Fertilizer

in agriculture, any substance added to the soil to stimulate plant growth. Plants need certain elements for growth. Any substance that furnishes one or more of these elements, or that makes available an element already in the soil, may be regarded as a fertilizer. In a broad sense water is a fertilizer. Water is needed for plant growth, and water acts on soil to free elements needed by vegetation; but the term fertilizer is held usually to include only barnyard manures, green manures, and commercial fertilizers.

BARNYARD MANURES are the best for general purposes. A ton of barnyard manure may not contain more than thirty or forty pounds of the food required by plants; but, in rotting in the ground, the coarse stuff may act on the particles of soil and set several hundred pounds of plant food free, and not only that, the rough part of the manure aids the soil in holding moisture. The principal elements of plant food contained in barnyard manure are nitrogen, phosphoric acid, and potash. One ton of average stable manure contains about 10 pounds of nitrogen, 10 pounds of potash, and 5 pounds of phosphoric acid.

Animals fed on nitrogenous foods, as clover, alfalfa, bran, oilmeal, oats, and cottonseed meal, supply manure rich in nitrogen. Animals fed chiefly on wild hay, straw, corn fodder, and timothy do not yield manure of as valuable a quality. Young growing animals, as colts and calves, and lean animals,--animals needing the nutritious elements of food for their own growth,--do not supply as valuable barnyard manure as older animals and fat animals. Manure from fattening steers and fat hogs is particularly rich in plant food. Building up bone and meat requires the elements that otherwise go to make rich manure. Putting on more fat requires the elements that plants derive from the air, and leaves for the manure pile the elements that the plants derive from the soil,--nitrogen, phosphoric acid, and potash, which, if returned to the soil, restore its fertility. The guano from the poultry yard is a highly concentrated fertilizer.

THE CARE OF MANURE is of first importance. Dry manures, such as are obtained from horses, sheep, and poultry, are likely to heat,--a process that liberates nitrogen, one of the very elements most desired for the field. A "smoking" manure pile loses strength rapidly, and becomes about as valuable as so much straw. Dry manure may be prevented from "burning" by keeping the pile moderately wet or by mixing it with the cold and wet manure from the cow barn and pig pen. A manure pile should on no account be allowed to leach. The colored liquid that runs away from the pile during a rain is precisely what the soil requires. Its escape is quite as wasteful as rat holes in a granary. If a pile is to be formed, it should be made in a hollow spot. A concreted bottom saves its cost many times over. A broad, flat pile, tramped thoroughly by stock, saves the strength of the manure best. Droppings around the yard should be thrown into the pile, winter and summer. Stable liquids are exceedingly valuable; they should be absorbed by bedding and be added to the pile. Straw bedding is best for the land. Sawdust is most desirable in the stable, but it decays so slowly that it is a detriment to the field.

THE USE OF MANURE. Good farmers declare that manure should be scattered on the land fresh. Piles of manure dumped in the field leach badly. The immediate spot receives more plant food than it can utilize and the coarse litter spread by a fork later has lost much of its strength. In case of sheep pens, calf pens, and small feeding pens generally, excellent results are obtained by allowing the manure to remain under foot till spring. The droppings, bedding, and liquids are saved perfectly and are tramped into a compact bed of valuable fertilizing material. For manure that must be removed daily, as is decidedly the case in dairy barns and horse stables, it is considered advisable to send to the field as often as a load accumulates. A basket manure carrier running on a wire and dumping into a manure spreader is the modern method of disposing of manure. As often as the spreader is filled, it is driven afield, and the manure is scattered in fine bits. The leaching that follows, always provided the ground be moderately level, enriches the soil uniformly. The latter may be plowed under at convenience. Frequent light dressing gives larger yields than a heavy application of manure at long intervals.

GREEN MANURE. One of the least laborious methods of fertilizing land is that of plowing under green manure, that is to say, turning under a growing crop. Rye, grasses, and particularly clover and other legumes, make the best crops for this purpose. A growth of weeds turned under before the seeds mature is beneficial to the soil. Early plowing of stubble before the undergrowth is taken by frost is an excellent practice. The green growth not only adds fertility to the soil directly, but the acids of decay etch the soil particles and form compounds that feed the next crop. The humus formed by the green manure benefits both clay and sand. Contradictory as the statement may seem, green manure makes clay soil warm and mellow, while it makes sandy soil cooler and more compact.

COMMERCIAL FERTILIZERS may be defined as highly concentrated manufactured plant foods. They differ widely incomposition. If the need of a particular soil be known, a fertilizer may be chosen to supply the element or elements especially needed. The disadvantage of these fertilizers is that they do not supply humus; but there are other advantages. They are free from weed-seeds. They may be applied in small quantities in the hill or row, and they are available immediately for plant growth. Gardeners and others tilling intensively favor these fertilizers, not only for the reasons named, but also because they are not bulky and afford no litter to interfere with tillage.

As stated, the chief elements of fertilizers are three,--nitrogen, phosphoric acid, and potash. The following is a description of the best known fertilizers:

NITROGEN FERTILIZERS.

1. Guano. The droppings of fish-eating sea birds in a rainless climate. Certain islands off the Peruvian coast have for many years furnished guano, but the deposits accumulating for centuries have now been well nigh exhausted. Sometimes the droppings from the poultry yard are called guano.

2. Cotton-seed meal. This is a pomace left after the oil has been pressed out of cottonseed.

3. Dried blood from the slaughtering houses. This is a quick-acting fertilizer and contains about twelve per cent of nitrogen.

4. Refuse or tankage from the slaughtering yards. It consists of all manner of odds and ends--intestines, bones and waste--dried and ground into meal.

5. Dried fish or fish guano, made from a kind of fish called menhaden, bought for the purpose in quantities along the Atlantic coast. It may be recalled in this connection that the Indian taught the Plymouth settler to put a fish in each hill of corn.

6. Chile "saltpeter," a nitrate of soda obtained from the rainless region of Chile. It contains as high as sixteen per cent of nitrogen. Chile shipped 2,000,000 tons in 1908.

7. Chemical nitrogen fertilizers, a convenient term under which to group a variety of fertilizers obtained in the manufactures.

PHOSPHORIC ACID FERTILIZERS.

1. Ground bone or bone meal is rich not only in nitrogen, but it contains as high as twenty-two per cent of phosphoric acid. There are a number of varieties.

2. Rock phosphate, a fossil guano it is thought, found in layers in Tennessee, South Carolina, and Florida. The rock is ground fine and is shipped in shape for application. It is used largely in the Aroostook potato region of Maine. It yields immediate results. The percentage of phosphoric acid runs from twenty-six to forty per cent, the Florida phosphate being richest. In 1907 the United States produced 2,265,000 tons of phosphate rock. In 1908 large tracts of phosphate lands in Utah, Idaho, and Wyoming were withdrawn from public entry.

3. Phosphoric slag, a by-product obtained in the manufacture of steel. It is reduced to a fine powder and contains from fifteen to twenty per cent of phosphoric acid.

4. Chemical phosphates or super-phosphates. A number of these fertilizers are made by treating ground bone and phosphate rock with sulphuric acid. They are used extensively because plants may begin to feed on them without waiting for chemical action in the soil. They produce instant results. A starving plant shows the effect of such a fertilizer almost as quickly as a wilting plant shows the effect of moisture.

POTASH FERTILIZERS.

1. The unleached ashes, especially of hardwoods, supply potash. Beech ashes contain sixteen per cent; elm twenty-four per cent; oak ten per cent. Ashes exposed to rain until the lye has leached away have little value as fertilizers.

2. Tobacco stems. These contain about eight per cent of potash.

3. Chemical potash. Several localities in Germany are noted for commercial potash. Some of these potashes are found in deposits of chemical salts; others are the products of chemical factories. They are used extensively on soils lacking in potash. The German potash trust sells about $24,000,000 worth of potash yearly. About half of it is purchased by the German gardeners.

In addition to the fertilizers named, lime is used widely as a corrective for "sour" soil. It makes clay more mellow. Burnt limestone, ground limestone, gypsum, or land plaster, crushed shells, and marl are applied for the purpose. As stated, commerical fertilizers do not supply humus. The best results are obtained by their use in combination with barnyard manure. They are applied usually by means of drills attached to the machine or implements used in planting seed. The mistake must not be made of supposing for a moment that fertilizers take the place of tilth and moisture.

The following paragraph written by Professor Voorhees gives an excellent idea of the cash value of manure to the farmer:

A farmer should realize that a well fed dairy cow will, on the average, produce 12 3/4 tons of manure per year, and that this product will contain on the average 117 pounds of nitrogen, 77 pounds of phosphoric acid, 89 pounds of potash, enough, if all the constituents in it are used, to grow nearly 70 bushels of wheat with the accompanying straw. These have come from the farm somewhere; if they are not returned the power of the soil is lessened.

If the farmer wished to return these in the form of commercial fertilizers, he would have to pay out $30 at present prices--20 cents per pound for the nitrogen and four and a half cents each for the phosphoric acid and potash.

The following table shows the amount of fertility marketed with each one thousand dollars' worth of certain farm products, the fertilizers being reckoned at going prices. As prices vary with locality and year, the figures are merely approximate.

There is no waste on the farm which is so wanton, so inexcusable, as the too common waste of stable and barnyard manure.--A. M. Teneyck.

The real cash value of manure is not given proper consideration by most farmers. At ordinary commercial prices the nitrogen contained in the air above each acre is worth more than ten million dollars. By means of bacteria which live on their roots, clover, and other legumes have power to draw on this unlimited supply of free nitrogen.--C. H. Hopkins.