As we have shown, clover can get more nitrogen out of the soil, than wheat, barley, and oats. And the same is true of beans and peas, though probably not to so great an extent.
Now, it would seem that Indian corn can get more nitrogen out of a soil, than wheat, barley, or oats—and to this extent, at least, we may consider Indian corn as a renovating crop. In other words, the Indian corn can get more nitrogen out of the soil, than wheat, barley, and oats—and when we feed out the corn and stalks on the farm, we have more food and more manure than if we raised and fed out a crop of oats, barley, or wheat. If this idea is correct, then Indian corn, when consumed on the farm, should not be classed with what the English farmers term “white crops,” but rather with the “green crops.” In other words, Indian corn is what old writers used to call a “fallow crop”—or what we call a renovating crop.
If this is so, then the growth and consumption of Indian corn on the farm, as is the case with clover, should leave the farm richer for wheat, rather than poorer. I do not mean richer absolutely, but richer so far as the available supply of plant-food is concerned.
“It may be that you are right,” said the Doctor, “when corn is grown for fodder, but not when grown for the grain. It is the formation of the seed which exhausts the soil.”
If I could be sure that it was true of corn-fodder, I should have little doubt that it is true also of corn as ordinarily grown for grain and stalks. For, I think, it is clear that the grain is formed at the expense of the stalks, and not directly from the soil. The corn-fodder will take from the soil as much nitrogen and phosphoric acid as the crop of corn, and the more it will take, the more it approximates in character to clover and other renovating crops. If corn-fodder is a renovating crop, so is the ordinary corn-crop, also, provided it is consumed on the farm.
“But what makes you think,” said the Deacon, “that corn can get more nitrogen from the soil, than wheat?”
“That is the real point, Deacon,” said I, “and I will ask you this question. Suppose you had a field of wheat seeded down to clover, and the clover failed. After harvest, you plow up half of the field and sow it to wheat again, the other half of the field you plow in the spring, and plant with Indian corn. Now, suppose you get 15 bushels of wheat to the acre, how much corn do you think you would be likely to get?”
“Well, that depends,” said the Deacon, “but I should expect at least 30 bushels of shelled corn per acre.”
“Exactly, and I think most farmers would tell you the same; you get twice as much corn and stalks to the acre as you would of wheat and straw. In other words, while the wheat cannot find more nitrogen than is necessary to produce 15 bushels of wheat and straw, the corn can find, and does find, take up, and organize, at least twice as much nitrogen as the wheat.”
If these are facts, then the remarks we have made in regard to the value of clover as a fertilizing crop, are applicable in some degree to Indian corn. To grow clover and sell it, will in the end impoverish the soil; to grow clover and feed it out, will enrich the land. And the same will be true of Indian corn. It will gather up nitrogen that the wheat-crop can not appropriate; and when the corn and stalks are fed out, some 90 per cent of the nitrogen will be left in the manure.