Crops and Methods for Soil Improvement Part 9

The peculiar situation respecting animal bone has come about through a form of deceit. The demand for bone existed, and there was no legal restraint in the matter of branding phosphatic rock as "bone,"

"bone-phosphate," etc. In the past, nearly all forms of rock-phosphates have carried the word "bone" on the bag to quiet the apprehension of those who entertained a prejudice against anything other than animal bone. Nearly all the phosphoric acid has come from rock, and its use has been necessary and profitable, but the misrepresentation fostered the old-time prejudice. Within recent years some manufacturers have tired of the seeming deceit that served no purpose with many customers, and have placed acid phosphate and mixed goods upon the market without the intimation that the phosphoric acid was derived from animal bone.

The demand for bone makes prices high for the very limited amount upon the market, when availability is taken into account, and the advice that such goods be used would be valueless if it had any general acceptance. Prices would go higher, and the amount in the world would remain wholly inadequate.

Raw Bone.--Stable manure lasts several years in the soil because decay is slow. Raw bone has appealed to many because its action is likewise necessarily slow. The fat in it prevents fine grinding and protects the coa.r.s.e particles from decay. It is known as bone-meal or coa.r.s.e ground-bone. A good quality of raw bone may contain 4 per cent of nitrogen, while the phosphoric-acid content is 20 to 25 per cent. The bones of old animals is less rich in nitrogen. The age of the animals, and the sorting for manufactures of various kinds, cause variation in quality, and the purchase of raw bone should be made on guaranteed a.n.a.lysis just as surely as the purchase of bone that has been treated in any way for removal of various substances in it.

Steamed Bone.--When animal bone is boiled or steamed under pressure for removal of the fat and the cartilage, the content of nitrogen is reduced, and the percentage of phosphoric acid is increased by this removal of fat and nitrogenous substance. The nitrogen in steamed bone may run as low as 1 per cent, and the phosphoric acid may go up to 30 per cent. The composition of steamed bone is so widely variable that the name means little, and purchase should be made only on guaranteed a.n.a.lysis. Some grades run very low both in nitrogen and phosphoric acid, due probably to adulteration.

The boiling or steaming of bone makes fine grinding possible, and the fineness and absence of fat permit quick decay in the soil. Steamed bone is an excellent source of phosphoric acid. The availability is less immediate than that of acid phosphate, but much greater than that of raw bone.

Rock-phosphate.--While the greater part of our soils contain relatively scant stores of phosphoric acid, the deposits of this plant const.i.tuent in combination with lime are immense. The rock now chiefly used in this country is found in South Carolina, Tennessee, and Florida. It varies greatly in content of phosphoric acid. When pulverized for direct use on land, without treatment with sulphuric acid to make the plant-food available, a grade running 28 per cent phosphoric acid, or less, usually is selected, the higher grades being reserved for treatment with acid or for export. This untreated rock, pulverized exceedingly fine, often is known as floats.

The value of a pound of phosphoric acid in floats, as compared with that of a pound in the treated rock, known as acid phosphate, is a matter upon which scientists differ widely. Only a small percentage of the plant-food is immediately available, and the question of wise use hinges upon the degree of availability gained later, and the time required. The large amount of experimental work that has been done affords data that causes the following opinion to be stated here: Rock-phosphate, known as floats, is not a profitable source of plant-food for soils deficient in organic matter, when compared with acid phosphate. It is more nearly profitable in an acid soil than in one that has no lime deficiency. It gives more satisfactory results when mixed intimately with stable manure than when used upon land that remains deficient in organic matter. Applications should be in large amount per acre--500 to 1000 pounds--in order that the amount of readily available phosphoric acid may meet the immediate need of plants. Dependence should be placed upon the readily available acid phosphate in all instances until experiment on the farm shows that the rock-phosphate is a cheaper source of plant-food than the acid phosphate.

Acid Phosphate.--When animal bone is treated with sulphuric acid, the result is an acid phosphate, but treated animal bone is so rare on the market that it may be ignored. The acid phosphate on the market is rock-phosphate treated with sulphuric acid to render its plant-food available. The content of phosphoric acid varies because the original rock-phosphate varies, but the most common grade on the market is guaranteed to contain 14 per cent available phosphoric acid, and 1 to 2 per cent insoluble. Some acid phosphate is guaranteed to contain 16 per cent available phosphoric acid, and some runs down to 10 per cent available.

An acid phosphate contains quickly available plant-food. A prejudice exists against it on account of its source, and it has been a common practice to label the bags "bone-phosphate," or "dissolved bone," or such other designation as would imply an organic source, but the acid phosphate is made out of rock-phosphate, regardless of the name given.

The prejudice against the rock as a source of plant-food is giving way.

It is our chief and cheapest source of supply. The combination of sulphuric acid with rock-phosphate in the production of acid phosphate produces sulphate of lime, known as gypsum or land-plaster. The amount of gypsum in a ton of acid phosphate varies, but may be roughly estimated by the buyer as two thirds of the total weight of the acid phosphate.

The tendency of gypsum is, in the long run, to make a soil acid, and its use necessarily hastens rather than r.e.t.a.r.ds the day when a lime deficiency will occur. The influence in this direction is not great enough to be a very material factor in deciding upon a carrier of phosphoric acid. If a soil has little lime in it, a state of acidity soon will come anyway, and the increase in amount of required lime will be small. The cheapness of acid phosphate, as compared with animal bone, is the decisive factor.

The ill-effects usually attributed to acid phosphate are not due in any great degree directly to the sulphuric acid used in its making, but to the bad farming methods that so often attend its use. When the need of commercial fertilizers is first recognized, acid phosphate seems to meet the need. The soil's store of available phosphoric acid gives out first, and this fertilizer brings a new supply. If the available potash is in scant amount, the acid phosphate helps in this direction by freeing some potash. The phosphoric acid has peculiar ability in giving impetus to the growth of a young plant, and that enables it to send its roots out and obtain more nitrogen than it otherwise would do. The farmer thus may come to regard it as a means of securing a crop, and there is neglect of manure and clover. If a field is thin and fails to make a sod, there is no immediate compulsion to use manure or to grow a catch crop to get organic matter, but the field is cropped again with grain. Soon the supply of humus is exhausted, the soil lies lifeless, and the stores of available nitrogen and potash are in a worse depleted state than formerly.

The fault lies with the method. The phosphoric acid in the acid phosphate was needed. Profit from its use was legitimate, but the necessity of supplying organic matter became even greater than it would have been otherwise. Tens of thousands of our most successful farmers use heavy applications of acid phosphate, but they keep their soils in good physical condition by the use of manure or clover, and they apply potash and nitrogen when needed. The clover is a.s.sured by using lime wherever it is in too limited supply, and that is the case in most instances, regardless of the use of any kind of commercial fertilizer.

Basic Slag.--When iron ores contain much phosphorus, its extraction by use of lime gives a by-product in the making of steel that has agricultural value. The ores of the United States usually do not give a slag sufficiently rich in phosphorus to be valuable. Nearly all the basic slag used as a fertilizer is imported from Germany, and usually contains 17 to 18 per cent of phosphoric acid. The availability of the plant-food in this fertilizer has been the subject of much discussion.

The chemist's test which is fair for acid phosphate is admittedly not fair when used for basic slag. Field tests, at experiment stations and on farms, are our best sources of knowledge. When the soil is slightly acid, each 1 per cent of phosphoric acid in the slag appears to be about as valuable as each 1 per cent of the available phosphoric acid in an acid phosphate. Some of the effectiveness may be due to the lime, although very little of it is in forms regarded as valuable for the correction of soil acidity. There is evidence that basic slag favors clover. It has not been found feasible to ship this material many hundreds of miles inland from the seaboard to compete with acid phosphate, but it is an excellent source of phosphoric acid for soils that are not rich in lime.

Muriate of Potash.--The mines of Sta.s.sfurt, Germany, contain an inexhaustible supply of potash in various compounds. Muriate of potash is prepared from the crude salts, and the commercial product on our markets has the appearance of a coa.r.s.e and discolored salt. It is handled in large bags, and inclines to become moist by absorption of water from the air. It contains some common salt. The content of actual potash is about 50 per cent. The potash is readily available, but the loss from leaching out of the soil is very small. Muriate of potash is our cheapest source of potash, and should be used for all staple crops except tobacco, sugar beets, and, possibly, the potato. Tests even on heavy soils fail to show any injury to the quality of the potato, and on light soil the muriate may always be used.

Sulphate of Potash.--Some sulphate of potash is imported into this country. Its content of potash may vary 1 or 2 per cent below or above 50. Its physical condition favors mixing more than does the muriate. It usually costs several dollars a ton more than the muriate, and the fact that it is known to favor quality in tobacco, and is popularly supposed to do so in the potato, creates demand at the higher price. It is soluble in water, and quickly available. As a rule, it has no higher agricultural value than the muriate.

Kainit.--Unlike muriate and sulphate of potash, kainit is a crude product of the German mines, having received no treatment to remove impurities. It contains 12 to 13 per cent of potash, and is rated as a sulphate, but one third of it is common salt, and in effect upon quality it should be cla.s.sed with muriate and not sulphate. Its low content of plant-food should confine its use to regions relatively near the seaboard. When shipped far inland, the price becomes too high to give a reasonably cheap pound of potash.

Wood-ashes.--Wood-ashes contain lime and potash, with a small percentage of phosphoric acid. The market price is above agricultural value, and any needed potash should be obtained from the German potash salts.

Other Fertilizers.--Manufacturers of commercial fertilizer make use of other materials, some of which, like manufactured nitrogen, are excellent, and others are low in quality and slow in action. The sources of plant-food that have been described form the great bulk of all fertilizers on the market, and from them may be selected all the materials a farmer needs to use on his land, either singly or home-mixed. In most instances the selection will embrace only four or five of these fertilizing materials.

Salt.--Salt is not a direct fertilizer, and its use is not to be advised unless it can be secured at a very low price per ton. Some soils have been made more productive by the application of 200 to 300 pounds per acre, and chiefly in case the salt was mixed well with the soil when the seed-bed was made. The practice of using salt as a top-dressing on wheat in the spring gives less effectiveness it is believed. Salt frees potash in the soil, and may have some practical effect upon soil moisture. As a soil amendment, salt has had more reputation than its performance justifies. If land is infertile, it is better, as a rule, to apply actual plant-food.

Coal-ashes.--There is no plant-food of value in coal-ashes. The physical condition of heavy soils is improved by an application, and their use may be quite profitable in this way if cost of application is small. When used as a mulch, ashes conserve moisture.

Muck.--The use of muck pays in stables, as it is a good absorbent and contains some nitrogen which gains in availability by mixture with manure. Its direct application to land as a fertilizer does not pay the labor bill under ordinary circ.u.mstances.

Sawdust.--As a fertilizer, sawdust does not have much value, but serves as an excellent absorbent in stables. Its presence in manure need not cause fear of injury to the soil. When fresh sawdust is applied in large quant.i.ty to a sandy soil, the effect upon physical condition is bad, increasing drouthiness.

CHAPTER XVIII

PURCHASING PLANT-FOOD

Necessity of Purchase.--The necessity of buying plant-food in the form of commercial fertilizers is a mooted question in any naturally fertile agricultural region just so long as crop yields do not drop to a serious extent. The natural strength of the land and the skill that enters into the farming are important factors in determining the profitableness of recourse to purchased plant-food. The free use of organic matter to maintain the supply of humus defers the time when commercial fertilizers should be used. Good tillage frees the potential plant-food of the soil, and delays the day of necessary purchase. The farm so situated that it can have all its products fed upon it is longer independent of outside help. The profitable use of feeding-stuffs from other farms is a safe way of escaping the direct purchase of fertilizers, although it is a transfer of fertility to the farm as surely as the employment of fertilizers, and is not a method that may have general adoption.

[Ill.u.s.tration: In the Lebanon Valley, Pennsylvania.]

The organic sources of fertility, such as slaughter-house refuse, are containers of plant-food as surely as is stable manure. The inorganic sources, such as acid phosphate and muriate of potash, are containers of plant-food as surely as is animal bone or blood. There is no line that may be drawn to debar any substance that supplies plant-food profitably and contains no compound harmful to the soil.

The purchase of plant-food should begin whenever profit is offered by it, and in connection with its use there should be good tillage, organic matter, and healthful plant conditions in every respect. The use of a fertilizer pays best when the conditions are such that the plants can avail themselves of it in the fullest degree. Good farming and the heavy use of commercial fertilizers go consistently hand-in-hand.

Fertilizer Control.--The dreams of the patent-medicine vender never pictured more favoring conditions for his activity than were found by fertilizer manufacturers and agents before state laws provided for inspection and control. Men who wanted to do a legitimate business welcomed protection from the unscrupulous compet.i.tion that dishonest men employed. The memory of some of the frauds perpetrated lingers, and causes a questioning to-day that is unnecessary. All fertilizer-control laws afford a good degree of legal protection to the buyer, although in most states they do not demand a clearness and fullness in statements of a.n.a.lyses that would be helpful to many, and they fail to require that sources of plant-food be given. Some fertilizers are sold for more than they are worth, and some are bought for soils and crops that need other kinds of plant-food, but this is due to lack of knowledge on the part of the buyer that he can acquire. The law does its part in the work of protection better than many buyers do their part. It has driven fraudulent brands off the market, compelled carefulness in factory-mixing, and given to the intelligent buyer a knowledge of the kinds and amounts of plant-food in the bag or ton. The sampling is done by disinterested men, and the a.n.a.lyses are made by competent chemists.

There need be little distrust of the a.n.a.lysis as printed on the bag, unless a failure of the manufacturer to keep his goods up to the standard has been made public in the state's fertilizer bulletin.

Brand Names.--Notwithstanding all that has been done by the state to acquaint the buying public with the composition of fertilizers, many purchasers are guided in selection by the brand name, and that usually is fanciful in character, no matter whether it be "Farmers' Friend" or "Jones' Potato Fertilizer." In either case it may be far from friendly to soil or pocket-book, and widely at variance with the needs of the soil for which it is purchased. The pretense of making a fertilizer peculiarly adapted to the potato, or to wheat, or to corn would not attract a single buyer if the public would compare the a.n.a.lyses of these special crop fertilizers offered by manufacturers and note their dissimilarity of composition. Any kind of a mixture may be given any kind of a name. It is the composition that counts. The farmer is in the market for nitrogen and phosphoric acid and potash, singly or combined, for a certain soil, and all he wants is to know the number of pounds he is getting, its availability, and its price per pound. Any added detail not required by law is an impertinence.

Statement of a.n.a.lysis.--It would be well if the law refused to the manufacturer the privilege of printing unnecessary detail in the statement of a.n.a.lysis that must be placed upon the fertilizer bag. It is added to confuse the buyer and mislead him regarding actual value.

The following statement is an example of this practice:

a.n.a.lYSIS

Per Cent Nitrogen 0.82 to 1.00 Equal to ammonia 1.00 to 2.00 Soluble phosphoric acid 6.00 to 7.00 Reverted 2.00 to 3.00 Available 8.00 to 10.00 Insoluble 1.00 to 2.00 Total 9.00 to 12.00 Potash (actual) 1.00 to 2.00 Equal to sulphate of potash 2.00 to 3.00

As the row of larger figures is not guaranteed percentages, it has no value.

The buyer is not concerned regarding the amount of ammonia to which the nitrogen is equal, and so the second line is a needless repet.i.tion.

The fifth line gives the sum of the third and fourth, the available being the total of the soluble and reverted. Therefore the third and fourth lines may be ignored.

The sixth line gives the percentage of unavailable phosphoric acid in the rock, and should be ignored by the purchaser who wants available plant-food.

The seventh gives the sum of the available and insoluble, and should be ignored.

The ninth is a restatement of the eighth line.

There then remains the following guaranty:

Per Cent Nitrogen 0.82 Available phosphoric acid 8.00 Potash 1.00

This is a low-grade fertilizer whose cheap character becomes apparent when the unnecessary statements and restatements are erased. A ton of it contains only 16 pounds of nitrogen, 160 pounds of phosphoric acid, and 20 pounds of potash.

Valuation of Fertilizers.--The manufacturer of a mixed fertilizer must make use of the unmixed materials he finds upon the market. The prices of the various plant const.i.tuents in the different unmixed materials can be determined by averaging quotations in leading markets for a given length of time. The fair retail price is obtained by adding about 20 per cent to the wholesale cash price. The retail cash price per pound of the plant const.i.tuents in leading markets is thus determined for their various forms and carriers. A pound of nitrogen in dried blood may have its valuation fixed at a figure 50 per cent higher than that of a pound of nitrogen in nitrate of soda simply because the dried blood sells at a price per ton that makes that difference. It is true commercial value that is sought, and that may be very different from agricultural value.

The mixed fertilizer of the manufacturer has its content of plant-food known by a.n.a.lysis. Its number of pounds of the various const.i.tuents in a ton is known, and the retail price per pound of these substances has been fixed. The commercial value per ton can then be determined, provided proper allowance is made for cost of mixing and bagging. The individual must pay in addition the freight, and usually a considerable sum for unnecessarily costly methods of distribution and collection.

A Bit of Arithmetic.--This paragraph is intended to serve the man who is willing to be reasonably near right if he cannot be wholly so: A ton is 2000 pounds, and one per cent is 20 pounds. In dealing with fertilizers it is the practice to call 20 pounds, or one per cent of a ton, a unit, and to base the price of the nitrogen, and phosphoric acid, and potash, on the unit. This is done for convenience. If five cents is a fair price for a pound of available phosphoric acid in one's locality, as it would be if a ton of 14 per cent acid phosphate cost $14, a unit of 20 pounds is worth $1. Each one per cent guaranteed is thus worth a dollar, and the phosphoric acid in the fertilizer is easily valued. If a pound of potash in a ton of muriate is worth five cents in one's locality, as it would be if a ton of muriate cost $50, the muriate being one half actual potash, a unit of 20 pounds of potash is worth $1. Each one per cent of guaranteed potash is thus worth one dollar, and the entire content of potash is easily valued. If a pound of nitrogen in nitrate of soda is worth seventeen and one half cents a pound in one's locality, as it would be if a ton of nitrate of soda cost $54, a unit, or one per cent, is worth $3.50, and the content of nitrogen is easily valued.