apply them. 
 
 Only actual trials with the particular kind of plant in question 
 can show what is the best fertilizer in any given case. 
 
 4 For a more extended discussion of this subject see: Hongland, D. K.. Fer- 
 tilizer problems and analysis of soils in California. California Agr. Exp. Sta. Cir. 
 317:1-16. 1930. 
 
 5 This does not refer to the Neubauer method now much used in Germany. 
 
1931] Commercial Fertilizers and Soil Fertility in California 15 
 
 HOW MAY THE NEED OF FERTILIZERS BE KNOWN? 
 
 An experienced observer may sometimes be able to detect the lack 
 of certain plant nutrients in a soil by the appearance of vegetation 
 growing on that soil. Some of the indications of need of fertilizers 
 will be mentioned in this connection. Positive proof that fertilizers 
 will pay in any particular case is usually to be had only by actual 
 trial. More than one trial may be necessary. 
 
 Lack of available nitrogen is indicated by slow growth, yellowish 
 instead of dark green leaves, early dropping of leaves of trees, stunted 
 plants, early going to -seed, unfruitfulness. However, some of these 
 appearances may be caused by lack of moisture or other unfavorable 
 conditions. 
 
 Lack of available phosphate is difficult to recognize. It may cause 
 slow development of cereals, late fruiting, low yields, unthrifty 
 appearance. 
 
 Lack of available potash is sometimes indicated by unhealthy 
 plants, susceptibility to disease, brown patches on margins of leaves, 
 and premature dying of leaves from the edge toward the midrib. Too 
 much alkali or salts may have somewhat similar effects. 
 
 EXPERIMENTING WITH FERTILIZERS 
 
 Since soil analysis is, in general, not able to show definitely 
 whether or not a fertilizer will increase profits from a piece of land, 
 the only satisfactory method is to try a fertilizer. Every farmer 
 should be an experimenter to some extent. It is not necessary to 
 make the experimenting very costly or elaborate. A small plot will 
 usually show pretty well the effects of any kind of application, pro- 
 vided such effects are large enough. If the fertilizer application 
 produces no benefit, not much is lost. But if the experiment indicates 
 that the material in question will be helpful or profitable, next year 
 the whole field may be treated, without much risk of great financial 
 loss, although the benefits to be derived from the use of fertilizers 
 may vary greatly with the time of the year and with different years 
 on the same ground. It is very difficult to ascertain the most useful 
 fertilizers for fruit trees, so that the above statements will be only 
 partially, or not at all true of them. 
 
 One who desires to try some experiments may well seek the advice 
 of the county farm advisor, or any other person qualified to give 
 
16 California Agricultural Extension Service l^^^- ^^ 
 
 expert advice on tlie subject. The farm advisor may obtain additional 
 help, if necessary, from the Experiment Station. 
 
 In order to secure reliable results in the use of fertilizers, it is 
 necessary to take into consideration a number of different factors, such 
 as the character of the soil, both physical and chemical, the climate, 
 the kind of crop to be produced, the proximity of a profitable market 
 for the crop, and the commercial value, or acre value, of a crop. It 
 is not possible to make a satisfactory recommendation of fertilizer 
 for any particular crop, without knowing something at least of all these 
 factors. The physical character of the soil will make a. great deal 
 of difference in the way both crops and fertilizers act. The chemical 
 character of the soil determines to a large extent what fertilizers will 
 give the most desirable results. But, as already stated, chemical 
 analysis may frequently be unable to show definitely the capacity of 
 a soil to supply nutrients to a growing crop. Knowledge of the sub- 
 ject of fertilization is not at present complete enough so that it is 
 possible to state with any certainty what will be the effect of the 
 addition of fertilizers on most soils, and upon most crops. In extreme 
 cases of lack of any particular fertilizing substance, or of presence of 
 an unusual amount of any one chief fertilizing substance, it is 
 usually possible to state definitely what will be the effect of addition 
 of a fertilizer, but most soils are in the class between these two 
 extremes, so that the results cannot be definitely foreseen. 
 
 The main purpose of an experiment is to obtain information. 
 The fullest and most useful information is had only by careful 
 planning of the experiment. 
 
 In planning an experiment with fertilizers, a number of points 
 are to be considered : 
 
 1. Have a number of check (untreated) plots between the treated 
 plots, so that results on untreated ground may be compared with 
 those on fertilized ground. Have 'guard' rows or plots between 
 treated plots and the check rows or plots so that there will be no 
 chance for the check plots to be influenced by the material applied 
 to the fertilized plots. 
 
 2. Kepeat each treatment on several plots. 
 
 3. Try it for more than one year. A single season's trial may give 
 very misleading results, especially with trees. 
 
 4. Select a soil as uniformly alike all over as possible on which 
 to lay out the experiment plots. 
 
 5. Make the plots as nearly uniform as possible in size (1/20 
 acre is a good size), slope, and other conditions. Run the plots up 
 and down the slope, if there is a slope, not across it. 
 
1931] Commercial Fertilizers and Soil Fertility in California 17 
 
 6. Select the fertilizers most likely to produce the desired effect. 
 
 7. Try large and small amounts of the fertilizers. 
 
 8. Mark the plots and mark the treatments. 
 
 9. Make a map showing location and treatments of plots. 
 
 10. Keep a written record of all the plots and all the treatments 
 showing location, nature and aniiount of treatment, and results 
 obtained. 
 
 11. Measure and weigh both treatments and crops and record care- 
 fully so that actual figures show the results. It is not safe to draw 
 conclusions from appearance only, in most cases. 
 
 DISAPPEARANCE OF PLANT NUTRIENTS FROM THE SOIL 
 
 Most farmers are aware that the fertility of the soil decreases 
 with use. Many may be interested to know something of how this 
 happens. 
 
 Great quantities of plant nutrients are removed from the soil by 
 crops. If these crops are sold and removed from the land, the soil 
 becomes gradually poorer. The bad effects of this process are to be 
 seen in manj^ places. In New England and the south eastern states 
 they appeared long ago, later in the central states, now they are seen 
 in Kansas and Nebraska, and in a few long-cultivated parts of 
 California. When most of the crops are fed to animals, the manure 
 being returned to the soil and only meat or milk sold, the fertility 
 of the soil may be retained for a long time. 
 
 Where there is much run-off from the land due to rainfall the 
 water carries away some of the richest top soil, and at the same time 
 some nitrogen is lost in the drainage. Such losses by erosion from 
 fertile soils are enormous in some parts of the United States, and most 
 of them are not difficult to prevent. Very little phosphorus or potas- 
 sium are lost in the drainage, as these elements are held very 
 tenaciously by good soils. After these elements have once been 
 thoroughly incorporated in the moist soil it is very difficult to wash 
 them out by water. Most of the nitrogen used by plants is absorbed 
 from the soil in the form of nitrates. These are easily soluble in 
 water and easily washed out by water. To avoid this sort of loss 
 during time of heavy rains, a green crop, called a covercrop, is some- 
 times grown on the soil. This active growth absorbs much of the 
 easily available nitrate nitrogen, converts it into plant substance, 
 and prevents loss. Later when the covercrop is plowed under, the 
 nitrogen is again gradually converted into the nitrate form and thus 
 
18 California Agricultural Extension Service [^^^- ^7 
 
 made available to the next crop. Combined nitrogen in plant material 
 is not easily carried away in the drainage. 
 
 Besides loss of nitrogen in crops and in the drainage, there is 
 sometimes considerable loss from waterlogged soil caused by unde- 
 sirable bacterial action. This may usually be avoided by providing 
 good drainage so that water does not stand long on the land and so 
 that the soil may always contain considerable air. Under some 
 conditions of cultivation, yet imperfectly understood, even when the 
 drainage is good, large losses of nitrogen from the soil to the air may 
 take place, as a result of the activities of certain types of micro- 
 organisms. Such losses sometimes may be much greater than the 
 amount of nitrogen removed by crops. 
 
 Although phosphorus and potassium are not lost from the soil in 
 the same way that nitrogen is, they frequently enter a condition and 
 location in the soil in which they may be of little use to plants. This 
 is due to what is known as fixation. 
 
 J^PIXATION 
 
 When potassium, phosphate, or ammonium salts are added to a 
 soil which contains much clay, from 50 to 99 per cent of the potassium, 
 phosphorus, or nitrogen becomes fixed by the clay almost instantly. 
 The important fertilizing element combines with the clay so that 
 it is not easily washed out by water. This fixation takes place in the 
 top few inches of the soil, that is, in that portion of the soil with 
 which the fertilizer is mixed. In a semiarid climate the feeding roots 
 of trees, alfalfa, and many other plants are frequently far below the 
 surface of the soil. So it is probable that such plants feel little 
 immediate effect of phosphate or potassium fertilizers as usually 
 applied. During the course of many years it is likely that some of the 
 phosphate and potassium will be carried gradually deeper into the 
 soil to a region where they can be absorbed by the roots. Ammonium 
 salts are different, because they are usually converted to nitrates in 
 a few weeks. In this condition the nitrogen is not fixed, but is easily 
 moved through the soil by water. 
 
 The farmer does not want to wait several years for the fertilizer 
 to become accessible to the roots of his plants; he wants immediate 
 results. To this end three methods may be somewhat effective. First, 
 apply the fertilizer in such a way that it will at once be placed deeply 
 in the soil where absorbing roots are most numerous. To do this 
 without injuring the roots special apparatus, not readily available, 
 may be necessary. Second, apply much larger than the usual amounts 
 
1931] Commercial Fertilizers and Soil Fertility in California 19 
 
 of fertilizer. In this way some of it is likely to be carried deeper 
 into the soil before becoming fixed, so that plant roots may have 
 contact with it. When ordinary amounts are not effective, it is sug- 
 gested that heavy applications be tried on a small portion of the 
 field before concluding that fertilizers will do no good. But, too much 
 may act as an alkali, and injure the plants. A third method would 
 be to adopt farming practices which will encourage surface rooting. 
 
 Frequently no useful effect is observed following applications of 
 small amounts of fertilizer. Often there is no lack of available plant 
 nutrients. But, in many cases, if the soil is lacking in available 
 nutrients, it is possible that the failure of the fertilizer is caused by 
 fixation. The fertilizer elements may remain so near the top of the 
 ground that absorbing roots do not come in contact with them. 
 
 Even though the soil may have high fixing power, it is possible 
 for plants to make satisfactory absorption of nutrients from near 
 the top of the ground if important root development takes places near 
 the surface of the soil. Moisture conditions favorable to surface devel- 
 opment of roots may have an important modifying influence. It is 
 fairly well established that, in most soils, plant roots are able to 
 absorb a large part of the fertilizer even though it is fixed by the 
 soil, provided the roots can come into contact with the soil containing 
 the fixed fertilizer. However, in some soils, added phosphate may 
 slowly become entirely unavailable to plants. Some investigators 
 believe that the same may be true of potassium. 
 
 CARRYOVER 
 
 On account of fixation of phosphate, and of potassium, and of the 
 incomplete use of nitrogen compounds added to the soil in organic 
 combinations, a considerable part of the plant nutrients applied to 
 the soil as fertilizers in any one year may remain unused until the 
 next year or longer. In England this 'carryover,' as it is called, is 
 usually allowed for in the renting of land. Experience has enabled 
 farmers to make a reasonably just estimate of the value of the 'carry- 
 over.' A record is kept of the amount and kind of fertilizer applied 
 each year. When a new tenant rents the land he expects to pay for 
 the estimated value of the 'carryover' of fertilizer just the same as 
 though it were in the more tangible form of live stock or implements. 
 
 Experience seems to be the only important available means of 
 estimating the value of fertilizers thus carried over from one year 
 to the next. Some substances, such as farm manures, may have a 
 'carryover' value for several years, not just one season. 
 
20 California Agricultural Extension Service [C^r- 57 
 
 AVAILABILITY OF FERTILIZERS 
 
 The term availability in respect to fertilizers has two quite differ- 
 ent meanings. In relation to plants, available substances are those 
 which plants can readily absorb and utilize. This might be called the 
 agricultural availability of the material. In reference to fertilizers the 
 word available refers to that portion of the total nutritive substance 
 in a fertilizer which is found to be available according to some labora- 
 tory method. This is the commercial availability of the fertilizer. 
 These laboratory methods are designed to show how much of the 
 plant food in any material is ready for immediate absorption by a 
 plant. Although the figure for availability found by any laboratory 
 method is quite abritrary and only roughly indicates how much of a 
 fertilizer may be easily assimilated by plants, it is usually a useful 
 means of comparing different fertilizers to show their relative values. 
 Chemists have spent much time and effort in trying to devise satis- 
 factory methods for determining availability. The results are only 
 partially satisfactory, yet must be accepted until better are found. 
 
 Any fertilizer which is easily soluble in water is considered wholly 
 available ; such fertilizers are nitrates, the ordinary potassium salts, 
 and water-soluble phosphates. Exceptions are ammonium sulfate and 
 urea, which though easily soluble, must have their nitrogen converted 
 to nitrates before they become immediately available to most plants. 
 Nitrification of these materials is usually easy, rapid, and complete, 
 so that they are highly available. Tankage, fish-meal, and bone-meal, 
 gradually become available and are considered high-grade fertilizers, 
 although at the present time they are too expensive for general use. 
 Garbage tankage, leather meal, wool waste, etc., become available so 
 slowly that they are considered as low-grade fertilizers. The availability 
 of these low-grade materials may be much improved by chemical 
 treatment. Rock phosphate is only slowly available to plants, but by 
 treatment with sulfuric acid the highly available superphosphate is 
 produced. 
 
 Although most of the low-grade materials are of little immediate 
 value as fertilizers, they may supply possible plant nutrients at low 
 cost. If the soil contains enough lime and organic matter to make a 
 favorable environment, the low-grade fertilizers gradually become 
 available and may supi)ly plant food more cheaply than the high- 
 grade materials. 
 
 The user of fertilizer should consider carefully the availability 
 of any materials he intends to buy. If he wants immediate results, the 
 fertilizer should be nearly all quickly available. 
 
1931] Commercial Fertilizers and Soil Fertility in California 21 
 
 THE EFFECT OF FERTILIZER RESIDUES ON SOIL AND CROPS 
 
 Most fertilizer materials are, chemically speaking:, salts, A salt 
 consists of two very different parts, an acid and a base. In some 
 cases both the acid and the base may supply plant nutrients. But a 
 number of salts used as fertilizers leave in the soil a residue of acid 
 or base not absorbed by plants. This residue is of little or no use to 
 plants and may be injurious to the soil. Before buying a fertilizer, 
 the farmer should know what residue it may leave and the effect of 
 that residue on soil and crop. 
 
 Sodium nitrate leaves a residue of sodium, which becomes either 
 sodium carbonate or sodium bicarbonate (black alkali) in the soil, 
 unless the soil contains some acid to neutralize them. Ammonium 
 sulfate leaves a residue of sulfuric acid which tends to make the 
 soil acid. Conditions may arise in which such residues are injurious 
 to crop growth, but in California very few cases of this kind have 
 been reported. If these two sources of nitrogen are used together 
 or alternately, the residue left is sodium sulfate, a relative^ less 
 injurious substance. Potassium chloride, often called muriate of potash, 
 leaves a residue of chlorine which is generally not of important magni- 
 tude in comparison with the chlorine already present in the soil or 
 irrigation water. However, in special cases the use of chloride may 
 be open to question. This fertilizer has been used in some places for 
 many years without apparent injury to the soil, especially if used 
 along with organic matter. 
 
 Acid residues are left in the soil by ammonium sulfate, acidulated 
 tankage or fish, leunasalpeter, and some others. Basic or alkaline 
 residues are left by sodium nitrate, calcium nitrate, basic slag, rock 
 phosphate, and bone-meal. Since the basic residue of all of these 
 except sodium nitrate is lime, their residues are generally harmless, 
 sometimes beneficial, tending to correct soil acidity. On certain soils, 
 no bad effects have been noted from ammonium sulfate or sodium 
 nitrate, even when these forms of nitrogen have been used for many 
 years. Each soil condition must be given individual consideration. 
 The same fertilizer may have somewhat different effects on different 
 soils, and even on the same soil at different times or seasons. 
 
22 California Agricultural Extension Service [C^ir. 57 
 
 WHY FERTILIZERS SHOULD BE USED 
 
 Soil fertility, or crop-producing capacity, is diminished by the 
 usual systems of f arming". But labor and other expenses of producing 
 crops may be nearly the same for a poor crop as for a good one. 
 The bigger and better the crop that can be grown on the land, the 
 greater should be the profit. If fertilizers are found to increase crop 
 yields, the increase will cost little more than the price of the fertilizer 
 and additional cost of application and harvesting. It may pay to 
 use fertilizers in amounts up to the point where increased profits 
 cease to be much more than the increased cost. The greatest profits are 
 made by those who secure the greatest average yields of good quality 
 products. But extremely high yields produced by means of applica- 
 tions of excessive amounts of fertilizers may not be profitable because 
 of the great cost of the fertilizer. On the other hand, farming- which 
 produces much less than average yields is not likely to be profitable. 
 If the soil has become so poor through continuous cropping- that 
 farming it no longer pays, it is j^ossible that it will pay to use fer- 
 tilizers. However, some soils are naturally so poor and others become 
 so exhausted by cropping or abuse, that it is not commercially 
 feasible to bring them to good productiveness because of the enormous 
 amounts of fertilizer that would be required. 
 
 To profit by the use of fertilizer, it is necessary to know what 
 and how much to use. If this cannot be learned from the experience 
 of neighbors, or from the farm advisor, it must be found out by field 
 tests with the aid of such scientific knowledge as is available and 
 applicable. If crop yields are decreasing year after year, the cause 
 may be one or more of several conditions, such as : lack of moisture, 
 accumulation of alkali, loss or scarcity of organic matter, bad physical 
 condition, effect of plant diseases or pests, presence of toxic substances 
 developed by continuous growing of one kind of crop, or lack of 
 available plant nutrients. If the last is the cause of poor crops, 
 fertilizers may be the means of securing better yields. If they are 
 already being used, it may be that the quantity is too small, or that 
 the right material is not being used. When a fertilizer is used as an 
 experiment a liberal amount of it should be applied so that there 
 will be no doubt as to its effect. 
 
1931] Commercial Fertilizers and Soil Fertility in California 23 
 
 HOW TO SELECT A SUITABLE FERTILIZER 
 
 It is not possible with present knowledge to give directions insuring 
 certain success in a choice of fertilizer for any particular crop. Some 
 suggestions may be helpful. 
 
 Soil, climate, season, water supply, the particular crop desired, 
 the market for the crop, the time when the fertilizer is to be applied, 
 and other variables should be considered in selecting a fertilizer. 
 Since some of these are not well known in advance and some cannot 
 be controlled, choice of the most effective or best fertilizer for any 
 purpose is partly a matter of chance and partly of experience. Books 
 have been published and experiment stations have issued bulletins 
 making definite recommendations of fertilizer mixtures for certain 
 crops in some definite place. Such advice, if based on experience, 
 may be fairly reliable for the localities concerned. However, in most 
 parts of California neither scientific knowledge nor practical experi- 
 ence is sufficient to warrant such explicit statements. 
 
 The problem consists of two parts, what mixture to use and how 
 much of it to apply. Of course all three, nitrogen, phosphorus, and 
 potassium must be in sufficient supply to make good, normal, healthy 
 plants, but an excess of one or the other may favor the particular 
 kind of growth most wanted. If plants are yellow and grow slowly, 
 nitrogen may be deficient, sometimes iron. If potatoes are soft and 
 watery, potassium and perhaps phosphorus may be needed. In some 
 cases failure of satisfactory growth is not from lack of any of the 
 three main fertilizer elements but from too much of some harmful 
 substance such as manganese, boron, or excessive salts (alkali soil). 
 Too little or too much moisture in the soil is a common cause of poor 
 crops in California. It seems unlikely that ordinary soils lack suffi- 
 cient copper, zinc, boron, manganese, and other elements needed in 
 very small amounts to promote healthy normal growth of plants. 
 Sometimes poor growth is due to excessive lime in the soil so that 
 iron and phosphate are made unavailable. 
 
 In selecting fertilizer mixtures it seems best, unless the soil is 
 already well supplied with them, to include sufficient amounts of 
 potassium and phosphate to balance the nitrogen, since the latter is 
 the expensive part of the mixture and also the part most liable to 
 loss or waste. If some excess of phosphate and potassium, not needed 
 by the crop, is left in the soil it will not be lost, but if sufficient 
 amounts of them are not already present in the soil to permit most 
 
24 California Agricultural Extension Service [Cir- 57 
 
 effective use of the nitrogen, some of this expensive element will be 
 wasted. Experiments in numerous places in California have shown 
 that nitrogen is the element most likely to more than pay for its cost 
 when used as a fertilizer. Of course, if it is known that the soil is 
 well supplied with any of the three, there is little gain to be expected 
 from adding more of the same element. For example, peat soil usually 
 contains plenty of available nitrogen. Experience indicates that 
 usually addition of nitrogen fertilizers to peat in the San Joaquin 
 delta has little or no beneficial effect on crop production. On the 
 other hand, it frequently happens in California that no effect is 
 produced by any other element of the fertilizer than nitrogen. When 
 a fertilizer mixture produces a profitable increase in crop yields, the 
 question should be asked whether the nitrogen alone is responsible. 
 For special crops of high acre value, the cost of fertilizer may some- 
 times become a minor consideration if by the use of large amounts 
 it is possible to secure great profit through larger yields, better 
 quality, or earlier marketability of the crop. In other words, the 
 quantity of fertilizer which can be used advantageously depends on 
 the cost of the fertilizer and the value of the crop. 
 
 FERTILIZERS FOR SPECIAL PURPOSES 
 
 The following notes in regard to fertilizers for certain soils, crops, 
 seasons, etc., are offered merely as suggestions as to what is likely 
 to prove most useful or effective. They are not intended as recom- 
 mendations or directions to be followed without question. Every 
 case where a fertilizer is to be used should be considered as ai;i indi- 
 vidual case to be treated according to its own needs and conditions. 
 [J Sandy soils are liable to be deficient in nitrogen. In humid 
 climates they easily lose fertilizers, and hence frequent light applica- 
 tions of a complete fertilizer not high in nitrogen are suggested. But 
 in California, especially in the drier portions, sandy soils frequently 
 have adequate supplies of phosphate and potash. In this case, only 
 nitrogen fertilizers may be needed. Sometimes organic matter alone 
 may be sufficient. 
 
 f/ Clay soils are usually richer than sands and do not so easily 
 lose plant nutrients. Which of the three, nitrogen, phosphorus, or 
 potassium will be most useful depends upon local and crop conditions. 
 Some of our red hill soils of volcanic origin and some of the poor 
 drab valley loams respond markedly to phosphate for some crops. 
 Peat and muck soils are usually well supplied with nitrogen, but 
 decidedly lacking in available phosphorus and potassium. 
 
1931] Commercial Fertilizers and Soil Fertility in California 25 
 
 Acid soils having: little organic matter are often poor in all plant 
 nutrients. For some crops they should be given a complete fertilizer, 
 perhaps lime also, and effort should be made to increase the content 
 of organic matter. 
 
 Alkali soils usually contain a good supply of i)lant nutrients, but 
 the presence of excessive amounts of salts makes them infertile. 
 When the soil is flooded to wash out the undesirable salts there is 
 likely to be a large loss of plant nutrients along with the alkali. 
 Nitrate in particularly is liable to be lost. After the washing out 
 process is completed it may be very helpful in starting a crop on the 
 leached soil to add some nitrate and perhaps a moderate amount of 
 a complete fertilizer. 
 
 In regard to crops, the legumes in general, such as beans, peas, 
 alfalfa, clover, melilotus, etc., are not so likely to need nitrogen on 
 account of their nitrogen fixing i:>ower, but often respond well to 
 phosphate. Most legumes do better in soils well supplied with lime 
 and some of them will hardly grow in very acid soils. It seems that 
 this is partly because the nitrogen-fixing bacteria do not thrive in 
 acid soils. Failure of legumes on some slightly acid soils is some- 
 times caused by lack of available phosphate. 
 
 In order to start almost any crop (even the nitrogen-gathering 
 legumes such as alfalfa) on sandy, poor, or exhausted soil, a moderate 
 amount of readily available nitrogen, in the form of a nitrate, is 
 likely to be very helpful; manure is especially good. This enables 
 the plants to make a quick start at a time when nitrification is slow. 
 Later when the plants have become established they will be much 
 better able to supply their needs from the unproductive soil. 
 
 Fodder crops, such as grain hay, sudan grass, millet, etc., may be 
 greatly increased by ample nitrogen, when moisture and other condi- 
 tions are favorable. But too much nitrogen, especially if phosphate or 
 potassium is deficient, induces a rank soft growth unusually subject 
 to plant diseases. Such rank growth may exhaust the soil moisture 
 too early. Heavy rain or wind is liable to cause such plants to lodge 
 badly. 
 
 Grass lawns are greatly stimulated by nitrogen, especially by 
 nitrate in a cold, wet spring when nitrification is still slow. After the 
 ground becomes warmer and drier, ammonium sulfate is one of the 
 best lawn fertilizers. If all the grass clippings are removed from 
 the lawn, much phosphate and potash will be carried away so that 
 occasionally a complete fertilizer containing nitrogen, phosphorus, 
 and potassium should be spread on the lawn. This is preferable to 
 ordinary manure, which may bring in weed seeds. 
 
26 California Agricultural Extension Service [Gib. 57 
 
 Vegetable gardens need liberal amounts of available plant nutrients 
 to produce healthy, rapid succulent growth. Flower gardens may be 
 treated in the same way. But there is great variation among flowers 
 in response to fertilizers. Great success with flowers is most likely to 
 be obtained only by an understanding study of the fertilizer needs of 
 the individual species. 
 
 METHODS OF APPLYING FERTILIZERS TO THE SOIL 
 
 Fertilizers are distributed by hand, by spreading with a shovel, or 
 by a machine similar to a seeder or a grain drill. The latter is usually 
 best. Sometimes the material may be broadcasted, then harrowed in 
 where it is to be applied in the rows of plants. The best plan is to 
 have a fertilizer distributor attached to the seeder in such a manner 
 that the fertilizer is placed in the ground in front of and a little 
 lower than where the seed is dropped.. Thus it is covered with a 
 little soil before the seed is dropped so that the seed is a little above 
 and out of contact with the fertilizer. The fertilizer should be dropped 
 an inch or more below the seed. Most fertilizers are likely to injure 
 the seed if allowed to come in direct contact with it. Mehring and 
 Cumings have written a good monograph on the subject of fertilizer 
 distributors.*^ 
 
 Jensen says,^ '^A good fertilizer should have the following named 
 properties : 
 
 1. Place the fertilizer in the best location relative to the seed ; 
 
 2. Have uniform rate of delivery ; 
 
 3. Be easily adjustable for different rates of delivery; 
 
 4. Be capable of a wide range of rates of delivery; 
 
 5. Have a hopper large enough so that refilling will not have to 
 
 be inconveniently frequent; 
 
 6. Have visible feed so that the operator may easily see that it 
 
 is working properly; 
 
 7. Have an effective agitator in the hopper so that the material 
 
 will be continuously delivered; 
 
 8. Be easily emptied and cleaned, in order to avoid corrosion 
 
 of the metal parts by the fertilizer." 
 
 « Mehring, A. L., and G. T. Cumings. Factors affecting the mechanical 
 application of fertilizers. U. S. Dept Agr. Technical Bui. 182:1-96. 1930. 
 
 " Jensen, O. F. Methods and equipment for applying fertilizer. Amer. Fert. 
 72:15-21. 1930. 
 
1931] Commercial Fektilizers and Soil Fertility in California 27 
 
 In applying fertilizers to fruit trees or other permanent plants, 
 the great difficulty is to get them clown into the soil where they will 
 be accessible to the feeding roots. Ordinary applications of phosphate 
 or potash on top of the soil are likely to be fixed so near the surface 
 that the trees are little benefited. At present, there seems to be no 
 machine available which can place the fertilizer deep enough for 
 immediate effect on fruit trees. A methods which has been used by 
 Michigan State College consists in boring numerous holes in the soil 
 about the tree with an electric drill. The holes are made deep enough 
 so that the fertilizer can be placed close to the active roots of the tree. 
 
 If the fertilizer material is to be used on a small garden area, and 
 if it is soluble in water, the best plan is to dissolve it in water and 
 sprinkle the solution on the soil or over the plants or a lawn. Imme- 
 diately after this the whole should be well sprayed with water to 
 wash the fertilizer off the plants and carry it into the soil. 
 
 WHEN TO APPLY FERTILIZERS 
 
 ./ 
 
 When to apply a fertilizer depends upon the kind of fertilizer 
 and the crop. So far as the soil is concerned there is perhaps little 
 difference except that nitrates or materials which will soon generate 
 nitrates should not be applied just before heavy rains are likely to 
 occur which might wash away the nitrate into the drainage under- 
 ground. Nitrate is apt to be most helpful to young plants in early 
 springs when the cold, wet soil usually contains very little nitrate 
 after leaching caused by heavy winter rains. Under such conditions 
 the readily available nitrate enables the young plants or a grass lawn 
 to make vigorous early growth before the normal rapid nitrification of 
 the warm summer supplies plenty of nitrate. Organic nitrogen com- 
 pounds should be applied to the soil from two to ten weeks before the 
 time it is desired to have the nitrogen converted to nitrate ready for 
 the plant to absorb. 
 
 With respect to the crop, the time when there is plenty of nitrate 
 available may materially modify the character of the crop and the 
 time it will mature. Much nitrate in the soil near the time of ripening 
 may delay maturity. If an early crop is wanted, nitrate should be 
 scarce during the later portion of the growth period, and some inves- 
 tigators think available phosphate should be plentiful at this time. 
 This is likely to be the ordinary condition in nature. Most of the 
 nitrate is used up in the earlier part of the season, but the growth 
 of the plant is most active toward the end of its growing period when 
 
28 California Agricultural Extension Service [Cte- 57 
 
 most of the nitrate has been used up. At this time the plant roots 
 are setting free in the soil large amoimts of .carbon dioxide, which 
 tends to make phosphate more soluble thus, according to some writers, 
 promoting ripening. Besides prolonging the growth period, nitrate 
 may considerably modify the quality of the product, so that accord- 
 ing to the quality of fruit or grain desired the nitrate should be made 
 available at the proper time to produce the effect wanted. 
 
 So far as the soil is concerned, time of application of phosphate 
 and potassium may be relatively unimportant, but for plants it is 
 best to have a sufficient supply in the soil, ready when it is needed. 
 Many kinds of plants can advantageously use much cf these ele- 
 ments during the early stages of their life. If the supply is ample 
 when they are young, little may be needed later. Other plants need 
 a continuous supply of all nutrients. Here it is impossible to make 
 specific recommendations for different kinds of plants. 
 
 HOW MUCH FERTILIZER TO USE 
 
 How much fertilizer it will pay to use must be determined largely 
 by experience. A high- value crop may warrant use of large amounts, 
 while it may not j^ay to use any on a low- value crop. Usually a small 
 amount of fertilizer causes a much greater increase of crop on a poor 
 soil than on a good soil. Also the gain from the use of each additional 
 amount of fertilizer becomes less and less as more and more of the 
 material is used. It may pay to keep on increasing the amount used 
 as long as the increase in crop more than pays for the fertilizer used. 
 But if good crops are possible without use of fertilizers it is question- 
 able whether it will pay to apply them. Amounts actually used in 
 practice vary from a few hundred pounds to more than a ton per 
 acre. 'Smaller amounts may give no perceptible effect. From one to 
 ten pounds of nitrogen or potassium fertilizers may be given to a 
 single fruit tree, depending on its kind, its size, and on the character 
 of the soil. Rarely much larger amounts of fertilizers may be applied. 
 The amount of fertilizer to be applied to. an annual crop may vary 
 greatly, according to the probable price of the crop in different years. 
 On the other hand, some soils are so poor that it does not pay to try 
 to make them productive by the use of fertilizers in any amount 
 whatever. 
 
 In estimating how much fertilizer to use to the acre, only the actual 
 plant food in the material should be counted, that is, pounds of nitro- 
 gen, phosphorus, and potassium. The farmer should estimate how 
 
1931] Commercial Fertilizers and Soil Fertility in California 29 
 
 many pounds of each of these elements he can use advantageously and 
 calculate how many pounds of the proposed fertilizer will be required 
 to supply the needed plant food, then use that amount. To apply a 
 hundred or a thousand pounds of some mixed fertilizer without reg'ard 
 to its composition is very poor business. Whatever result may follow, 
 it is impossible to know what was the cause, unless the composition 
 and amount of fertilizer applied are known. Table 1 may aid in cal- 
 culating' how much fertilizer to use on areas smaller than an acre, 
 such as lawns or gardens. 
 
 TABLE 1 
 
 Pounds of Fertilizer for Various Areas in Order to Give a Certain 
 
 Eate Per Acre 
 
 Rate per acre 
 
 Corresponding amounts of fertilizer 
 for smaller areas 
 
 
 1,000 square feet 
 
 100 square feet 
 
 1 square yard 
 
 pounds 
 
 pounds 
 
 pounds 
 
 ounces 
 
 100 
 
 2 50 
 
 25 
 
 4 
 
 200 
 
 5 00 
 
 50 
 
 8 
 
 300 
 
 7.50 
 
 75 
 
 12 
 
 500 
 
 12.50 
 
 1 25 
 
 2 
 
 800 
 
 20 00 
 
 2 00 
 
 3 2 
 
 1,000 
 
 25 00 
 
 2 50 
 
 4 
 
 2,000 
 
 50 00 
 
 5.00 
 
 8.0 
 
 THE FERTILIZER CONTROL 
 
 In most states where much fertilizer is used, the sale of fertilizer 
 is supervised by the state so that manufacturers and dealers w^ll oper- 
 ate honestly and the consumer may buy intelligently. In California 
 this supervision is one of the duties of the Division of Chemistry of 
 the State Department of Agriculture. According to the Fertilizer 
 Control Act, all sellers of fertilizers having a value of 8 dollars or 
 over a ton must procure a license from the division of Chemistry, 
 and register with that office the brand names and guaranted composi- 
 tion of all fertilizers they wish to sell in this state. 
 
 Every package of fertilizer offered for sale in California is required 
 by law to have a plainly marked tag or label showing : 
 
 1. Name and address of manufacturer or dealer 
 
 2. Brand name of the fertilizer 
 
 3. Number of pounds in the package 
 
 4. Minimum per cent of nitrogen, phosphoric acid, and potash 
 
 contained in the goods with a statement showing the 
 source or kind of material from which each is derived. 
 
30 California Agricultural Extension Service [C^- ^^ 
 
 These statements made by manufacturers are usually reliable and con- 
 stitute the 'guaranteed analysis.' 
 
 Official inspectors from the State Department of Agriculture Divi- 
 sion of Chemistry go about the state taking samples of fertilizer offered 
 for sale. These samples are analyzed by the chemists of the Division of 
 Chemistry and the results are published in a bulletin which may be 
 obtained by anyone on request to the Division of Chemistry at Sacra- 
 mento. If the composition of the fertilizer is found materially differ- 
 ent from the guaranteed analysis the manufacturer is liable to a fine 
 or loss of his license. 
 
 Any consumer of commercial fertilizer in this state may have a 
 sample of the fertilizer he is buying analyzed by the Division of 
 Chemistry on payment of a fee of 2 dollars. In this way the farmer 
 may know exactly what he gets for his money and be protected against 
 unscrupulous dealers. Also commercial chemists in most of the larger 
 cities will analyze fertilizers for anyone. 
 
 WHERE TO OBTAIN FERTILIZERS 
 
 Small amounts of fertilizer are sold by some grocers, hardware 
 stores, feed stores, and florist shops. Lots of 100 pounds or more are 
 supplied by regular dealers in fertilizers in the principal cities. The 
 report of the State Department of Agriculture Division of Chemistry 
 contains a list of all licensed manufacturers and dealers in the state. 
 The list for 1930 is given below: 
 
 REGISTERED FERTILIZER MANUFACTURERS AND DEALERS8 
 
 The California Fertilizer Act provides that fertilizers can not be 
 legally sold in this state except by those manufacturers and dealers, 
 and their authorized agents, who have obtained certificates of regis- 
 tration from the State Department of Agriculture. No person or com- 
 pany has a right to use any registration number except in connection 
 with the firm name to which the registration certificate of such number 
 has been issued. No person or company to whom a registration number 
 has been assigned has a right to allow any other person or company to 
 use said registration. No agent has a right to use his principal's regis- 
 tration number in connection with his own name. 
 
 The following list of registered fertilizer manufacturers and dealers 
 includes all tliose registered up to December 31, 1930, for the fiscal 
 year ending June 30, 1931 : 
 
 8 Elmore, J. W. Commercial fertilizers agricultural minerals (1930). California 
 State Dept. Agr. Special Publication 104:13-14. 1931. 
 
1931] Commercial Fertilizers and Soil Fertility in California 31 
 
 Advance Fertilizer Works, P. O. Box C, Beverly Hills, Calif. 
 
 Agricultural Chemical Works, Inc., 905 Macy St., Los Angeles, Calif. 
 
 American Cyanamid Sales Co., Inc., Foothill Blvd., Azusa, Calif. 
 
 American Fisheries Co., P. O. Box 796, San Diego, Calif. 
 
 American Potash & Chemical Co., Trona, Calif. 
 
 American Soda Products Co., Moorestown, New Jersey. 
 
 Anaheim Fertilizer Co., Box 231, Anaheim, Calif. 
 
 Bakersfield Market, Inc., 1221 19th St., Bakersfield, Calif. 
 
 Bandini Fertilizer Co., 4139 Bandini Blvd., Los Angeles, Calif. 
 
 Barrett Co., The, 40 Eector St., New York City. 
 
 Bay City Shrimp Co., 736 Sacramento St., San Francisco, Calif. 
 
 Bayle, Lacoste & Co., 6359 Bay St., Emeryville, Calif. 
 
 Big 7 Fertilizer Works, 317 S. New Hampshire Ave., Los Angeles, Calif. 
 
 Blake, Albert W. Seed Co., 1055 Lincoln Ave., Pasadena, Calif. 
 
 Blumer, A. M., 433 California St., San Francisco, Cnlif. 
 
 Brown, Sewnll S. & Co., P. O. Box J, Los Gatos, Calif. 
 
 California Fertilizer Works, 444 Pine St., San Francisco, Calif. 
 
 California Special Fertilizer Co., 1063 E. Walnut St., Pasadena, Calif. 
 
 Central Produce & Fertilizer Co., 106 Weller St., Los Angeles, Calif. 
 
 Chapman, I. S. & Co., Inc., 101 S. E St., San Bernardino, Calif. 
 
 Cia Ind. Jabonera Del Pacifico, S.C.L., Box 827, Calexico, Calif. 
 
 Coast Chemical Co., 1107 E. 12th St., Los Angeles, Calif. 
 
 Coast Fishing Co., 621 S. Fries Ave., Wilmington, Calif. 
 
 Columbia Steel Co., 1409 Kuss Bldg., 235 Montgomery St., San Francisco, 
 
 Calif. 
 Copra Oil & Meal Co., Ltd., 617 E. 1st St., Los Angeles, Calif. 
 Doty, W. H., 243 Lincoln Ave., Pomona, Cnlif. 
 Eureka Fertilizer Co., 1116 E. 48th St., Los Angeles, Calif. 
 Farm Bureau Supply Co., P. O. Box 772, Lindsay, Calif. 
 Fertilspray Co., The, 2318 W. AVashington Blvd. ,^ Los Angeles, Calif. 
 Ford Motor Co., 3674 Sehaefer Road, Dearborn, Mich. 
 Franco-Italian Packing Co., Inc., 231 Fish Harbor Wharf, Terminal Island, 
 
 Calif. 
 Fruit Growers Supplv Co., Box 530, Station C, Los Angeles, Calif. 
 Fuhr, Geo. W., 1033 Solando Ave., Azusa, Calif. 
 G. & M. Products Co., 1244 E. 12th St., Oakland, Calif. 
 Germain Seed & Plant Co., 747 Terminal St., Los Angeles, Calif. 
 Globe Grain & Milling Co., 907 E. 3rd St., Los Angeles, Calif. 
 Great Western Electro-Chemical Co., 9 Main St., San Francisco, Calif. 
 Gross, E. B. Canning Co., Wave St., Monterey, Calif. 
 Growers Fertilizer Co., 429 Davis St., San Francisco, Calif. 
 Halfhill Co., The, 1855 Industrial St., Los Angeles, Calif. 
 Hauser Packing Co., 2300 E. 9th St., Los Angeles, Calif. 
 Inland Fertilizer Co., 4144 Bandini Blvd., Los Angeles, Calif. 
 International Agricultural Corp., 61 Broadwav, New York Citv. 
 Inukai, K. Co., 153 5th St., San Francisco, Calif. 
 
 Italian Food Products Co., Inc., 1687 W. Water St., Lons Beach, Calif. 
 Kellogg, H. Clay, E.F.D. 1, Box 149, Garden Grove, Calif. 
 Krumm Manufacturing Co., 2 Oranp-e St., Redlands, Calif. 
 Lagomarsino, F. & Sons, 712 J St., Sacramento, Calif. 
 Leffingwell Rancho Co., P. O. Box 218, Whittier, Calif. 
 Lilly, Chas. H. Co., 164 W. Hanford St., Seattle, Wash. 
 Los Angeles Chemical Co., 1960 Santa Fe Ave., Los A^s.geles, Calif. 
 McKesson-Western Wholesale Drug Co., 200 S. Los Angeles St., Los 
 
 Angeles, Calif. 
 McNatt, W. E. & Co., 120 E. College St., Covina, Calif. 
 Mailliard & Schmieden, 203 California St., San Francisco, Calif. 
 Meyer, Wilson & Geo. & Co., 601 Federal Reserve Bank Bldg., San Francisco, 
 
 Calif. 
 Miyahara Ferto & Chemical Co., 2714 Hyans St., Los Angeles, Calif. 
 Monarch Fertilizer Co., R.F.D. 2, Box 411, Whittier, Calif. 
 
32 California Agricultural Extension Service l^^^- ^7 
 
 Monroe, S. 11., 5 Cypress Ave., Los Gatos, Calif. 
 
 Mountain Copper Co., Ltd., 112 Market St., San Francisco, Calif. 
 
 Mutual Orange Distributors, 514 E. 8th St., Los Angeles, Calif. 
 
 North American Agricultural Products Co., 923 E. 1st St., Los Angeles, 
 
 Calif. 
 Oehl Packing Co., P. O. Box 234, San Bernardino, Calif. 
 Ogihara, I. S., 613 W. 165th St., Gardena, Calif. 
 Ontario Fertilizer Works, Inc., P. O. Box 351, Ontario, Calif. 
 Ord, R. C, 126 Santa Barbara St., Santa Barbara, Calif. 
 Pacific Bone Coal & Fertilizing Co., 1100 Financial Center Bldg., San 
 
 Francisco, Calif. 
 Pacific Cottonseed Products Corp., 2301 E. 52nd St., Los Angeles, Calif. 
 Pacific Guano & Fertilizer Co., Station ''A", Berkeley, Calif. 
 Pacific Land & Cattle Co., P. O. Box 608, Imperial, Calif. 
 Pacific Portland Cement Co., Ill Sutter St., San Francisco, Calif. 
 Pacific Rendering Co., Box 47, Nestor, Calif. 
 Pacific Trading Co., Inc., 460 Battery St., San Francisco, Calif. 
 Pinkham & Gaither, P. O. Box 457, Lindsay, Calif. 
 Plantabbs, Coi-p., 1214 Court Square Bldg., Baltimore, Md. 
 Plant Food Co., 4in Bandini Blvd., Los Angeles, Calif. 
 Podd, A. J. Agricultural Chemical Co., 644 E. 87th St., Los Angeles, Calif. 
 Producers Cotton Oil Co., P. O. Box 1344, Fresno, Calif. 
 Redlands Oil Co., 3rd and Citrus Aves., Redlands, Calif. 
 Rynveld, F. & Sons, 925 Howard St., San Francisco, Calif. 
 Sacramento Feed & Fertilizer Co., P. O. Box 1143, Sacramento, Calif. 
 San Diego Hiryo Co., care Y. Fujii, Bonita, Calif. 
 San Francisco Milling Co., Ltd., 500 Berry St., San Francisco, Calif. 
 Sea Pride Packing Corp., Ltd., 400 Sansome St., San Francisco, Calif. 
 Sevin-Vincent Seed Co., 855 Front St., San Francisco, Calif. 
 Shelton Co., The, 126 Beale St., San Francisco, Calif. 
 Silverthorn, Fred C. & Sons, 1501 Market St., San Diego, Calif. 
 Southern California Fertilizer Co., 1126 Merchants Exchange Bldg., 
 
 Los Angeles, Calif. 
 Sterling Supply Co., 4071 Bandini Blvd., Los Angeles, Calif. 
 Stimupiant Laboratories, Inc., Nelson Ave. and Rawson St., Long Island 
 
 Citv, N. Y. 
 Struve", Edward F., 749 William St., Pomona, Calif. 
 Sun Fertilizer Co., 2654 E. 23rd St., Los Angeles, Calif. 
 Swift & Co., Vigoro Sales Dept., 916 E. First St., Los Angeles, Calif. 
 Tennessee Copper & Chemical Corp., Glendale-Milford Rd., Lockland, Ohio. 
 Thornton, A. F., Box 72, San Gabriel, Calif. 
 
 United By-Products Co., 4073 Bandini Blvd., Los Angeles, Calif. 
 Valley Fertilizer Co., Santa Maria, Calif. 
 
 Van Camp, Gilbert C, Agent, Municipal Wharf, San Pedro, Calif. 
 Ventura Packing Corp., P. O. Box 266, Ilueneme, Calif. 
 Wada, George I, Arlington and 182nd Sts., Moneta., Calif. 
 Western Meat Co., South San Francisco, Calif. 
 Western Star Vegetable Fertilizer Co., R.F.D. 2, Box 504, Long Beach, 
 
 Calif. 
 Western Sulphur Industries, Inc., 905 Macv St., Los Angeles, Calif. 
 Western Sun Fertilizer Co., 103 W. College St., Covina, Calif. 
 W^ilbur-Ellis Co., 657 S. Anderson St., Los Angeles, Calif. 
 Yamada, Z. Co., 1019 San Julian St., Los Angeles, Calif. 
 
1931] Commercial Fertilizers and Soil Fertility in California 33 
 
 HIGH-GRADE VERSUS LOW-GRADE FERTILIZER 
 
 Some farmers buy fertilizer by the ton and try to get as many 
 tons as possible for their money. For this reason mannfacturers some- 
 times make np low-grade mixtures selling for a low price. In this 
 practice fillers having no fertilizer value are mixed with the real plant 
 nutrients in order to make the mixture cheaper per ton. Such practice 
 is bad for all concerned. There may be some cases where a filler is 
 desirable or useful to maintain proper mechanical condition or to aid 
 in distribution or preservation of the mixture. But modern practice 
 tries to combine materials in such a way that the desired quality is 
 had without use of unnecessary or worthless fillers. This is to avoid 
 the expense of mixing, bagging, and freight on useless material. In 
 most cases the smaller the amount of useless material in a fertilizer, 
 the greater the amount of actual plant nutrients that can be bought 
 for a dollar. Usually low-analysis fertilizers are the most expensive, 
 so far as immediate fertilizing value is concerned. 
 
 In some cases substances inherent in the nature of the material 
 are improperly called fillers. In ordinary superphosphate nearly 
 one-half the weight is gypsum, which is produced in the process 
 of manufacture and is not economically separable from the phosphate 
 which is the chief fertilizer substance in the mixture. The gypsum 
 should not be classed as a filler in this case. Ordinary tankage, which 
 is a high-grade fertilizer, contains considerable inert valueless mate- 
 rial, not intentionally added. This also is not classed as a filler. 
 
 FERTILIZER BRAND NAMES 
 
 Most manufacturers of fertilizers prepare a number of mixtures 
 which are usually sold under brand names. Many of these brand names 
 do not indicate the composition of the mixture but imply that it is 
 designed for some particular crop, soil condition, time of year, or other 
 special purpose. Sometimes these brand mixtures are designed as a 
 result of experience suggesting their value for the special purpose 
 indicated by the name. Frequently, however, these brand names have 
 no significance and serve only to induce the buyer to spend his money 
 for a fanciful name, without relation to the value or suitability of the 
 fertilizer for his particular needs. 
 
 Kecently it has become a common practice to designate fertilizer 
 mixtures by numbers such as 4-10-6, 0-15-5, 10-10-0. In these the 
 
34 
 
 California Agricultural Extension Service [C^- ^^ 
 
 first number indicates per cent nitrogen, the second number, per cent 
 available phosphoric acid, and the third number, per cent potash in the 
 mixture. This system is easily understood, makes no pretenses and 
 gives desirable information as to composition of the goods. But in 
 addition to this, the sources of the several ingi-edients should be 
 plainly stated. 
 
 A fertilizer containing commercial quantities of all three of these 
 elements, nitrogen, phosphorus, and potassium is known as a complete 
 fertilizer. If it contains only one or two of the three principal elements 
 of a fertilizer it is called incomplete. 
 
 VALUATION OF FERTILIZERS BY THE UNIT SYSTEM 
 
 The 'unit' is a convenient expression used in calculating the com- 
 mercial value of fertilizers. A 'unit' is 1 per cent of a ton, which is 
 20 pounds. The price per unit is found by multiplying the price per 
 pound by 20. In buying and selling according to units of fertilizing 
 materials, the seller gets full value for the actual fertilizing material 
 he delivers and the buyer pays for nothing he does not get. Fillers 
 are not paid for. In dealing by this method, a price per unit is agreed 
 to by both buyer and seller. Then a sample is analyzed. The per cent 
 of N multiplied by the price per unit gives the value of the nitrogen 
 in a ton of the fertilizer. In the same way the value of the phosphorus 
 and potassium is found. The sum of the three values is the value per 
 t®n. Table 2 gives an example of this method of calculating the cost 
 of a fertilizer. 
 
 TABLE 2 
 Example of a Valuation of a Fertilizer by the Unit System 
 
 Element 
 
 Per cent 
 
 in 
 fertilizer 
 
 Price 
 
 per pound, 
 
 cents 
 
 Price 
 per unit, 
 (20 lbs.) 
 
 Value per ton of 
 fertilizer 
 
 Nitrogen (N) 
 
 5.00 
 10 00 
 4.00 
 
 20 
 5 
 6 
 
 $4.00 
 1 00 
 1.20 
 
 $4 OOX 5 = S20 00 
 
 Phosphoric acid (P2O5).... 
 Potash (K2O) 
 
 1.00X10= 10.00 
 1.20X4= 4 80 
 
 Total 
 
 
 
 
 $34 80 
 
 
 
 
 
 
 HOME MIXING OF FERTILIZERS 
 
 Home mixing of fertilizers is not favored by fertilizer manufac- 
 turers, since part of their profit is derived from mixing, bagging, and 
 other operations which they are specially prepared for, and which 
 they can do more cheaply and better than the farmer. The chief 
 advantage of home-mixed fertilizers is a reduction in selling costs 
 
1931] Commercial Fertilizers and Soil Fertility in California 35 
 
 which are high for mixed fertilizers. The fanner who uses large 
 amounts of fertilizer and has some storage space and suitable floors 
 for mixing may save considerable in costs of fertilizers by purchasing 
 the materials separately — that is, the so-called 'simples' — and mixing 
 them at home during slack periods when the labor force would not 
 otherwise be profitably employed. Only materials which do not need 
 grinding can be successfully handled in this manner. If only one 
 simple material is to be used or if each fertilizer material is to be 
 applied separately, no mixing is necessary. For the farmer who 
 uses only a few tons a year, home mixing probably would not pay. 
 
 The National Fertilizer Association claims that about one farmer 
 in three who use fertilizer has at some time tried home mixing, and 
 that only one of those three who have tried it continues the practice. 
 The reason assigned is that it does not pay, or it is too much trouble, 
 or that the farmer cannot do it well enough. 
 
 PRICES OF FERTILIZERS 
 
 The prices of fertilizer materials quoted in table 3 are only 
 approximate, at best. They represent the approximate retail cost of 
 the materials in ton lots at shipping points on the San Francisco Bay 
 in July, 1929. The prices of some of these materials are subject to as 
 much as a 20 per cent change over a few months' time. These quota- 
 tions are given in order to permit the prospective buyer to make a 
 rough estimate of the commercial value of different materials. Before 
 buying a considerable quantity of fertilizer, one should obtain price 
 quotations from more than one dealer in these materials. 
 
 Some of these substances have such undesirable physical qualities 
 that they are disagreeable or difficult to handle and apply to the field. 
 The inexperienced person should always obtain the advice or assistance 
 of one who knows them well before buying or attempting to use any 
 of these fertilizers with which he is not well aquainted. The prices of 
 dried blood, tankage, fish tankage, cottonseed meal, and raw-bone meal 
 are relatively high because these materials are much used as feeding 
 stuffs, for which purpose they are more valuable than for fertilizers. 
 
 Bird guano and bat guano, formerly common, are now very scarce. 
 Basic slag is common as a fertilizer in parts of Europe, but not at 
 present in the United States, particularly in the Far West. Tobacco 
 stems and some of the low-grade potash salts frequently used in 
 eastern United States are rarely used on the Pacific Coast. 
 
 No prices are given for several materials which are not at present 
 available in commercial quantities in this locality. 
 
36 
 
 California Agricultural Extension Service 
 
 [GiR. 57 
 
 TABLE 3 
 
 Approximate Content, Cost Per Unit, and Availability of Plant Food 
 IN Commercial Fertilizers* 
 
 Name of material 
 
 Nitrate of soda 
 
 Nitrate of lime 
 
 Leunasalpeter 
 
 Calurea 
 
 Sulfate of ammonia 
 
 Cyanamide 
 
 Ammophos 
 
 Nitrophoskal 
 
 Diammonophos 
 
 Potassium nitrate 
 
 Leunaphos 
 
 Urea 
 
 Ammonium potassium nitrate .. 
 
 Dried blood 
 
 Tankage 
 
 Fish meal 
 
 Bat guano 
 
 Bird guano 
 
 Cottonseed meal 
 
 Sheep manure 
 
 Chicken manure 
 
 Tobacco stems 
 
 Garbage tankage 
 
 Hoof, hair, leather, feathers, etc 
 
 Peat 
 
 Barnyard manure 
 
 Superphosphate 
 
 Treble superphosphate 
 
 Phosphate of potash 
 
 Basic slag 
 
 Raw bonemeal 
 
 Steamed bonemeal 
 
 Rock phosphate, ground 
 
 Potassium sulfate 
 
 Potassium muriate 
 
 Manure salt 
 
 Kainit 
 
 Carbonate of potash 
 
 Wood ashes 
 
 Kelp 
 
 By-product potash 
 
 Composition of material, 
 per cent of 
 
 N 
 
 PiOst 
 
 KsOt 
 
 15 
 
 
 
 
 
 15 
 
 
 
 
 
 26 
 
 
 
 
 
 34 
 
 
 
 
 
 20 5 
 
 
 
 
 
 20-25 
 
 
 
 
 
 16 
 
 20 
 
 
 
 15 
 
 15 
 
 20 
 
 21 
 
 53 
 
 
 
 13 
 
 
 
 44 
 
 20 
 
 20 
 
 
 
 46 
 
 
 
 
 
 16 
 
 
 
 28 
 
 12-14 
 
 
 
 
 
 8 
 
 8 
 
 
 
 10 
 
 6 
 
 
 
 5-10 
 
 5-10 
 
 2-10 
 
 5-10 
 
 5-15 
 
 
 
 6-9 
 
 2-3 
 
 1-2 
 
 16 
 
 0.9 
 
 3 
 
 2 3 
 
 2 8 
 
 1.2 
 
 1-3 
 
 
 
 4-9 
 
 2-3 
 
 1 
 
 1 
 
 10-15 
 
 
 
 
 
 2-4 
 
 
 
 
 
 (0.5-1.5) 
 
 (0.4-1.0) 
 
 (0.4-1.0) 
 
 
 
 18 5 
 
 
 
 
 
 48 
 
 
 
 
 
 30-50 
 
 50 30 
 
 
 
 10-25 
 
 
 
 3 7 
 
 23 
 
 
 
 3 
 
 27 
 
 
 
 
 
 32 
 
 
 
 
 
 
 
 50 
 
 
 
 
 
 62 
 
 
 
 
 
 20-30 
 
 
 
 
 
 12-14 
 
 
 
 
 
 15-50 
 
 
 
 
 
 5-10 
 
 
 
 
 
 3-10 
 
 
 
 
 
 10-30 
 
 Availability 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 High 
 
 Good 
 
 Good 
 
 Good 
 
 Good 
 
 Low 
 Very low 
 Very low 
 Medium 
 
 High 
 
 High 
 
 High 
 
 Good 
 
 Good 
 
 Good 
 Very low 
 
 High 
 
 High 
 
 Good 
 
 Good 
 
 Good 
 
 Medium 
 
 Medium 
 
 Medium high 
 
 Cost per unit 
 dollars 
 
 NJ 
 
 4 00 
 
 3 83 
 
 2 98 
 
 3 29 
 3 17 
 
 3 23 
 
 4 00 
 
 6 50 
 6 50 
 
 10 00 
 5 20 
 
 6.00 
 6.00 
 
 P205t K20t 
 
 1 44 
 
 1 46 
 
 2 00 
 2.00 
 
 1 41 
 1 35 
 
 1 10 
 1 00 
 63 
 
 1 40 
 
 2 70 
 2.00 
 
 1 30 
 1 00 
 
 * This list of prices is of the time July, 1929, at San Francisco. 
 
 New synthetic nitrogen fertilizers containing nitrogen, phosphorus, and potassium in various forms 
 and proportions are now being made so that it should not be expected that this list is complete and up 
 to date. 
 
 t In this table the usual commercial designations, P2O5 instead of P, and K2O instead of K, are used 
 in reference to materials supplying respectively phosphorus and potassium. 
 
 t Cost of nitrogen in ammonium compounds is now (April, 1931) much less than when this table was 
 made up. 
 
 H This is one of several varieties manufactured by a certain firm. 
 
1931] Commercial Fertilizers and Soil Fertility in California 37 
 
 In calculating- the prices per unit in fertilizer containing more 
 than one of the three substances, it has been necessary to assign some- 
 what arbitrary values to one or two of them, N, P2O-, K.C^j and obtain 
 the other by difference, using the price per ton as the basis. 
 
 SELECTED READING LIST 
 
 Persons desiring further or more extended information on the 
 subject of fertilizers may find what they want in the following list of 
 publications on this and related subjects: 
 
 Bear, F. E. 
 
 1929. Fertilizers. John Wiley & Sons, publishers, New York. (Excellent 
 American book on fertilizers.) 
 
 California State Department of Agriculture, Division of Chemistry. 
 
 1920-. Commercial fertilizers. California State Dept. Agr. Special Pub- 
 lications. (Bulletins giving reports and analyses of commercial 
 fertilizers are publislied from time to time by the California State 
 Department of Agriculture, Division of Chemistry in the Special 
 Publication Series. The most recent one on the subject is Special 
 Publication 104, published in 1931. Copies of these bulletins may 
 be obtained by writing to the California State Department of 
 Agriculture, Sacramento, California. Similar bulletins are issued 
 by other states and may be obtained by referring to the proper 
 office in the respective states. 
 
 Principles of agricultural chemistry. Chemical Publishing Co., 
 Easton, Pa. 
 
 Fertilizers and manures. E. P. Dutton, New York. (Mostly con- 
 cerned witli English conditions.) 
 Lyon, T. Lyttleton, and H. O. Buckman. 
 
 1922. The nature and properties of soils. MacMillan Co., New York. 
 (Chapters 22 and 23 deal with the subject of fertilizers.) 
 Eussell, E. J. 
 
 1928. Soil conditions and plant growth. Longmans, Green & Co., New 
 York. (The most thorough and modern treatment available, for 
 English conditions.) 
 VOORHIES, E. B. 
 
 1926. Fertilizers. MacMillan Co., New York. 
 
 Wheeler, H. J. 
 
 1913. Manures and fertilizers. MacMillan Co., New York. (An extended 
 treatment, but somewhat out of date.) 
 
 s, G. S, 
 
 1917. 
 
 ,, A. D. 
 
 1921. 
 
AGRICULTURAL EXTENSION SERVICE CIRCULARS 
 
 No. 
 3. 
 5. 
 
 9. 
 10. 
 11. 
 12. 
 13. 
 14. 
 
 15. 
 16. 
 
 17. 
 
 21. 
 
 22. 
 23. 
 24. 
 
 25. 
 26. 
 28. 
 
 Feeding Beef Cattle in California. 
 
 Lettuce : Series on California Crops and 
 Prices. 
 
 Suggestions on Grapefruit Culture in 
 Imperial Valley. 
 
 Diseases and Parasites of Poultry in 
 California. 
 
 Rabbit Raising. 
 
 The Home Preparation of Fruit Candy. 
 
 Cauliflower Production. 
 
 "Wool Production in California. 
 
 The Manufacture of Monterey Cheese. 
 
 Selection and Care of Electrical Equip- 
 ment Used in Dairy Manufacturing. 
 
 Pork Production in California. 
 
 Irrigation of Orchards by Contour Fur- 
 rows. 
 
 Liver Fluke and Stomach Worm of 
 Sheep. 
 
 Bovine Tuberculosis. 
 
 Thinning Sugar Beets. 
 
 Strawberry Culture in California. 
 
 Enterprise Efficiency Studies on Cali- 
 fornia Farms. 
 
 Bush Fruit Culture in California. 
 
 The Home Vegetable Garden. 
 
 Brooding and Pullet Management. 
 
 No. 
 
 29. Control of Pocket Gophers and Moles in 
 
 California. 
 
 30. Elements of Grape Growing in Cali- 
 
 fornia. 
 
 31. Powdery Mildew of the Grape and Its 
 
 Control in California. 
 
 32. What to do About Bovine Tuberculosis. 
 
 33. Rearing Dairy Heifers Free from Tiiber- 
 
 ciilosis and Abortion Disease. 
 
 34. Plum Growing in California. 
 
 35. Alfalfa Production. 
 
 36. Beekeeping for the Beginner in Cali- 
 
 fornia. 
 
 37. Home and Farm Preparation of Pickles. 
 
 38. Alfalfa Varieties and Seed Supply. 
 
 40. Frost Protection in California Orchards. 
 
 41. Prune Culture in California. 
 
 42. Peach Culture in California. 
 
 43. The California Avocado Industry. 
 
 44. Bang's Disease (Infectious Abortion). 
 
 45. Zinc Chloride Treatment for Pear Blight 
 
 Cankers. 
 
 46. Cherrv Culture in California. 
 
 47. Equipment for the Bulk Handling of 
 
 Grain. 
 
 48. The Manufacture of Cottage Cheese. 
 
STATION PUBLICATIONS AVAILABLE FOR FREE DISTRIBUTION 
 
 BULLETINS 
 
 No. 
 
 253. Irrigation and Soil Conditions in the 
 
 Sierra Nevada Foothills, California. 
 263. Size Grades for Ripe Olives. 
 277. Sudan Grass. 
 279. Irrigation of Rice in California. 
 283. The Olive Insects of California. 
 304. A Study of the Effects of Freezes on 
 
 Citrus in California. 
 310. Plum Pollination. 
 331. Phylloxera-resistant Stocks. 
 335. C'ocoanut Meal as a Feed for Dairy 
 
 Cows and Other Livestock. 
 
 343. Cheese Pests and Their Control. 
 
 344. Cold Storage as an Aid to the Market- 
 
 ing of Plums, a Progress Report. 
 
 347. The Control of Red Spiders in Decid- 
 
 uous Orchards. 
 
 348. Pruning Young Olive Trees. 
 
 349. A Study of Sidedraft and Tractor 
 
 Hitches. 
 
 357. A Self-Mixing Dusting Machine for 
 Applying Dry Insecticides and Fun- 
 gicides. 
 
 361. Preliminary Yield Tables for Second- 
 Grow^th Redwood. 
 
 364. Fungicidal Dusts for the Control of 
 Bunt. 
 
 366. Turkish Tobacco Culture, Curing, and 
 Marketing. 
 
 368. Bacterial Decomposition of Olives 
 
 During Pickling. 
 
 369. Comparison of Woods for Butter Boxes. 
 
 370. Factors Influencing the Development 
 
 of Internal Browning of the Yellow 
 Newtown Apple. 
 
 371. The Relative Cost of Yarding Small 
 
 and Large Timber. 
 
 373. Pear Pollination. 
 
 374. A Survey ®f Orchard Practices in the 
 
 Citrus Industry of Southern Cali- 
 fornia. 
 
 379. Walnut Culture in California. 
 
 386. Pruning Bearing Deciduous Fruit 
 Trees. 
 
 388. The Principles and Practice of Sun- 
 
 Drying Fruit. 
 
 389. Berseem or Egyptian Clover, 
 
 392. Fruit Juice Concentrates. 
 
 393. Crop Sequences at Davis. 
 
 394. I. Cereal Hay Production in California. 
 
 II. Feeding Trials with Cereal Hays. 
 396. The Mat Bean^ Phaseolus Aconitifolius. 
 404. The Dehydration of Prunes. 
 
 406. Stationary Spray Plants in California. 
 
 407. Yield, Stand, and Volume Tables for 
 
 White Fir in the California Pine 
 Region. 
 
 408. Alternaria Rot of Lemons. 
 
 409. The Digestibility of Certain Fruit By- 
 
 products as Determined for Rumi- 
 nants. Part I. Dried Orange Pulp 
 and Raisin Pulp. 
 
 410. Factors Influencing the Quality of Fresh 
 
 Asparagus After it is Harvested. 
 
 416. Culture of the Oriental Persimmon in 
 
 California. 
 
 417. Poultry Feeding: Principles and Prac- 
 
 tice. 
 
 418. A Study of Various Rations for Fin- 
 
 ishing Range Calves as Baby Beeves. 
 
 419. Economic Aspects of the Cantaloupe 
 
 Industry. 
 
 420. Rice and Rice By-Products as Feeds 
 
 for Fattening Swine. 
 
 421. Beef Cattle Feeding Trials, 1921-24. 
 423. Apricots (Series on California Crops 
 
 and Prices). 
 
 No. 
 
 425. 
 426. 
 427. 
 
 428. 
 
 431. 
 432. 
 433. 
 
 434. 
 435. 
 
 436. 
 439. 
 
 440. 
 
 445. 
 
 446. 
 447. 
 
 448. 
 
 449. 
 
 450. 
 
 452. 
 454. 
 
 455. 
 
 456. 
 
 458. 
 
 459. 
 
 462. 
 464. 
 
 4 65. 
 466. 
 
 467. 
 468. 
 
 469, 
 470. 
 
 471. 
 
 472. 
 473. 
 
 474. 
 
 475. 
 476. 
 
 477, 
 
 Apple Growing in California. 
 
 Apple Pellination Studies in California. 
 
 The Value of Orange Pulp for Milk 
 Production. 
 
 The Relation of Maturity of California 
 Plums to Shipping and Dessert 
 Quality. 
 
 Raisin By-Products and Bean Screen- 
 ings as Feeds for Fattening Lambs. 
 
 Some Economic Problems Involved in 
 the Pooling of Fruit. 
 
 Power Requirements of Electrically 
 Driven Dairy Manufacturing Equip- 
 ment. 
 
 Investigations on the Use of Fruits in 
 Ice Cream and Ices. 
 
 The Problem of Securing Closer Rela- 
 tionship between Agricultural Devel- 
 opment and Irrigation Construction. 
 
 I. The Kadota Fig. II. The Kadota 
 Fig Products. 
 
 The Digestibility of Certain Fruit By- 
 Products as Determined for Rumi- 
 nants. Part II. Dried Pineapple 
 Pulp, Dried Lemon Pulp, and Dried 
 Olive Pulp. 
 
 The Feeding Value of Raisins and 
 Dairy By-Products for Growing and 
 Fattening Swine. 
 
 Economic Aspects of the Apple In- 
 dustry. 
 
 The Asparagus Industry in California. 
 
 A Method of Determining the Clean 
 Weights of Individual Fleeces of Wool. 
 
 Farmers' Purchase Agreement for Deep 
 Well Pumps. 
 
 Economic Aspects of the Watermelon 
 Industry. 
 
 Irrigation Investigations with Field 
 Crops at Davis, and at Delhi, Cali- 
 fornia, 1909-1925. 
 
 Economic Aspects of the Pear Industry. 
 
 Rice Experiments in Sacramento Val- 
 ley, 1922-1927. 
 
 Reclamation of the Fresno Type of 
 Black-Alkali Soil. 
 
 Yield. Stand and Volume Tables for 
 Red Fir in California. 
 
 Factors Influencing Percentage Calf 
 Crop in Range Herds. 
 
 Economic Aspects of the Fresh Plum 
 Industry. 
 
 Prune Supply and Price Situation. 
 
 Drainage in the Sacramento Valley 
 Rice Fields. 
 
 Curly Top Symptoms of the Sugar Beet. 
 
 The Continuous Can Washer for Dairy 
 Plants. 
 
 Oat Varieties in California. 
 
 Sterilization of Dairy Utensils with 
 Humidified Hot Air. 
 
 The Solar Heater. 
 
 Maturity Standards for Harvesting 
 Bartlett Pears for Eastern Shipment. 
 
 The Use of Sulfur Dioxide in Shipping 
 Grapes. 
 
 Adobe Construction. 
 
 Economic Aspects of the Sheep In- 
 dustry. 
 
 Factors Affecting the Cost of Tractor 
 Logging in the California Pine 
 Region. 
 
 Walnut Supply and Price Situation. 
 
 Poultry Houses and Equipment. 
 
 Improved Methods of Harvesting Grain 
 Sorghum. 
 
BULLETINS — {Continued) 
 
 No. 
 479. 
 
 480. 
 
 481. 
 
 482. 
 483. 
 484. 
 
 485. 
 486. 
 
 487. 
 
 488. 
 
 489. 
 
 490 
 491 
 
 492 
 493, 
 
 I. Irrigation Experiments with Peaches 
 
 in California. II. Canning Quality 
 
 of Irrigated Peaches. 
 The Use, Value, and Cost of Credit in 
 
 Agriculture. 
 Utilization of Wild Oat Hay for Fat- 
 tening Yearling Steers. 
 Substitutes for Wooden Breakpins. 
 Utilization of Surplus Prunes. 
 The Effects of Desiccating Winds on 
 
 Citrus Trees. 
 Drying Cut Fruits. 
 Pullorum Disease (Bacillary White 
 
 Diarrhea of Chickens). 
 Asparagus (Series on California Crops 
 
 and Prices). . 
 
 Cherries (Series on California Crops 
 
 and Prices). 
 Irrigation Water Requirement Studies 
 
 of Citrus and Avocado Trees in San 
 
 Diego County, California, 1926 and 
 
 1927. 
 Olive Thinning and Other Means of 
 
 Increasing Size of Olives. 
 Yield. Stand, and Volume Tables for 
 
 Douglas Fir in California. 
 Berry Thinning of Grapes. 
 Fruit Markets in Eastern A^ia. 
 
 No. 
 
 494. 
 495. 
 
 496. 
 
 497. 
 
 498. 
 499. 
 500. 
 501. 
 502. 
 
 503. 
 
 504. 
 
 505. 
 
 506, 
 507, 
 
 508, 
 509, 
 
 Infectious Bronchitis in Fowls. 
 
 Milk Cooling on California Dairy 
 Farms. _ . ^ _ 
 
 Precooling of Fresh Fruits and Tem- 
 peratures of Refrigerator Cars and 
 Warehouse Rooms. 
 
 A Study of the Shipment of Fresh 
 Fruits and Vegetables to the Far East. 
 
 Pickling Green Olives. 
 
 Air Cleaners for Motor Vehicles. 
 
 Dehvdration of Grapes. 
 
 Marketing California Apples. 
 
 Wheat (Series on California Crops 
 and Prices). t j « 
 
 St. Johnswort on Range Lands ot 
 California. 
 
 Economic Problems of California Agri- 
 culture. (A Report to the Governor 
 of California.) 
 
 The Snowy Tree Cricket and Other 
 Insects Injurious to Raspberries. 
 
 Fruit Spoilage Disease of Figs. 
 
 Cantaloupe Powdery Mildew in the 
 Imperial Valley. 
 
 The Swelling of Canned Prunes. 
 
 The Biological Control of Mealybugs 
 Attacking Citrus. 
 
 CIRCULARS 
 
 No. 
 
 11^. 
 
 117. 
 
 127. 
 178. 
 212. 
 230. 
 
 232. 
 
 239. 
 
 240. 
 
 241. 
 
 244. 
 245. 
 248. 
 
 249. 
 253. 
 257. 
 
 258. 
 259. 
 261. 
 262. 
 265. 
 266. 
 
 269. 
 270. 
 276. 
 
 Grafting Vinifera Vineyards. 
 
 The Selection and Cost of a Small 
 
 Pumping Plant. 
 House Fumigation. 
 The Packing of Apples in California. 
 Salvaging Rain-Damaged Prunes. 
 Testing Milk, Cream, and Skim Milk 
 
 for Butterfat. 
 Harvesting and Handling California 
 
 Cherries for Eastern Shipment. 
 Harvesting and Handling Apricdts and 
 
 Plums for Eastern Shipment. 
 Harvesting and Handling California 
 
 Pears for Eastern Shipment. 
 Harvesting and Handling California 
 
 Peaches for Eastern Shipment. 
 Central Wire Bracing for Fruit Trees. 
 Vine Pruning Systems. 
 Some Common Errors in Vine Pruning 
 
 and Their Remedies. 
 Replacing Missing Vines. 
 Vineyard Plans. 
 The Small-Seeded Horse Bean (Vicia 
 
 faba var. minor). 
 Thinning Deciduous Fruits. 
 Pear By-Products. 
 Sewing Grain Sacks. 
 Cabbage Production in California. 
 Plant Disease and Pest Control. 
 Analyzing the Citrus Orchard by Means 
 
 of Simple Tree Records. 
 An Orchard Brush Burner. 
 A Farm Septic Tank. 
 Home Canning. 
 
 No. 
 
 278. 
 
 279. 
 
 282. 
 
 288. 
 290. 
 292. 
 294. 
 296. 
 
 301. 
 304. 
 305, 
 307, 
 308, 
 310, 
 
 311, 
 312, 
 
 316, 
 
 317, 
 
 318, 
 319 
 320 
 
 321 
 
 Olive Pickling in Mediterranean 
 
 Countries. 
 The Preparation and Refining of Olive 
 
 Oil in Southern Europe. 
 Prevention of Insect Attack on Stored 
 
 Grain. 
 Phylloxera Resistant Vineyards. 
 The Tangier Pea. 
 Alkali Soils. 
 
 Propagation of Deciduous Fruits. 
 Control of the California Ground 
 
 Squirrel. 
 Buckeye Poisoning of the Honey Bee. 
 Drainage on the Farm. 
 Liming the Soil. 
 
 American Foulbrood and Its Control. 
 Cantaloupe Production in California. 
 The Operation of the Bacteriological 
 
 Laboratory for Dairy Plants. 
 The Improvement of Quality m Figs. 
 Principles Governing the Choice, Oper- 
 ation, and Care of Small Irrigation 
 
 Pumping Plants. 
 Electrical Statistics for California 
 
 Farms. 
 Fertilizer Problems and Analysis of 
 
 Soils in California. 
 Termites and Termite Damage. 
 Pasteurizing Milk for Calf Feeding. 
 Preservation of Fruits and Vegetables 
 
 by Freezing Storage. 
 Treatment of Lime-induced Chlorosis 
 
 with Iron Salts. 
 
 16m-9,'31