Fertilizing for profit

Introduction

THE SOUTH spends $50,000,000 a year for commercial fertilizers, and the amount is steadily increasing — increasing proportionately faster, in fact, tlian is the average crop production per acre. In other words, Southern farmers spend $50,000,000 a year for plant foods and then fail to improve their soils. This is true, not because commercial fertilizers are not good to use, but because they are used extravagantly and unwisely.

If all this great sum were spent for the right sort of fertilizers — those needed by the crops on the particular lands where they are grown — and if due attention were paid to the physical condition of the soil — to the humus supply, to drainage, to tilth and texture, — the lands of the South would grow richer and richer with each succeeding year, and instead of thousands of "worn-out" and abandoned fields, gullied, galled, overgrown with briers and bushes, there would be broad acres teeming with crops double and treble those nov/ grown by the average farmer.

It is with the hope that they may point the way to a more judicious and profitable use of fertilizers that the following chapters have been written. While attention is called again and again to the waste of much of the money now spent for fertilizers, and while the fact that commercial fertilizers alone can not maintain soil fertility is repeatedly stressed, there has been no suggestion that commercial fertilizers should not be used. The

4 INTRODUCTION.

writer believes In commercial fertilizers, and that their use will increase; he also believes that it is sheer folly to use them on land that is not well drained or that is hard and dry because it lacks vegetable matter. Nor does he believe that it is any part of wisdom for a farmer to buy fertilizers without some knowledge of what the analysis on the bag means, of just what effect the particular combination he is buying may be expected to have upon plant growth, and without some idea as to what elements of plant food the crop is likely to need most on the land where it is planted.

It is believed that the man who is willing to read these pages carefully, and to think as he reads, will find some help in working out all these problems, and will be able to get a larger return from the fertilizers he uses. No attempt is made to tell any man just what fertilizer he should use or how much, since that is a manifest impossibility; but an effort has been made to make the fundamental facts underlying all fertilization so plain that any one can understand them, and to show the ordinary farmer, busy, and without any special learning along this line, how he can apply them on his own farm so as to make better crops and build up his soil.

Raleigh, N. C. E. E. MILLER.

Contents

CHAPTER PAGE

I. What Fertilizers Are and Why Used.

Different Kinds of Fertilizers— Three Plant Foods We Buy — Four Facts to Remember 9

Index To Appendix

PAGE

Plant Food in Tjrpical Soils 95

What Crops Take From the Soil 96

What Some Hay Crops Took Away 98

Fertilizing Materials in Feeding Stuffs 99

Analyses of Fertilizing Materials 101

Value of Manure Produced by Live Stock 102

Composition of Farm Manures 102

Ten Sample Mixtures That Farmers Can Make 104

Chapter I. What Fertilizers Are And Why Used

FERTILIZERS, as they will be spoken of in these chapters, include any substance containing available plant food, which may be applied to the soil to promote the growth of the crops.

This is one thing which many farmers seem to fail utterly to understand: that fertilizers are food for plants, not medicine for the soil, nor any sort of magic preparation to increase the crops in some mysterious manner. The man who applies nitrate of soda or acid phosphate or stable manure or any sort of "guano" to his crops, does for them just what he does for his live stock when he puts oats into his horses' feed boxes or swill into his pigs' troughs — he feeds them.

Plants get from the air two foods — carbon and oxygen — and from the soil about a dozen others which are necessary to their development. Of these foods, however, only three — nitrogen, phosphoric acid and potash, are at all likely to be lacking in the soil. These three elements, then, are the ones we apply in fertilizers. Sometimes, it is true, lime is supplied, but most soils contain all the lime needed for plant food, and it is generally used for its effect upon the texture of the soil or to sweeten it when sour.

THE DIFFERENT KINDS OF FERTILIZERS.

With this definition of fertilizers in mind, it may be well next to consider the kinds of fertilizers or manures commonly used:

1. "Green manures" are crops grown to be returned to the soil; and they add humus only, except in the case of the legumes, such as the clovers, cowpeas, soy beans, the vetches, etc. These plants have the power, by the aid of certain bacteria, to take from the air much of the nitrogen needed for their growth and thus add to the nitrogen supply as well as to the stores of humus in the soil. They are discussed more fully in Chapters 14 and 15.

2. Stable manures are valuable both for the humus they add to the soil, and for the plant food they carry. While the amounts of plant food they contain are very small compared with that found in most commercial fertilizers, stable manures, by aiding bacterial activity and chemical action in the soil, also aid in making more available some of the plant food it already contains and are thus beneficial in three ways.

3. "Commercial fertilizers," is the broad term which includes all the substances containing large quantities of plant food that are bought by farmers for their crops. The three elements of plant food they contain are nitrogen, phosphoric acid and potash; and a fertilizer may contain one or all of these. Most fertilizers as sold are mixtures of substances containing these elements in various proportions. Thus the ordinary "8 — 2 — 2" fertilizer is likely to be made up of acid phosphate, kainit, cottonseed meal, possibly nitrate of soda, and a "filler" of some kind. The same thing is true of practically all "complete" fertilizers — that is fertilizers containing all three of these essential foods. Commer-

WHAT FERTILIZERS ARE AND WHY USED. 11

cial fertilizers are generally bought solely for the available plant food they contain.

THE THREE PLANT FOODS WE BUY,

These three plant foods, which we apply in fertilizers, have each a special function in the growth and development of the plant. While all are necessary to the proper development of the plant, a deficiency in the supply of either is noted by certain characteristic signs. Thus where there is not enough nitrogen, the plants are likely to make a scanty growth of stalk and foliage, to be yellowish in color instead of dark green, and to be generally lacking in vigor and healthiness. Nitrogen, or ammonia, then, directly promotes the growth of stalk and leaves, the vegetative part of the plant.

Phosphoric acid especially promotes the growth and development of the seed, and increases the vigor of the reproductive organs of the plant. When plants make a good growth of stalk and leaf, but produce light and chaffy grain or set few fruits, a lack of phosphoric acid is indicated.

Potash is needed in the formation of starch or cellulose by the plant, and hence plants made up largely of starch cells, like the potato, the turnip and the cabbage, need large quantities of potash. Potash also assists in the formation of the seed, plays an important part in the development of the lint in cotton, adds strength to the straw in grain crops, and color and quality to fruits.

FOUR FACTS TO REMEMBER.

Thus, while each of these elements has a certain part to play in the building up of the plant structure, it is essential that all of them be available in sufficient quantities, since one can not take the place of another and all are necessary for the plant's perfect development.

The reader will remember, however, that the plants cannot use any of the food that is in the soil for them, unless it is dissolved in the soil water so that it can be absorbed by the minute root-hairs which are the feeders of the plant. He will remember, too, that many soils do not hold enough moisture because of their lack of humus — "humus," meaning, as it is used here, decaying vegetable matter. Its effects upon crop growth and the need of most soils for it, will be treated more fully in succeeding chapters. Such soils dry out quickly and the plant food they contain is, to a large degree, useless simply because the crops are not able to take it up. On such soils the addition of humus may help the crops more than the application of plant food. Most Southern soils are deficient in humus, and this is why humus-supplying fertilizers — stable and green manures — produce effects entirely out of proportion to the amount of plant food they contain, as compared with commercial fertilizers which contain very little or no humus.

To recapitulate, then: (1) Fertilizers are substances containing plant food which is usually in a readily available form, and (2) are, therefore, used to supplement the plant food that is already in the soil. (3) Since a liberal supply of soil moisture is necessary to enable the plants to utilize the food in the soil, and since a soil deficient in humus, as most Southern soils are, is almost sure to be subject to extremes of drouth and wetness.

WHAT FERTILIZERS ARE AND WHY USED. 13

the addition of humus to most soils is as important as the addition of plant food; and (4) this is why stable and green manures are worth more — considering the amount of plant food they contain — than commercial fertilizers.

CHAPTER IL WHAT COMMERCIAL FERTILIZERS ARE.

AS HAS been explained, commercial fertilizers are used solely for the plant foods — nitrogen, phosphoric acid and potash — they contain, and have not the effect on the physical standard of the soil which is such a marked characteristic of stable and green manures. Some commercial fertilizers, it is true, contain lime which is often of value in correcting acidity and improving soil texture; but this lime is seldom taken into consideration in estimating the value of these fertilizers, and in this chapter will be left out of consideration.

Commercial fertilizers, as we buy them, are usually mixtures of two or more ingredients, each of which may contain one or more elements of plant food. For example, an "8 — 4" fertilizer — one containing 8 per cent of available phosphoric acid and 4 per cent of potash — is usually made up of acid phosphate and kainit, with sand or loam as a "filler." The common "8 — 2 — 2" fertilizer is likely to be made up of acid phosphate, kainit and cottonseed meal; and so on.

The various materials which go into the make-up of commercial fertilizers may, therefore, be divided into three classes according to whether they supply nitrogen, phosphoric acid or potash. Some of them, it is true, furnish two or even all three of these elements, in which case the percentage of each must be considered.

WHAT COMMERCIAL FERTILIZERS ARE. 15

SOURCES OF PLANT FOOD.

The most common fertilizing materials which supply nitrogen may be divided into two classes, organic and inorganic — those derived from animal or vegetable life, and those that are minerals. In the first class come cottonseed meal, tankage, dried blood, fish scrap, Peruvian guano, etc. In the second class are nitrate of soda, sulphate of ammonia, and two or three other substances seldom used in the South.

There is much difference in the various forms of the nitrogen in these different substances, in the amount of it that can be used at once, the time of its becoming available, etc.; but these points will be treated more in detail in the next chapter.

Phosphoric acid is derived chiefly from acid phosphate and basic slag. The various bone products are gradually being used less and less, and a pound of available phosphoric acid in them usually costs more than in acid phosphate. There is also some phosphoric acid in such organic fertilizers as cottonseed meal, Peruvian guano and fish scrap.

Potash is derived chiefly from the various forms of potash salts taken from the German potash mines — kainit, muriate, sulphate, sylvinit, "manure salts," etc. Of course, some potash is found in practically all fertilizers of vegetable origin, — cottonseed meal, for example, containing about li per cent. Ashes and tobacco refuse are also potash-supplying materials. A special chapter will be devoted to the consideration of potash and the various forms in which it may be obtained.

HOW FERTILIZERS ARE MADE UP.

These, then, are things to be remembered about commercial fertilizers: They are valuable solely as sources of the different plant foods, and their value depends upon the amounts of these foods they contain and their availability for the use of plants; they may be made up of a great many different materials, some of which contain one, some two, and some all three of the plant foods we buy; we may buy one element or one ingredient at a time — nitrate of soda, for example, which supplies only nitrogen; acid phosphate, which supplies only phosphoric acid, or cottonseed meal, which supplies some of each of the three elements, — or we may buy them in a mixture, as is generally done; the standard "brands" of fertilizers usually .sold consist of two or more ingredients mixed together, generally with a valueless "filler" of some sort to bring their value down to the low prices which most people seem willing to pay.

WHAT TO CONSIDER IN BUYING FERTILIZERS.

From these facts it is easy to deduce others: In buying a fertilizer the first thing to consider is the amounts of each of the plant foods it contains and their value; the next thing is the need of the crop, on the special soil where it is to be grown, for these foods. A pound of potash, for example, costs now about 6 cents, on the average; a pound of phosphoric acid, about 51 cents, and a pound of nitrogen, about 2 cents. A farmer can easily ascertain from these figures which of two fertilizers is the cheaper source of any of these plant foods.

WHAT COMMERCIAL FERTILIZERS ARE. 17

Again, some crops need much larger quantities of certain elements than do others. An amount of nitrogen that would give an excess for an oat crop might be insufficient for a corn crop on the same land.

Soils also differ widely in their demands for the various elements. The sandy slopes of the Atlantic Coast need large amounts of potash, while on the black lands of the Mississippi Valley it almost never gives profitable returns.

It thus becomes evident that the farmer must know what each plant food does for his crop, the commercial value of each food, the amounts of each that his fertilizers contain, and something of the demands of his crop and his soil for these foods, before he can buy or use fertilizers intelligently and to the greatest profit.

Chapter III. What Nitrogen Does And Where We Get It

WHILE NITROGEN is found in various forms or combinations in the different fertilizers, there is only one form in which it can be used as food by plants — the form which the chemists call nitrate. The nitrogen in ammonaic compounds must be> changed, by the action of bacteria, to this nitrate form before it can be used; while that in organic matter — green crops, cottonseed meal, or stable manure — must first be changed to ammonia by one class of bacteria, and then to nitrates by another class.

This explains why the nitrogen in nitrate of soda is so much more quickly used by plants than that in cottonseed meal or in a turned-down green crop. In the first case it is ready to be dissolved by the soil moisture and at once taken up by the root-hairs to feed the plant; in the other it must be acted upon by two sets of bacteria which do this work of making the nitrogen compounds available for use — "ammonifying" and "nitrifying" bacteria they are called. These bacteria work best in a loose soil, where there is a good supply of moisture, considerable warmth and plenty of air. Tillage greatly aids their work, while an excess of water in the soil will almost entirely stop it. In a very wet season crops may turn yellow and cease to grov/ simply because the soil bacteria can not perform their work and no nitrogen is made available as plant food.

WHAT NITROGEN DOES AND WHERE WE GET IT. 19

AVAILABLE AND UNAVAILABLE NITROGEN.

From this it will be seen that the different nitrogenous fertilizers — those supplying nitrogen — are adapted to special purposes. Nitrate of soda is the most readily available of those commonly used, and should be applied, as a rule, to growing crops where it can be used before it is leached out of the soil by rains. In many cases where it is applied even at planting time, large percentages are lost before the crops can use it. The nitrogen in sulphate of ammonia is not quite so readily available as that in nitrate of soda, but is ready for use sooner than that in fish scrap or tankage or cottonseed meal or stable manure. Peruvian guano is a splendid source of nitrogen for most crops because there may be found in it various forms of nitrogen, some readily available and others which will only gradually become so.

These facts must all be taken into consideration in buying fertilizers for any crop. If the fertilizer is to be applied before the crop is planted, the nitrogen may be supplied by cottonseed meal or stable manure; if at planting time, the ideal would probably be to have some ready for use at once, some that would be so in a little while and some, again, that would only become available as the growth of stalk and leaf neared completion. For example, in using a fertilizer for fall-sown wheat or oats, the nitrogen might largely be supplied by the roots and stubble of a leguminous crop; but there would also be needed a little of some quicker-acting form to supply the needs of the crop during the winter and early spring when nitrification — that is, the changing of the insoluble nitrogen to the available nitrate form — takes place very slowly. If the crop in the spring is yellow and scrubby, a top dressing of nitrate of soda will be the best thing to start it off to immediate growth. The same fertilizer would be the best for rapid-growing garden or truck crops; while for corn, with its heavy root growth and the rapid nitrification that takes place during the summer, stable manure or a turned-down green crop is probably best of all.

AMOUNTS OF NITROGEN IN VARIOUS FERTILIZERS.

As sources of nitrogen, then, nitrate of soda is the most readily available, the most easily lost from the soil, and the best for short-lived, quick-growing crops; sulphate of ammonia is a little less readily available; while vegetable and animal fertilizers furnish nitrogen in the best form for crops whose growth is comparatively slow and whose needs are best met by a supply which gradually becomes available.

The percentages of nitrogen contained in the most commonly used fertilizers are as follows: Dried blood, high grade, 13 to 14 per cent; low grade, 6 to 12 per cent; fish scrap, 7 to 8 per cent; tankage, 4 to 10 per cent; cottonseed meal, 6.2 to 6.8 per cent; sulphate of ammonia, 2 per cent; nitrate of soda, 15.5 per cent. There is a wide variability in the composition of all organic fertilizers and they should always be bought by analysis — that is, the price should be determined by the amounts of plant food they actually contain.

JWHAT NITROGEN DOES AND WHERE WE GET IT. 21

Right here it may be well to say that ''ammonia" is a nitrogen compound, of which 82.35 per cent is nitrogen. That is, the percentage of ammonia in a fertilizer may be reduced to its equivalent in nitrogen by multiplying by .823 5. Three per cent ammonia means 2.47 per cent of nitrogen. Similarly, to reduce nitrogen to terms of ammonia, it should be divided by .823 5. For example, a fertilizer containing 3.5 per cent nitrogen contains 3.5 -^. 8235, or 4.22 per cent of ammonia.

HOW NITROGEN SHOULD BE OBTAINED.

The buying of nitrogen in commercial fertilizers for most farm crops is not a practice to be recommended, since it is the most expensive and the most easily lost plant food, and since, by the growing of leguminous crops, unlimited quantities may be obtained from the air. For truck and garden crops, on the other hand, the readily available forms in commercial fertilizers should be used in addition to the organic forms.

It has been estimated that a crop of cowpeas making two tons of hay to the acre will have gathered from the atmosphere 130 pounds of nitrogen, worth $26.00 to the soil, and other leguminous crops may do as well. It is easy to see that it is much better to get nitrogen in this way than by buying it at 2 cents a pound, especially as the legume practically always has a feeding value great enough to make its growing profitable without takingthis addition of nitrogen to the soil into consideration.

All crops that make a large or rapid growth of leaves and stalks need liberal supplies of nitrogen, and where the growth of these is insufficient its need is clearly indicated. An excess of nitrogen, however, will produce too great growth of stalk and leaf at the expense of the fruiting qualities of the plant — for example, potatoes "running to tops," or cotton "going to weed."

Chapter IV. About Phosphoric Acid

&rw-«HE SPECIAL purposes served by phosphoric acid in I the building up of the plant structure have already been mentioned — increased fruitfulness and added weight of grain or seed together with earlier maturity.

The absolute necessity of an abundant supply of this element to promote these processes, and the comparatively small amount that is available in the ordinary soil, have combined to make it the leading ingredient of most commercial fertilizers. Perhaps the fact that it is, pound for pound, the cheapest of the three elements usually bought, also helps to account for this; but there is, in most cases, a sound reason for the comparatively large percentage of phosphoric acid in the ordinary commercial fertilizer.

Many people remembering the large quantities of this element applied to many Southern soils year after year, and considering also that very little indeed is lost from the soil by leaching, conclude that it is a wrong policy to continue to buy phosphoric acid, since, as they reason, most soils should be well supplied with it already.

THE LARGE SUPPLIES OF PLANT FOOD IN THE SOIL.

They forget that even on the most heavily fertilized soils all that has been applied would amount to an almost inconceivably small percentage, that most soils contain proportionately much less of this than of the other elements, and that when it is applied to the soil it may "revert" back to an insoluble form and be unavailable for the use of plants. The top six inches of soil on an acre of ordinary land may contain from 1% to 1% tons of phosphoric acid — as much as would be applied in 156 tons of acid phosphate, or enough to produce good ordinary crops for more than 500 years. The trouble is simply that a very small part of it is in such form that it can be made use of by the crops. What is applied in fertilizers is supposed to be in such form that it can be used at once, and is applied for this reason,

"AVAILABLE" AND "UNAVAILABLE" PHOSPHORIC ACID,

Phosphoric acid, then, is found in two forms: Available, or soluble, — when it can be used by the plants; and insoluble, or unavailable, — when it can not be used.

It must be remembered, however, that all "available" phosphoric acid is not equally available. Some of the various forms which the chemists group under this term are much more readily taken up by the plant than are others; while all of them are likely to undergo changes in the soil — to make other chemical combinations — and thus to pass from a soluble state to one partially or wholly unavailable. On the other hand, tillage, plant growth and bacterial action are all the time changing the insoluble forms of all the plant foods into available forms. This explains why a soil may contain large stores of plant food and at the same time make very small crops, and also why no soil can be entirely exhausted of plant food and made utterly unproductive.

ABOUT PHOSPHORIC ACID. 25

THE PRINCIPAL PHOSPHATIC FERTILIZERS.

The principal commercial sources of phosphoric acid are raw phosphate rock, acid phosphate, bone meal and basic slag.

Bones contain in their raw state from 18 to 2 5 per cent of phosphoric acid, which becomes very slowly available. Steamed bone, from which the fat and tissues have been largely removed, contains 22 to 2 8 per cent in a more readily available form; while bone dissolved with sulphuric acid contains from 15 to 17 per cent, which is practically all available. Bone meal is usually the steamed bone ground, and its immediate availability depends largely on the fineness to which it is ground. In addition to the phosphoric acid, raw bone contains from 2 to 4 per cent of nitrogen; steamed bone, l^^ to 2 l^ per cent, and dissolved bone, from 2 to 3 per cent. All the bone fertilizers are what are called "durable" fertilizers, — that is, they become available a little at a time for many years. For this reason they are especially adapted for use on permanent grass fields and for orchard trees.

Basic slag, or Thomas phosphate, is a by-product from the refining of iron ore for steel making. It contains 18 to 2 4 per cent of phosphoric acid and about 30 per cent of lime. The phosphoric acid is less available th^n that in acid phosphate.

Phosphate rock, containing from 2 4 to 3 2 per cent of phosphoric acid, is mined in South Carolina, Florida, and 3

Tennessee, and has lately been found in several Western States. When ground in its natural state it is known as raw rock, or "floats," and all the phosphoric acid in it is regarded as unavailable. When mixed with stable manure or with any considerable quantity of decaying vegetable matter, it will, however, gradually be changed into forms that the plants can use.

Ordinarily this raw rock is treated with about its own weight of sulphuric acid, thus forming acid phosphate, the most common source of phoshoric acid. From 14 to 16 per cent of available phosphoric acid is usually found in acid phosphate and in no other fertilizer, perhaps, is the phosphoric acid so readily soluble in the soil water and thus so quickly used by the plants.

Cottonseed meal contains about 2 V2 per cent of phosphoric acid; fish scrap, 3 to 4 per cent; Peruvian guano, 10 to 15 per cent, and tankage, 1 to 2 per cent.

For most crops acid phosphate is probably the cheapest and most effective source of available acid phosphate. On acid soils basic slag, although a little less readily available, may on account of the lime it contains give better results; while on soils very full of vegetable matter, floats may often be used ^o advantage.

Most Southern soils are deficient in phosphoric acid, and its application in some form is a necessity if these soils are to be improved. Most lands, however, if given better tillage, well drained, and well supplied with humus, would beyond all question, make much better use of what was applied and give far greater returns from equal quantities than at present.

Chapter V. Potash In Commercial Fertilizers

OST READY-mixed fertilizers contain potash In quantities varying from 1 per cent to 5 per cent, and there could probably be no better evidence than this offered as to the inadvisability of buying fertilizers just because they are called "corn" or "cotton" or "tobacco" fertilizers. For some crops on most soils, and for practically all crops on some soils, the percentages of potash in most ready-mixed fertilizers are entirely too small, while there are other soils on which it seems to be an absolute waste to supply potash at all. The sandy soils of the Atlantic Coast need liberal supplies for the general crops, corn, cotton, and small grains. On the red clay soils of the Piedmont and mountain sections of the South, potash is needed for special crops — fruit and truck, potatoes, etc.; while on the soils of the Gulf States, even on the sands ot southern Mississippi and Alabama, potash does not seem to be needed even for. these crops. In other words, the cotton farmer on the coastal plains of North and South Carolina v^^ho buys a "2 — 8 — 2" fertilizer does not get nearly so much potash as his crops demand, while the cotton farmer in southern Missississippi who buys the "2 — 8 — 2" fertilizer wastes practically $2.40 for every ton of such fertilizer he buys, since experiments have shown that on his soil the addition of potash produces no noticeable effect.