AH r~ w U 3 c j2 _o T" o iV x c2 ^ r» c <+- U rt o x L* O U 11 p rP ■*"* si V- — u _? -*-> *- CS J- C*E 75 O Of 0 P ^ 3 -' o 0 -a x o o jj £ 4-1 J- (U 1*5 u o—> 5= O - ^ O £ £ • »— ^^ ^ 5" -' 0 K 3 *>,_, -4-1 „ |-! ^ 0 -r ^ ^ ^r". r— -M o T- 9 X r* c S u S£J- +-> C 5 > § b« •2 .as 8 s d cL-.a x « U -t-» 5 0 ° & .2 — +-1 s «s 2 v. 0 EC rrt V +j qr, X 5 rt "S 2 a > - -^ - .2 "° 2 g.S r-1 J, 3 -3 U x 2 en u u O O M Jg j- FLRTILIZLR5: ■Their- Source, Purchase, and Use Written for the Use of Farmers and Fruit Growers, With Special Reference to Citrus Culture. :: :: By CARROLL B. 5MITH SECOND EDITION Revised and Enlarged REDLANDS. CALIFORNIA: CITROGRAPH BOOK PRESS 19 11 COPYRIGHTED 1911 BY CARROLL B. SMITH 9/1 Sfc+3'Jf TO THE READER. This work is designed expressly for those who are forced to use fertilizers and yet have not the time to investigate the subject as they would like to. It is intended to be brief and suggestive of thought to the reader rather than complete and final. Technicalities are avoided and illustrations simplified as much as possible. All the facts and deductions contained are based on the highest authorities on the sub- jects mentioned, and largely on the results of actual experience in California. The author hopes that the matter here given will aid the farmer to choose and purchase his fertilizers most wisely, and help him to get the best possible results from their use. There is no final authority in Nature. Every farmer's problems are his own and he must do his own thinking. The author has tried to present only the well established facts and general PRINCIPLES. A fuller knowledge of these, properly applied, will lead to better results and larger profits. CARROLL B. SMITH. Redlands, California. 579459 Note : This book has cross references throughout ; that is, when a number in parenthesis follows a sentence or paragraph it refers to some other para- graph or sentence having the same number, and treating of the same subject. Any phase of the Fertilizer question can thus be followed throughout the book. FERTILIZERS: Their Source, Purchase and Use SOMETHING ABOUT PLANTS. CIRCULATION. 1. The higher plants (Fruit and Forest trees) have a well defined circulatory system. Beginning with the absorption by the root , hairs of soil moisture, containing dissolved plant food, one set of tissue termed xylem carries this moisture or sap upward into the leaves and is there lost. In the leaf the sap is transformed or elaborated largely by sun- light, according to the plant's nature and needs, and returned to the branches and trunk of the tree and its fruit, by another distinct set of tissue termed phloem. Both these sets of tissue are, roughly speaking, found in the "Cambium" or sap layer of the bark. They are between the real bark and the wood of the tree. Wood is built up on one side and bark on the other. In a cross section of a limb or trunk of a tree these different tissues might be illus- trated, as in Fig. 1. The life of the tree is in the cambium. When we bud or graft it is cambium layer contact we want in both stock and scion. If the cambium is severed completely around the tree it dies. All of the soil derived plant foods enter the tree through its xylem tissue, found in the cambium layer. FERTILIZERS RESPIRATION. 2. Plants have a respiratory system. They ab- sorb oxygen and give off carbonic acid, mostly at night, but during the day more oxygen is given off and carbonic acid absorbed. The leaves and some of the green bark are the respiratory system. Carbon and oxygen thus enter the plant directly from the air as well as by water from the roots. Otctir -Sa,r4; Cow Ironic 84 VU « Tf a oocL HtArt Wood oieL Mi FIGURE 1 TRANSPIRATION. 3. Plants give off water (Transpiration) at all times of day and night. The water escapes at cer- tain pores, called Stomata, of the leaf contained also in very young bark. Water carries the plant food into the plant by way of the roots. The plant foods, changed and elaborated, are retained in the tissue as new growth while the water passes off through the leaves as a vapor. When transpiration exceeds the supply from the roots the plant wilts. If the air is saturated with moisture, plants give off less, but FERTILIZERS 7 on hot days give off more. The leaves of fruit trees may be made large or small by an adequate or inad- equate supply of moisture. \The larger and healthier the leaves, the more plant foodjis>laborated~and the better the growth and the crop. So the transpira- tion system and its healthy activities are very directly connected with the production of fruit. 4. Any serious or prolonged check to the process of transpiration necessitates a long time for full recovery, frequently several years. A severe wilting will show for a year, but a slight wilting usually fully recovers after watering. Thus the importance of a regular and sufficient supply of water is evident. Water is the common carrier of all the plant's food, whether the food is derived from the air or from the soil (13), the only positively known exceptions being the absorption of carbon and oxygen by respiration. The whole movement of water from the root hairs to the leaf and back to other parts of the plant and fruit, is confined to the cambium layer in which are contained the xylem (upward flow) and phloem (downward flow) tissue. LEAVES. 5. A good leaf is essential to the best results. Leaves put the plant in communication with sun- light, under which influence sap is changed and many products, incident and essential to growth, are manufactured. It is believed that all of the plant food brought into the 'tree by water, undergoes some change in the leaf (digestion) before it is finally added to the various tissue of the plant. If the leaf has been stunted or impaired by drought, frost or fire, it manufactures less of the products essential 8 FERTILIZERS to growth. Less water can come into it ; therefore, less water and less food enter the plant. Less sun- light can act on it, and all of the activities of the plant are so reduced that the result is a small crop of undersized fruit. Consequently, a good leaf is essential to the best results. BARK. 6. What has been said of the function of leaves is true, to some extent, of green bark. Old, corky bark may be regarded as the armor or shield to the cam- bium layer. But young, tender bark can carry on the process of respiration of carbon and oxygen, and of transpiration of moisture, and to that extent the transformation of the sap and plant food. Although these activities in bark are very limited, they are sufficient to continue the life of the tree should it ever become defoliated for purposes of transplanting or on account of disease or frost. Under the young bark's continued activity new leaves may start, until finally the plant renews its full health and vigor. ROOTS. 7. The distribution of plant food throughout the soil influences directly, and, with water, the entire development of the root. The absorptive power of the root is in the young, tender rootlets or fibres, by means of root hairs invisible to the eye. These root hairs are distributed along the length of the tender, growing fibre. The end of the fibre has a cap which protects it as it develops and crowds its way between the smallest soil particles. The very tips of roots and fibres cannot absorb moisture or food. FERTILIZERS 9 FIBROUS ROOTS. 8. If the soil is poor, the roots are very long and develop very few fibres and root hairs. But in a rich soil they are short and well branched, often forming a perfect mat of fibres. Under such fertile conditions the root hairs are more numerous and the plant's contact with the soil and its feeding powers are much greater. Consequently, roots develop where the food is. Fertilizers should be applied as deep as possible, so that root development will not be encouraged near the surface. (63) (79). SHALLOW WORK. 9. If the application of fertilizers and water is limited to the top foot the most of the fibres are de- veloped there, and deep ploughing and cultivation become questionable policy. Thick water conserv- ing mulch becomes impossible, (see frontispiece). This is the actual condition where impervious strata or "hard pan" lies near the surface. DEEP WORK. 10. In open, deep soils where water can go down easily, the plant food is more widely distributed and likewise the fibrous roots. Here, deep work and a deep mulch are possible, and in case of water short- age, would be found a great advantage, as there is a better reserve supply in the sub-soil. APPLY FERTILIZER DEEPLY. 11. Present practice applies all fertilizer between the surface and the bottom of the plow furrow. This is unavoidable, even in open soils where the water is easily absorbed. Methods of effecting 10 FERTILIZERS deeper applications without serious root disturbance are unknown. As a result roots are encouraged near the surface, and this fact is the best argument advanced for the use of the most water soluble forms of fertilizer obtainable, as they are more widely dis- tributed by the movement of water. (77) (79). SOILS AND ROOTS. 12. The permeable character of the soil influences the root development, aside from the question of plant food. In clay or adcbe soils there is a limited root development and a resultant smaller tree. "Hard pans" near the surface have the same limit- ing influence. In such soils, more trees can be planted to the acre. Open, free loams or gravelly, sandy loams permit a larger root development and trees should be placed further apart. These are usually local ques- tions, but should be considered by the intending planter. The mechanical or physical nature of the soil should be known to a considerable depth. (20- 22). FERTILIZERS SOMETHING ABOUT SOILS. 13. Of more than seventy elements known to chemistry, fourteen have been found to be essential to plant life. Ten of these are soil derived, and four are derived from the air : Air Derived. Soil Derived. Carbon Calcium Oxygen Silicon Hydrogen Iron Nitrogen Magnesium Manganese Sulphur Chlorine Sodium Potassium Phosphorus These fourteen elements, in varying portions, are peculiar to all plants so far as different species have been examined. 14. All soils, for convenience, may be considered as composed of various portions of: Rock Powder \ Silt \ Clay Humus ) Plant food \ rSand ► or simply Clay Humus Sand is rock powder and may or may not contain silt. Clay is a chemical compound and a very im- portant element of soils, as it retains large amounts of moisture. If too abundant, the soil is intractable 12 FERTILIZERS and hard to manage, and bakes easily and while sand alone is too porous to retain moisture, the addition of a little clay with sand makes the proper balance for retaining moisture and for friability. 15. Humus, decayed organic matter, is absolutely essential as it is the source of the necessary nitrogen. It is a fundamental truth in connection with this sub- ject that there is no fertility without humus. It also influences favorably, as nothing else will, the soil's mechanical condition and moisture content, besides supplying essential plant foods. The humus which plants contribute to the soil not only furnishes all of the soil nitrogen, except that artificially added, but gives life to numerous forms of bacterial life, with which every healthy soil is teeming. We cannot discuss this subject here (86- 89), but it will suffice to say that, without the contribution made by plants to the soil, the micro- scopic forms of life could not exist and they are now regarded as essential to fertility. Indeed, it is pos- sible to inoculate soils with beneficial bacteria, and improve their fertility. A soil may contain sand, clay and humus and yet lack some essential plantfood, hence the last division. But as a rule, sand, clay and humus in proper pro- portions will, for a time at least, supply all the requirements of plant life. The plant requires of the soil that it furnish the ten named soil derived elements, and the soil requires of the plant that it supply humus and such of the air derived elements as are necessary to its own health and fertility. Just what amounts of hydro- gen, oxygen, carbon and nitrogen are absorbed FERTILIZERS 1 3 directly from the air, and how much is contributed by plant life, is not known. But it is generally be- lieved that most of these elements as found in soils are derived from plants, either through the agency of beneficial bacteria or from the decay of vegetable tissue. 16. The character of vegetation changes with the soil. Pure clay soils support very little plant life, as there is no drainage, no ventilation and no yielding to root penetration. The right degree of porosity, due to the presence of sand and humus, allows the roots to enlarge rapidly which in turn nourishes a large plant. Hence the same species of plants will vary in size and appearance according as the nature of the soil encourages or restricts their growth. A well developed root means a well developed plant and vice versa. If potassium or sodium or chlorine are in excess, the soil is alkaline and tolerated by certain classes of plants like the salt bushes, some of the mallows, tussock grass, etc. Peat lands, bogs and meadows have a characteris- tic vegetation. Peat may contain as high as 80% humus or decayed organic matter. Here, nitrogen is naturally in excess and moisture plenty, so that the growth is vigorous and succulent. Tall grasses, and willows thrive here. The well drained "mesa" of the arid west, sup- ports another variety of vegetation and a dense forest cover or leaf mould, still another, according to their moisture holding powers. The various com- binations of sand, clay, humus and plant food are almost infinite. 14 FERTILIZERS 17. Soils vary in chemical composition according to depth. The surface foot or two feet usually con- tains the bulk of the nitrogen, due to the fact that the nitrates are water soluble and the evaporation of moisture at the surface leaves the nitrates and all soluble plant foods there for the benefit of young plants whose roots have not gone deep. Young plants must grow first, and nitrogen produces growth. As the plant matures, its roots penetrate lower into the region where the nitrogen is scarce and where the phosphates, silicon, lime and insoluble elements are more evenly distributed. There, fruit production and maturing of tissue take place. During the time growth is vigorous, fruit produc- tion is limited or impossible even in the case of mature trees when artificially forced to an abnor- mally vigorous growth. 18. While nitrogen is the chief element of growth, other elements of the soil favor fruit production. Phosphorus is definitely known to be one of these. (70). If the fruit producing elements of the soil were abundant on the surface, and nitrogen, relatively deficient there, then fruit trees would be heavily laden before they were taken from the nursery. There is abundant evidence of order and design in the methods of nature. "First the blade, then the ear, then the full corn on the ear," and the soil is so arranged as to effect the order. 19. It is interesting to note briefly that the func- tion of potassium is to mature the growth that nitrogen produces. Where nitrogen is in excess of potassium, as in bogs and peat lands, the growth is soft and watery, whereas if potash is abundant and FERTILIZERS 15 the nitrogen supply less, the growth is hard and firm. As illustration : note the strength of chap- arral wood, compared with marsh land growth. Nitrogen is deficient (comparatively) where the chap- arral grows and the mineral or soil derived elements, including potassium, relatively abundant. In a word, potassium gives starch or stiffness to the plant. Young peppers, acacias and eucalyptus trees bend frequently to the ground because their roots are in the surface soil, feeding on the excess of nitrogen and water. Older trees with deeper roots have not this tendency. (71). Sulphur, iron, calcium and silicon also perform special parts in the building of plant tissue, but a discussion of these would extend our subject unneces- sarily; Thej- are not "essential" plant foods. (23). PHYSICAL CONDITIONS. 20. In California the mechanical or physical con- dition of the soil is of greater importance than the chemical composition. Especially is this true of cit- rus culture, where irrigation and cultivation are so frequent and thorough. The first sign of trouble is usually a slight yellow color of the foliage and is usually traceable to loss of humus and its conse- quent nitrogen. Yet the cause may be due to the roots entering a "hard pan" or coarse gravelly strata, less favorable to growth. (99). In any event the soil's mechanical condition should be known to a depth of at least five feet, and deeper if possible. The loss of humus so changes the soil's condition that the trees cannot derive the benefit of the water, the cultivation or the labor gives to it, and the first sign is the loss of the healthy green color. 16 FERTILIZERS Applications of nitrate are helpful but not lasting unless applied in organic forms, capable of making humus. (86) (96). DRAINAGE. 21. Citrus soils must be well drained. The top soil may be free from gravel for a considerable depth as long as it does not hold free water. The "mesa" or " bench " soils of California, usually situated near the foot hills, are ideal in this regard. Figure 2 is a photograph of a stream bank, running through a "mesa." The top soil, free from rock, is here about 5 feet deep, below which there is excellent drainage. HARD PANS. 22. Occasionally the best situation and soil for fruit culture is underlaid at a few feet with an im- pervious strata, so that orchards soon show lack of vigor. These "hard pans" may be at the very sur- face or at any depth below. Blasting with powder or dynamite to break up the fixed condition is effec- tive, but must be repeated from time to time. Per- haps the best remedy where water is sufficient, is to prepare it long before planting trees, by raising a one or two year old stand of alfalfa, the roots of which penetrate hard soils to a considerable depth. Though the orchard is already established, alfalfa might be grown in alternate spaces between the tree rows for two years, then ploughed under and the remaining spaces planted for the next two years. " Hard pans" are usually deficient in nitrogen, but may be well supplied with the other plant foods, and especially with lime and iron. The latter gives a very noticeable deep red tint to the orange. FIGURE 2 FERTILIZERS 1 7 ESSENTIAL PLANT FOOD. 23. Each of the three plant foods, nitrogen, phos- phoric acid and potash, are called essential ingredi- ents in fertilizers, as they are the elements first exhausted from the soil by plants. There are eleven other elements just as essential to perfect plant growth as these three, but the soil never becomes depleted of them, and it is not necessary to supply them, except in rare cases. Sometimes lime is sup- plied to the soil, though not regularly, to set free nitrogen, phosphoric acid and potash, when they are known to be in the soil in insoluble condition and large amounts. But, as lime adds no necessary ingredient, its continued use alone will exhaust a soil. If a soil is known to lack iron, this may be added to make green foliage and to deepen the color of oranges. If a soil becomes unproductive under conditions of good tillage and water, it is usually because one or more of the essential plant foods has become ex- hausted. Hence commercial fertilizers have come to be composed of various amounts and forms of nitro- gen, phosphoric acid and potash. Commercial fer- tilizers are simply concentrated forms of plant food. A good top soil contains every element essential to plant growth and is a fertilizer, but it is not suffi- ciently concentrated to pay for handling and trans- portation. 24. Each of the three plant foods, nitrogen, phos- phoric acid and potash, have their respective market values for each 1 per cent., or unit, of 20 pounds to the ton. If a ton of fertilizer contains 3 per cent, of an element that means 60 pounds. The purchaser 18 FERTILIZERS will have to know in addition to the amount, the market value and the source of the nitrogen, phos- phoric acid and potash, before he can determine the value of a ton of certain analysis. The source is very important, because the most available forms have the highest market value. Without this know- ledge, a certain brand may sell for $40 a ton and another worth only one-half its value ($20 per ton) may sell more readily for $38. 25. Each of the three essential plant foods has its special part to do in the building of the plant. One cannot do the work of the other. As an illus- tration: Nitrogen in the absence of potash may produce a luxuriant and rapid growth but it will be weak, and broken down by the first wind ; add potash and that same succulent, weak growth will be matured and have strength enough to carry its load of fruit. Potash alone will not produce the growth, but will mature it. Both nitrogen and potash have manv other functions to perform. (69), (71). Phosphoric acid, or phosphorus, must be present in order that the plant may assimilate its nitrogen. The process (osmosis) by which nutrients pass through the plant from cell to cell is facilitated by the presence of phosphoric acid. Phosphorus is nec- essary for the seed's embryo development and for the formation of chlorophyl (the green coloring matter of plants). (70). Thus, while the essential plant foods each have many independent functions to perform, they are mutually dependent upon each other, and mutually helpful in the building of the plant tissue. FERTILIZERS 19 The condition in the soil may be such that the purchase of only one fertilizing element is necessary, and since the source of nitrogen and phosphoric acid and their functions are so many and varied, the question, "What fertilizer to use," and "How to purchase it most economically," is of vital interest to the farmer and one difficult to solve. SOURCE OF FERTILIZERS. THE SOURCE OF NITROGEN. 26. Nitrogen may be obtained from these sources : Air, ammonia, nitrates, and animal matter. In certain forms of animal matter, such as hoofs, horns, coarse bone, leather and wool waste, the nitrogen becomes available too slowly to be of much value. But as green manure, ammonia, nitrates, blood, fine bone, tankage, or blood and bone, fish and finely ground and screened guano, the nitrogen is in good form and soon becomes available. 27. As these forms require different lengths of time to become available, judgment must be used in their application. Nitrate of soda and sulphate of ammonia dissolve almost immediately in water, so the full amount of a year's supply should not be applied at once, as some will be sure to be lost in waste water. Blood and bone, as a source of nitro- gen and phosphoric acid, would be a better combi- nation than nitrate and bone. Blood and fish re- quire more time to become available than nitrates, and bone, a longer time than blood. (43) 20 FERTILIZERS The most valuable sources of organic nitrogen, from the standpoints of uniformity in composition, richness in the constituent, and availability, are dried blood, dried meat, and concentrated tankage, fish and animal, which are produced in large quantities in slaughter houses and fish canneries. 28. The most concentrated form of nitrogen is ammonium sulphate, containing about 19% or 24% of ammonia. Nitrate of soda contains as high as 16% nitrogen, blood 14%, hoof and horn meal, 14%, slaughter house tankage from 5% to 10%, raw bone B^%, bat guano 3% to 20%, sea fowl guano 12%. There are numerous other sources of nitrogen, but the above are those most generally used. The contents as given are in terms of nitrogen and approximately the maximum. SoUtit 7 \ N&u*^ -w *y- • \ MZmwowa jfc>a.ca.r cents per pound. Only one should be included in the estimate. And so with the terms bone phosphate and phos- phoric acid. The phosphoric acid comes from the bone phosphate. For example, it takes 30% of bone phosphate (sometimes called 'bone phosphate of lime') to make 13.74% of phosphoric acid. When both terms are employed by the manufacturer the words "equal to" should be used thus: "Bone phosphate of lime, 30%, equal to phosphoric acid, 13.74%," which means that the manufacturer used 600 pounds of bone phosphate or bone — 30% of the ton— to obtain 13.74% of phosphoric acid. Multiply the percentage of bone phosphate by .458 and the result will be the equivalent in phos- phoric acid thus: 30% bone phosphate of lime X. 458=13. 74% phosphoric acid. In estimating the value, for comparison, of a ton in dollars and cents, phosphoric acid from fine bone is worth about 5^ cents per pound, while its equiva- lent in terms of bone phosphate is worth only 2V£ cents per pound. Only one should be included in the estimate. Where the "soluble," the "reverted," and the "insoluble," and the "total" phosphoric acid are all given, it is understood that the "total" is made up of the first three mentioned. 46 FERTILIZERS The sulphate and muriate of potash will analyze in round numbers about 50% actual potash (some- times expressed as K2O). In other words it takes two pounds of sulphate or muriate of potash to make one pound of actual potash (K2O). When an analysis states : "Sulphate of potash 8%, actual potash 4%," it means simply that there is only 4% of actual potash in the ton, or 80 pounds, and that the manufacturers used 8% or 160 pounds of sul- phate of potash to get it. The actual potash is worth about six cents per pound, while the sulphate is worth only three cents per pound. When both terms are used in stating the analysis, only one of them should be included in the estimate of the value of a ton. COMMERCIAL VS. AGRICULTURAL VALUE. 67. Farmers frequently confound the agricultural and commercial value of a fertilizer. If one is high it does not necessarily imply that the other must be. The commercial value of any commodity is its market price, its purchase price, and depends entirely upon "supply and demand." The agricultural value of a fertilizer is its ability to improve the fertility of the soil and the condition of the crop in question. As an illustration, suppose a steady, long-lived food were wanted for some perennials as an orchard, blood would answer the purpose while nitrate of soda would be soon exhausted or lost by leaching. Now, if the price of both nitrate and blood is about the same, the agricultural value of blood is far greater. If a quickly acting manure was wanted, the nitrate of soda would have the higher agricul- tural value. FERTILIZERS 47 Again, if phosphoric acid was not needed for a particular soil and crop, it would then have no agri- cultural value in that case, but would still have a market, or commercial value. In the selection of a fertilizer, the agricultural value should be considered first and the commercial value second. Good results are of first importance and depends on the agricultural value. THE USE OF FERTILIZERS. 68. In order to use fertilizers intelligently, it is necessary to know the specific action of the three plant foods; nitrogen, phosphoric acid, and potash, their sources, and when and how to apply them. The few experiments which have been made with various fertilizers on citrus trees confirm the same general principles that hold with reference to other crops. They will be briefly stated. EFFECT OF NITROGEN. 69. The presence of available nitrogen is shown by a dark, healthy, green color of leaves and stems. Growth is vigorous. The feeding power of the plant is increased. If an excess of nitrogen is available at the time of flowering, and the supply of phosphoric acid insufficient, the bud and bloom and fruit will be imperfect and the total amount of fruit lessened. The fruit will then be rough and thick-skinned. Constant use of stable manure, without the addition of phosphoric acid, will produce thick-rind fruit. The size of fruit may be increased by nitrogen. A 48 FERTILIZERS lack of nitrogen is shown by yellow trees and small growth, or lack of vigor. Nitrogen will not give its best effect unless phosphoric acid and potash are present. EFFECT OF PHOSPHORIC ACID. 70. Phosphoric acid helps a plant to assimilate other plant foods. It is also essential to the final maturity of the plant or its seed production, and hastens this maturity, if abundant and available at blossoming time. Although the navel orange con- tains no seed, phosphoric acid is as essential as though it did. What usually thus goes into seed is needed elsewhere in the development of the fruit. If maturity is hastened by the presence of an abundance of available phosphoric acid at the time of blossom, the early ripening of the orange can be likewise effected, though plant food effects are directly dependent upon culture and water. Phosphoric acid will not give its best effect unless there is some nitrogen present. Plants well supplied with phosphorus, vegetate faster and are earlier. If an over abundance of nitrogen is making fruit rough or "puffy," phosphoric acid will help to correct this. Its tendency is to make thin-skinned, smooth fruit. EFFECT OF POTASH. 71. Potash is necessary to the full development of the wood of the tree. If potash is wanting, the wood not only will not mature, but is subject to frost and disease ; neither can immature wood carry much fruit. Potash aids in the formation and trans- fer of starch, first to the leaves and from there to the flesh of the fruit, which would be imperfect other- FERTILIZERS 49 wise. The best authorities agree that potash in- creases the sweetness of fruit and their shipping quality. (19). Plants, undoubtedly, begin their growth in the spring on the food that was stored in their tissues the previous fall. Potash is largely the source of this stored food, and is consequently necessary to the full growth and health of the tree. It is generally admitted, however, that applica- tions of potash are unnecessary in most California soils. Many cases are reported in which heavy applications of wood ashes gave no appreciable results. If the land in question has been continuously cropped many years, as in a fifteen or twenty years' old orchard, the potash question should be carefully investigated. 72. Besides its effect on the plant as potash or potassium, increasing the starches and sugars, the use of potash salts has another indirect fertilizing effect similar to that of lime and common salt, by causing the soil to yield more quickly, its natural and other plant foods. Potash salts while neutral, may increase the alkalinity of the soil and thus foster and encourage the work of nitrifying and other bacteria which transform decayed organic matter into useful forms. Carbon is one of the result- ant products, so that the carbonic acid which soil moisture carries, may be increased thus making it a better solvent of many other plant foods. This increased alkalinity of the soil may therefore increase the formation of the nitrates and more vigorous growth will result. Potassium as such, did not pro- duce this result, which was due rather to the added 50 FERTILIZERS alkaline effect of the potash salt. Lime carbonate or gypsum or common table salt might have produced the same effect. GENERAL PRINCIPLES. 73. In a general way, both phosphoric acid and potash influence the quality and fineness of the fruit, while nitrogen produces the vegetable tissue, such as the skin and pulp of fruit, and leaves and bark of trees. The juice and seed and smoothness and the number of the fruits, and earliness, can be increased by phosphoric acid and potash . The size and coarse- ness and large growth and late maturity can be secured by the excessive use of nitrogen. These effects are noticeable only when there is an excess of one element and a deficiency of the others. AVOIDING PURCHASES OF UNNECESSARY FERTILIZERS. 74. Knowing the specific effect of the three essen- tial plant foods, as just stated, and by observing the condition of an orchard, a grower may frequently avoid the purchase of unnecessary plant food. Bottom lands are usually rich in nitrogen. Sandy soils are apt to lack potash. Clay soils usually con- tain much potash, etc. Coarse, thick-rind fruit, with deep green color of leaves and a too vigorous growth may indicate that nitrogen could profitably be omitted one season, or used very lightly. An over abundance of smooth fruit on yellow trees of slow growth may indicate an excess of phosphoric acid for the nitrogen present, or a lack of nitrogen. Iron is as essential as nitrogen to green leaves and stems, so yellow foliage may, in rare cases, be caused by the absence of iron as well as nitrogen. The amount of iron necessary for green foliage is so small, that lack FERTILIZERS 51 of nitrogen is usually the cause of yellow color in citrus orchards. A careful record of previous applications, namely : The amount and analysis of the fertilizer, time of application, and its effects on growth and crop will be a guide to selection. TIME TO APPLY FERTILIZERS. 75. In the book of nature we read that growth is dormant for some months preceeding the blossom and fruit setting period. This is naturally the time of most moisture in soils, which with root acids and fermentation, are rendering available the unavail- able plant foods natural to the soil. So, when the important time of blossom comes, the plants have their greatest store of available plant food to draw upon, so that fertilizers should be applied long enough before the blossom time to become avail- able. 76. Nitrate of soda requires the least time. Blood requires more time than nitrate, and raw bone more time than blood. Coarse bone, and hoof and horn meal, are slowest in their action. Acidulated phos- phate acts more quickly than any other form (that is the soluble portion.) Steamed, fine ground bone, used with some ammoniate, is next in order, while fatty, raw bone takes still more time to decompose. (46-48). Many apply a part of the fertilizer in early sum- mer. This is intended to feed the latter growth of tree and crop. It is a practice that undoubtedly gives better results and is gaining in favor. 77. Acidulated forms should always be applied just before an irrigation or rain, for then the water 52 FERTILIZERS will carry the soluble portion to the deepest roots, wherever, in fact water can go. There, reversion to insolubility may and probably does occur in a few days, but the phosphoric acid is where the roots can act on it directly. (8) (35). Nitrate of soda should not be applied in late fall or winter months while growth is dormant, as it would probably be leached away before the tree could take it up. Organic forms should be applied in Janu- ary or February. AMOUNT TO APPLY. 78. The quantity of fertilizer that should be used varies with the conditions. It depends upon : 1. The percentage richness of the fertilizer. 2. Record of past experience. 3. Natural richness of soil. 4. Age and number of trees per acre. 5. Kind of tree or crop. One popular way of estimating the amount to use is to say one pound of high grade fertilizer to each year of age of the tree. This, while very inaccurate, gives good results, but the practice of citrus culture has demonstrated the wisdom of using considerably more than this amount, probably two pounds for each year of age of citrus trees will be fully war- ranted in most cases. This is particularly true of trees over twelve and fifteen years old. If the fertilizer is low grade, the amount used should be increased. If trees have been topped for budding or very severely pruned, the amount may be reduced accor- dingly. FERTILIZERS 53 METHODS OF APPLICATION. 79. The best method of application is undoubt- edly by drill, on account of its labor saving and uniformity. Though not over five inches deep, the drill covers the fertilizer, which can be placed deeper by subsequent plowing. The use of drill obviates the unpleasantness of applying in any winds which may prevail. No hand process is so uniform or inexpensive, though some other methods place the fertilizer deeper. It is well worth the extra cost to hire a hand to follow each plow furrow and place the fertilizer that depth. STABLE MANURE. 80. An average analysis of one ton of horse manure would be : Nitrogen— 0.50% or 10 lbs. of a ton at 20c $2.00 Phosphoric acid — 0.25% or 5 lbs. of a ton at 6c. .30 Potash— 0.40% or 9.6 lbs. of a ton at 6c 58 $2.88 The commercial value of the plant food is then about $2.88 per ton. Barn yard manure when cared for properly, is a most profitable form of fertilizer, because of its humic and mulch value. It is a bi- product of every ranch, costs nothing, and is worth about $2.88 per ton for the actual plant food con- tained. In dry countries it has a still greater value in its moisture saving properties. As a source of humus it is worth considerably more than its plant food value. 81. The more decomposed the manure, the more available is its plant food. If, however, decomposi- tion is too rapid, the nitrogen escapes in the air as ammonia, and humus-forming matter is destroyed. 54 FERTILIZERS High temperatures produce rapid decomposition, especially in a loose heap, so that the rate of decay maybe regulated by compacting the heap and sprink- ling with water to exclude the air and reduce the temperature. If compacted too tightly, decomposi- tion may be too slow. Moderate fermentation is the object desired. Loss of nitrogen, as ammonia, may be detected by the strong odor arising, from the heap. If it is desired to obtain the benefits of the plant food in manure quickly, it should be stored under cover to prevent loss by leaching, and the tempera- ture kept down by frequent wetting, and air ex- cluded by settling the heap : decomposition may thus take place with a minimum loss of ammonia. If from one to two pounds of either gypsum, or sul- phate of potash be sprinkled on the heap each day as it accumulates from one or two animals, the am- monia is converted to the sulphate form and thus prevented from escaping. The gypsum must be moist for this use to be effective. If, however, it is not desired to get the benefits of plant food quickly, the manure had better be applied fresh and incorporated with the soil at once. Decom- position may be slower in such cases, but loss of ammonia is surely prevented and a much better mulch obtained. This is the most practical method. GREEN MANURING. 82. The object of sowing the leguminous, or pod- bearing plants is chiefly four-fold. 1. For humus, which is always necessary for any form of crop because of its various functions in the soil, such as : (a) nitrification ; (b) Rendering insol- uble forms of plant food available by the process of FERTILIZERS 55 decay, (29) ; (c) Increasing the moisture holding power and friability of the soil. (90.) 2. To obtain the nitrogen which they gather during their growth. (30). 3. To set free unavailable plant foods by the direct action of their roots. (Insoluble substances are coroded, and dissolved and taken up into the plant tissue and later become available as the plant decays.) 4. To prevent soil washing and leaching by win- ter rains. 83. The common vetch (Vicia Sativa) is at pres- ent the most popular legume for the California orch- ardist. Field peas, some clovers, and other varieties of vetch are also used. Barley and other non legu- minous plants have not the same nitrogen gather- ing power but are beneficial as far as their roots set free unavailable forms of potash and phosphoric acid. The volunteer non-leguminous plants and weeds such as alfilerea mallow, foxtail and others, are per- haps as beneficial as legumes plants for their humus value and root petetration and while it is not cer- tainty known just now how much nitrogen may be added by various legumes it is probably safe to assume that they add some and for this reason are preferred to the non-leguminous plants. COVER CROPS AND WATER. 84. It is well known that the winter cover crops use up a good portion of the rain that falls so that comparatively the clean culture orchards begin the dry season with more moisture in the ground. While this loss is usually more than compensated for by 56 FERTILIZERS the many advantages of the cover crop already cited there may be special situations where the water is all necessary to the orchard. If the water right were limited by the capacity of the ditch or if the season's rainfall were too short to risk the loss of water necessary to a cover crop, straw or dam- aged hay could be hauled and spread and plowed under as a fair substitute. Any amount of humus could be added in this way and all of the rainfall con- served for the summer months. SUMMER COVER CROPS. 85. It is difficult to maintain the supply of humus material under conditions of constant irrigation and cultivation. Cover crops have been raised in sum- mer as well as in winter in a few instances. Horse beans and cow peas have been used for the purpose. They are planted in May or June and turned under in August, and while the results are undoubtedly beneficial the extra water necessar}' will prevent the practice from becoming general. The United States Government has found by ex- periment in California orchards, several legumes that promise a greater tonage of green matter, under equal conditions, than the present Oregon or com- mon vetch so generally used. These include two species of Vicia; one pea, and one bean. So that this phase of agriculture will no doubt be improved and modified from time to time. The green manure wanted by orange growers is one that will grow quickly as California winters are short and dry, and growers cannot afford to let the ground rest undisturbed very long. FERTILIZERS 57 HUMUS FERTILIZERS-NECESSITY OF ORGANIC MATTER. 86. Humus is decayed organic matter. It is neces- sary for fertility, because all the nitrogen in soils comes from either an animal or vegetable source. (Very minute quantities are absorbed from the air as ammonia and as nitrogen). The nitrates come from humus. They are water soluble and can be taken up by the roots. Thus the plant gets its nitrogen. (15) (29) All fertile soils are rich in organic matter. The ex- ceeding richness of new lands is due to the humus deposited by succeeding crops for generations. This is true of both the high mesa and the valley land. It is possible to use some chemical form of nitrogen and raise a plant, but it is expensive, requires close watching and is not practical. The nitrogen from organic fertilizers is yielded to the plant gradually, with greater certainty, and is more lasting. 87. Organic manures, whether of blood and bone, or stable manure, or green cover crops, not only furnish nitrogen to plant life, but their decay gen- erates several well known acids, notably carbonic, which combine with the soil moisture and dissolve other forms of plant food. Without these acids, phosphorus, potash and other necessary elements would not be so available to the plant. Direct root and water action would then have to do the work alone, and the plant would not thrive so well. Hu- mus influences the availability of the phosphoric acid and potash and converts them into forms more readily utilized by the plant. (49-50). 58 FERTILIZERS 88. Organic fertilizers lighten soils. Their decay leaves the soil open and porous. More oxygen is thus admitted, which gives more life to the micro- organisms, which, after all, are the cause of all fer- tility. Better cultivation is possible in such soils. Light, porous soils are more retentive of moisture. Thus, organic matter literally builds up a soil. It increases its depth. A "worn-out" soil is simply a soil devoid of humus. It is lifeless. Liberal applica- tions of organic matter restore it and change it from a tax to an income. 89. Humus forming-materials are, therefore, necessary to successful and practical farming. The best results from inorganic fertilizers, such as rock and acid phosphates, Thomas slag and sulphate of potash, are obtained when they are used with ma- nure, or blood, or blood and bone, or a green cover crop turned under. 90. "Humus is not only the principal source of nitrogen in soils, but it influences to a marked ex- tent the available potash and phosphoric acid. Humus forming materials, like green manures and yard manure, have the power, when they decompose in the soil, of combining with the potash and phos- phoric acid of the soil and thus converting them into forms which are readily utilized by the plants. "(82). CULTIVATION AND FERTILIZERS. 91. Cultivation increases the availability of fer- tilizers by aiding nitrification and by saving soil moisture. All organic forms must first decay and then be turned into nitrates (nitrification), and FERTILIZERS 59 other salts before water can carry their elements to the roots of plants. (29). The decomposed matter (humus) is attacked by nitrifying bacteria and these require oxygen for their work. Cultivation increases this supply of oxygen so that nitrification proceeds faster, and better growth results. The more frequent and deep the cultivation, the better the nitrifying bacteria can work. The size of fruit can be increased in this way, or a short season made equal to a long one. Cultivation therefore uses up humus very rapidly so that the supply must be frequently renewed. The extra growth and yield are probably proportional to the supply of humus and frequency of cultivation. 92. This principle of aiding nitrification applies to all forms of animal and vegetable fertilizers such as yard manure, blood, raw bone, guano, tankage, and peas and clover, planted for their fertilizing value when ploughed under. Frequent, deep cultivation increases the supply of water in soils. Several well-known acids, result- ing from decomposition, unite with soil moisture and dissolve what ordinary water will not. Insol- uble forms of fertilizers, such as phosphate of lime and silicate of potash, are probably thus made available to the plant. 93. Moist soils swell and are more permeable. Roots can develop faster in them, and the fertilizers, applied to the top, six inches, as they gradually dis- solve, can be carried more easily and deeply, increas- ing the feeding area of the roots and the develop- ment of the plant. Frequent and through cultivation, helps and multiplies these beneficial effects of soil moisture. 60 FERTILIZERS IRRIGATION AND FERTILIZERS. 94. Plants can take up food, only when it is pro- vided in solution. The food may be dissolved by water, or by direct root action, or by the process of fermentation, which is almost constant in all soils. In either case water is essential, and the common carrier, and the way in which it is used, seriously effects the results of fertilization. Especially is this true because the top foot of soil contains the most valuable fertilizing ingredients. There are three kinds of water in soils : free water which moves by gravity ; hygroscopic water, detect- able only by laboratory methods even in the dryest earth, and capillary water, which moves by the power of attraction between particles of matter. This capillary water is what plants feed and depend upon mainly. It travels up and down freely with very little motion, sideways, carrying with it the soluble fertilizers. 95. It is useless to apply fertilizers on dry ground that is not dampened by irrigating water, as for instance ; far under very old trees or on the midway spaces in young orchards where furrows are not made. As moisture evaporates at the surface, it is con- stantly supplied from below by the capillary move- ment. The dissolved fertilizers contained, remain at the surface from which the water evaporates ; hence they accumulate so that top soils are always the richest. The next rain or irrigation carries the plant food down only to rise again as evaporation pro- gresses at the surface. There is thus an oscillation of water containing many kinds of plant food, up and down many times a year. FERTILIZERS 61 96. Certain forms of fertilizers, such as the ni- trates (both soda and potash) ammonium sulphate, the sulphate of potash, and the acid and super-phos- phates are easily carried by water. If applied just previous to an irrigation they go to the deepest roots, or wherever water can go. If there is any waste water a part of them is lost. If the grade from the flume is very steep for fifty feet or more, the trees in that space will be the first to turn yellow, although they are nearest the flume and receive the most water. The nitrates have been washed to lower levels. Manure or straw should be used in such places so that the water will move more slowly and the nitrates retained where they belong. On account of the solubility of many forms of plant food, irrigation water should be handled very carefully. Do not turn a heavy head of water into a furrow until after the furrow is soaked a little and the fine earth compacted. This will lessen washing. The ideal movement of water is up and down, with as little movement on the surface as possible. In this way the rich top soil with its humus and fer- tilizers will be retained where it belongs. VALUE OF SOIL ANALYSIS. 97. Soil anatyses are valuable for determining in a general way the needs of a crop. The greater the number of samples examined, the more accurate will be the information obtained. Very little can be con- cluded from one sample. Taken in connection with the appearance of trees and vegetation raised on the soil, many a useless expenditure for fertilizing ingre- dients may thus be avoided. 62 FERTILIZERS If samples of soil be taken according to the direc- tions of the State Experiment Station the results may be relied upon as indicating that soil's capacity for various crops. This information, with the owner's knowledge of previous treatment, together with the appearance of the vegetation and growth gives a pretty thorough diagnosis. Each of these sources of information acts as a check or supple- ments the other two. 98. Soil analysis should be interpreted by an ex- pert for where y^ of 1 % would be considered a suffic- iency of some element, it would be regarded as a deficiency of other elements. A soil containing % of 1% humus is lacking in that substance, while that amount of potash or lime would be considered ample for fertility. (100). Again, soil analyses may reveal the presence of some poison, such as carbonate of soda, or chlorine, in the midst of otherwise fertile conditions, An ex- cess of either acid or alkali can likewise be deter- mined. Plant food may be present in abundance and yet the results be unsatisfactory on account of poor cultural conditions, or lack of humus. This, also, soil analysis would reveal. Whenever there is uncertainty about the needs of crops or orchard, soil analysis should always be taken. One element, only may be lacking and thus discovered, and the purchase of the element unneces- sary be avoided. The California State Experiment Station has advised farmers that sufficient potash is present in nearly all California soils. General experi- ence has confirmed this statement, thus saving the farmers many dollars annually. FERTILIZERS 63 99. The mechanical analysis of soils is always important. Most California soils are sedimentary and composed of irregular strata varying in thick- ness from a few inches to many feet. They may be impenetra table and poorly drained, or too open and coarse to hold the requisite moisture. The subsoil conditions should be known. (20-21-22). 100. The following table is compiled mainly from the records of the California State Experiment Sta- tion and from Dr. Hilgard's book, "Soil," which state quite positively that when the chemical deter- mination of certain elements in soils run below a certain amount that soil is quite sure to be unpro- ductive. These figures are the result of a large num- ber of analyses representing years of work. ADEQUATE PLANT FOOD. RICH ADEQUATE INADEQUATE PER CENT. PER CENT. PER CENT. Humus in soil 2.00 1.00 0.85 Nitrogen in humus 9.00 4.00 2.00 Lime 1.50 1.00 0.40 Phosphoric acid 0.20 0.10 0.05 Potash (K20) 1.00 0.45 0.25 These figures will vary for different crops. Ade- quacy for one kind of crop might be inadequate for another. But they are averages for a large number of determinations and very suggestive. It has been well established also that when the per cent, of lime is high, much smaller amounts of the other plant foods will suffice. 64 FERTILIZERS FERTILIZING VALUE OF STRAW, STABLE MANURE, ORANGE CULLS, AND CERTAIN LEGUMES, f 101. N. P. A. Pot.* JPea vine hay 3.00 $12.00 $ Vetch hay 2.55 10.20 Burr clover hay 2.68 10.72 Alfalfa hay 2.19 1.51 1.68 11.37 Wheat straw 0.59 0.12 0.51 3.12 Stable manure 0.50 0.25 0.50 2.87 Orange culls 0.18 0.12 0.21 1.10 •(Nitrogen @ $4.00 per unit. Phos. acid @ $1.00 per unit and potash @ $1.25 per unit.) fThe value of the above materials for humus is probably equal to, or greater than their fertility value as judged by the results obtained from their use. $It is assumed in the table that the pea, vetch and burr clover were raised as a cover catch crop in the orchard, and that this nitrogen is all gain, which fact is not yet established beyond doubt. Their phosphoric acid and potash are not reported, as what they take of these from the soil is returned with them. INDEX. Acidulated Phosphates 23 Adequate plant food 63 Agricultural value 46 Alfalfa, fertilizing value 64 Analysis adding to 100 per cent 43 Analysis of fertilizer. How to understand 44 Analysis of soil 61 Applying fertilizers, Time for 51 Applying fertilizers, Amount 52 Applying fertilizers, Method 53 Applying fertilizers deeply 9 Availability 28 Availability, Order of 29 Basic slag 25 Bone 25 Burr clover, fertilizing value 64 Canadian peas, fertilizing value 64 Commercial value 46 Clover crops and water 55 Culls, fertilizing value 64 Cultivation, relation to fertilizers 58 Drainage of soils 16 Economical form of fertilizers 38 Effects of plant foods 50 Essential plant food 17 Example of fertilizer worth $6.50 per ton 39 Example of fertilizer worth $41.10 per ton 39 Fertilizers, purchase 32 Fertilizers, source 19 Fertilizers, use 47 General principles, effect of fertilizers 50 Green manure 54 High grade fertilizer, example 40 INDEX. Home mixtures 42 Humus (organic matter) 57 Insolubility, desirable 31 Irrigation, relation to fertilizers 60 Lower grade fertilizers, example 40 Manure, green 54 Manure, stable 53 Manure, fertilizing value 64 Most economical form 88 Nitrification 21 Nitrogen, cost of 37 Nitrogen, effect of 47 Nitrogen, from air 21 Nitrogen, sources of 19 Nitrogen from organic sources 22 Nitrogen cycle 20 Nitrate of soda and carbonates 22 Orange culls 64 Organic matter (humus) 57 Peas, green manure 54 Phosphate guanos 26 Phosphoric acid, cheapest form 26 Phosphoric acid, cost of 37 Phosphoric acid, effect of 48 Phosphoric acid, sources of 23 Plants, general 5 Plant food, amount necessary 63 Plant food 11 Plant food "essential" 17 Plant food, air derived II Plant food, soil derived 11 Plant food, definition 17 Potash, effect of 48 INDEX. Potash, cost of 37 Potash, sources of 27 Purchasing, general principles 39 Purchase of fertilizer 32 Roots 8 Reversion of phosphates 24 "Simples" 42 Soil analysis, value of 61 Soils, composition of 11 Soils, fix phosphorus 24 Soils, drainage of 16 Soils, physical condition 15 Source of fertilizers 19 Solubility in different soils 30 Stable manure 53 Steamed bone 25 Straw, fertilizing value 64 Summer cover crop 56 Thomas phosphate slag 25 Unnecessary fertilizers, avoiding purchase 50 Use of fertilizers 47 Vetch, common, fertilizing value 64 Vetch, green manure 54 UNIVERSITY OF CALIFORNIA LIBRARY Los Angeles This book is DUE on the last date stamped below. OK 1 4 1954 JUNIUS*"! Form L9-25m-9,*47(A5618)444 s 633 S61i3f 1911