Green Manuring : Principles And Practice

TGS Survival Books Reprint: AGRICULTURE has been, and as far as can now be foreseen, always will be, the basic industry of the human race. Men must be fed even though they have to do without luxuries. Some recent writers have viewed the race between population increase and food supplies with alarm; others have voiced the thoughtless optimism of ignorance. Neither extreme view is warranted.

From the Author:

Mankind will adjust itself to new conditions as they arise, but in order to do so with the least suffering, it is necessary that every avenue of approach to the problem of maintaining or increasing the productive power of the soil be investigated. It is because the writer is strongly of the opinion that the practice of green manuring is one of these avenues, and an important one, that he has been glad of the opportunity to bring together what is known about green manuring.

The writer is a compiler rather than an original worker in this field, but if his efforts shall result in fostering some interest among those in charge of agricultural research, he will feel well repaid. The future of our country depends first upon an adequate supply of food, and no other body of men has so much need for long vision as those entrusted with the duty of making certain that the generations of the twenty-first century shall not go hungry.

The value of green manuring lies in the fact that organic matter is worked into the soil and the organic matter in soil is recognized as being one of its most valuable constituents. The soil nitrogen is associated with the organic matter and the decay of this organic matter influences the availability of the soil minerals. For these reasons, it has seemed advisable to discuss the amount of organic matter in soils, its source, and the influences which operate for the destruction of or the increase of organic matter, as well as the part it plays in the soil. Such a discussion is a necessary preliminary to the study of green manuring.

EXCERPT

GREEN manuring has been an agricultural practice among European farmers for more than two thousand years, but not until the nineteenth century did students of agriculture become interested in the processes by which plant material turned under became available for subsequent crops. Most of our scientific knowledge of plant nutrition, of the microörganisms of the soil, and of their importance in soil fertility has accumulated during the nineteenth and twentieth centuries.

It was during the nineteenth century, too, that the tremendous expansion of world food supplies took place, so that the available food of the world increased more rapidly than the population, and seemed to many to prove the fallacy of the Malthusian doctrine. In passing, attention may be called to the fact that "the law of Malthus has been often repudiated but never refuted."

Recent writers have made it clear that the end of this rapid expansion of food supplies is not far off, if indeed, the peak has not already been reached, and that it is time for men to take thought of the situation and consider what may be done to provide for an ever-increasing population. In the United States practically all of the good land, land that merely requires a reasonable rotation to maintain yields, is already in use and cannot be depended on for very large increases.

Many millions of acres of the poorer lands are either not in use or yield small returns, and it is by increasing the yields of these poorer lands that we must look for a part of the increased food supplies this country will use within the next fifty years.

Food Supply and Population.

-The general problem of the relation between food supply and population has various phases, some of the more important of which are production, transportation, economics of marketing, and control of population increase. A century ago, transportation was relatively more important than production. There was often famine in one region and plenty of food in another, but with no means of bringing the food to the hungry. Today transportation, except as a part of the economics of marketing, is not of such great importance, since that part of the general problem has been solved, and at present the economics of marketing is receiving most attention. Farmers, especially in the United States, find it, at present, not difficult to produce more than the market will absorb. Production is, however, the fundamental problem and it is a safe prediction that in a hundred years the production of more food per acre, and the utilization of every acre of land will be matters of concern.

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