Every plant being composed of certain chemical elements, requires for its perfection a soil containing those elements. Thus chemistry has shown, by exact analysis, that good meadow hay contains the following elements: Silica (sand), lime (as a phosphate, a sulphate, and a carbonate, i. e. lime combined with phosphoric, sulphuric, and carbonic acids), potash (as a chloride, and a sulphate), magnesia, iron, and soda. Whatever soil is rich in these will be productive of grass.
The grain of wheat (in distinction from the straw) contains, and of course requires from the soil, sulphates of potash, soda, lime, magnesia, iron, etc.
Any vegetable, in its proper latitude, will flourish in a soil which will yield it an abundance of food; and decline in a soil which is barren of the proper nutritive ingredients.
A practical, scientific knowledge of these fundamental facts, will give an intelligent farmer, in grain-growing latitudes, almost unlimited power over his crops. A good cook knows what things are required for bread; he selects these materials, compounds them to definite proportions—adding, if any one is deficient; subtracting, if any one is in excess. Raising a crop is a species of slow cooking. Here is a compound of such materials (called wheat) to be made. Nature agrees to knead them together, and produce the grain, if the farmer will supply the materials. To do this he _must_ understand what these materials are. Suppose a cook perceiving that the bread was wretched, did not know exactly what was the matter; and should add, salt, or flour, or yeast, or water at hap-hazard? Yet that is exactly what multitudes of farmers do. They find that their fields yield a small crop of wheat. They do not know what the matter is. Is the soil deficient in lime, or sand, or clay? Is magnesia or potash lacking? Perhaps they do not even know that these things are requisite to this crop. “The land must be manured.” Now, manure on an impracticable soil, is _medicine_. Of course if the farmer prescribes, he must tell _what_ medicine, i. e. what manure. Is it vegetable matter or phosphates? alumina or silica? Suppose a doctor says: “You are sick and must take medicine,” without knowing what the disease is, or what the appropriate remedy; and so should pull out a handful of whatever there was in his saddle-bags and dose the wretch? That’s the way farming goes on. “The ten acre lot wants manure.” To the barn yard he goes, takes the dung heap, plows it under, and gets an enormous crop of—straw. Nitrogenous manure was not what the soil wanted. He has added materials which existed in abundance already; but those elements, from the want of which his crop suffered, have not been given it. The land is sicker than it was before. It languishes for want of one element, it suffers from a surfeit of another. We are prepared to sustain these observations by a reference to authentic facts.