other hand, potassium has a tendency to prolong the growth of crops, but its chief office is increasing the yield or quantity of fruit. Consequently, when the yield is small, you may conclude there is a deficiency of either phosphorus or potassium-or both-in the soil.

And again if you observe that your plants are of rich, green color and of good size, you may be sure they are not in need of nitrogen. If, however, they are small and pale and sickly in appearance, you may know that nitrogen is sorely in need.

Nitrogen is the most costly element of plant food we buy, and for this reason we should depend upon homemade manures and the various legumes for every bit of nitrogen that is needed on the farm. Of course, we cannot get our phosphorus and potassium in that way. These come from the soil and not from the air; hence, a deficiency in either must come through some artificial

means.

Sources of nitrogen.-While nitrogen is one of the most abundant of substances, just the same, it is one of the easiest lost and used up in the soil. In buying nitrogen as a fertilizer, you must seek a material already having it in combination. In combination with the element hydrogen (which is a constituent of water) ammonia is formed, and a gas it is, also; and it is very soluble in water. The pungent odor of ammonia water is due to ammonia gas. Thus we get the same odor in stables and fresh manure piles: ammonia gas is passing off into the air, later to be brought down by dew or rain, fertilizing, perhaps, some distant field.

Ammonia has a great fondness for sulphuric acid, and unites with it with vigor, giving rise to a substance white and solid, and known to fertilizer dealers and users as sulphate of ammonia,

The commercial sulphate of ammonia contains about twenty per cent. of nitrogen, or four hundred pounds of nitrogen to the ton. In this material the ammonia is held and is prevented from escaping by the sulphuric acid. Sulphate of ammonia is easily soluble in water, and distributes itself through the soil where plant roots can get at it. It adds to the nitrogen stores where come plant roots for the nitrogen necessary to their growth.

On account of the ease with which water dissolves it, sulphate of ammonia is one of our most valuable and

NITROGEN

NITRATE of SODA

SULPHATE of AMMONIAI

DRIED BLOOD

TANKAGE

FISH SCRAP

COTTON SEED MEAL

PHOSPHOROUS

ACID PHOSPHATE

GROUND BONE

DISSOLVED BONE

POTASSIUM

KAINIT

MURIATE of POTASH

SULPHATEofPOTASH

ASHES

OUR COMMON FERTILIZING MATERIALS

quickly acting sources of nitrogen for plants, but, at the same time, it is one of the most costly sources. It is not as readily washed out of soils as nitrate of soda.

The chief source of supply is at the gas factory, where it becomes a waste product in the manufacture of gas from soft coal, and in the production of coke from coal.

Nitrate of soda or chili saltpeter is a white solid material that is mined in the rainless districts of South America. As found there, it is mixed with other substances, but when purified, it is put on the market as" commercial nitrate of soda to be used as a chemical

manure for lands. When prepared for commercial use, it contains fifteen and one-half to sixteen per cent. of nitrogen, or 320 pounds to the ton. The remaining 1,680 pounds of the ton are the elements sodium and oxygen, to which the nitrogen is united, and these form the nitrate of soda. In addition to these, forty to sixty pounds of impurities mostly common salt-are present in each ton of the commercial product.

Nitrate of soda dissolves in water with great ease, and readily distributes itself in the soil. It is in this form that plants like most to use nitrogen, and it is in this form they take it up in greatest abundance: in no other does nitrogen act more quickly or show its effect more quickly when applied to the soil. So in two or three days after an application of the fertilizer is made, its effect is seen on growing plants. They show an increase in vigor, a deeper green color is seen, and greater activity in growth is apparent at once.

In this connection it might be worth your while to recall to mind this fact: nitrogen, in nearly every case, enters plants as a nitrate. Sulphate of ammonia, for instance, when used as a fertilizer, sometimes is acted upon by micro-organisms which change the ammonia form to the nitrate form. Of course, there is an objection when any large quantity of nitrates are present in the soil it is soluble, and soil water and drainage waters gather it up and carry it away-out of reach of plants, out into the sea, perhaps. A great quantity of nitrogen is lost in this way each year.

Dried blood contains from eight to twelve per cent. of nitrogen and from seven to fourteen per cent. of phosphoric acid, and is the richest substance coming from animal products.

When live stock is slaughtered, the blood is collected in

tanks and boiled that the albuminoids may be coagulated. The water of this material is then removed; the resulting materials are pressed into cake, and later broken, and dried, and ground-all operations essential in making the commercial product.

Tankage. This is a by-product of the slaughter-house and contains from four to eight per cent. of nitrogen and from seven to fourteen per cent. of phosphoric acid. It slowly decomposes in the soil, and is generally appreciated as a chemical fertilizer. Included in this product are intestines, lungs, tendons, bones, blood, and other refuse. After being cooked in tanks and pressed, it is dried and ground, and then is sent out as a fertilizer or as a feeding stuff for pigs.

Dried and ground fish-or dried fish scrap, as it is often called-is a by-product of the fish-oil and canning factories. Both nitrogen and phosphorus are contained in this product: from six to eight per cent. of the former, and from seven to nine per cent. of the latter. This byproduct is consumed largely by those near the sources of supply.

Cotton-seed meal.-Usually about seven per cent. of nitrogen, or one hundred and forty pounds to the ton, are found in this fertilizing material. It is by far the most important of the vegetable products used as commercial fertilizers. It decays somewhat rapidly, yet lasts long enough so that the growing crop may use it. It is more promptly available than tankage, but much less quickly available than either nitrate of soda or sulphate of ammonia.

Cotton-seed meal is a by-product of the cotton-oil mill. In removing the oil from cotton seed, the seed are cut into bits and cooked and pressed into cakes. These cakes are then ground into fine meal, which may be used either as

a feeding stuff or as a fertilizer. The amount of cottonseed meal used for fertilizing purposes is very large in the South. It is not economy, however; for a vegetable product so rich in protein as cotton-seed meal to be buried in the ground is poor economy and a waste of wealth. Cotton-seed meal ought first to be fed to live stock and the resulting manure returned to the land. When properly utilized in this way, both humus and available plant food will be secured, or a double profit; a profit from the meal as food, and a profit from it as a fertilizer.

Sources of phosphorus.-Phosphorus cannot be used as a fertilizer in a free state, for the reason it readily

WHERE ACID PHOSPHATE PAYS

Every man who uses chemical manures ought to test his land

takes fire. Consequently, when used for commercial purposes it always is found in combination with lime, iron, or some similar substance present in the soil.

A combination of this sort gives rise to what is known as phosphate. Phosphate of lime, for instance, constitutes the main portion of bone and the various phosphate rocks mined in North and South Carolina, in Tennessee in