Crops and Methods for Soil Improvement

Nearly all profitable farming in this country is based upon the fundamental fact that our lands are storehouses of fertility, and that this reserve of power is essential to a successful agriculture. Most soils, no matter how unproductive their condition to-day, have natural strength that we take into account, either consciously or unconsciously. Some good farm methods came into use thousands of years ago. Experience led to their acceptance.

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They were adequate only because there was natural strength in the land. Nature stored plant-food in more or less inert form and, as availability has been gained, plants have grown. Our dependence continues.

Plant Constituents.-There are a few technical terms whose use cannot be evaded in the few chapters on the use of lime and fertilizers. A plant will not come to maturity unless it can obtain for its use combinations of ten chemical elements. Agricultural land and the air provide all these elements. If they were in abundance in available forms, there would be no serious soil fertility problem. Some of their names may not interest us. Six or seven of these elements are in such abundance that we do not consider them. A farmer may say that when a dairy cow has luxuriant blue-grass in June, and an abundance of pure water, her wants are fully met. He omits mention of the air because it is never lacking in the field. In the same way the land-owner may forget the necessity of any kind of plant-food in the soil except nitrogen, phosphoric acid, potash, and lime. Probably the lime is very rarely deficient as a food for plants, and will be considered later only as a means of making soils friendly to plant life.

Nitrogen, phosphoric acid, and potash are the three substances that may not be in available form in sufficient amount for a growing crop. The lack may be in all three, or in any two, or in any one, of these plant constituents. The natural strength of the soil includes the small percentage of these materials that may be available, and the relatively large stores that nature has placed in the land in inert form as a provision against waste.

The thin covering of the earth that is known as the soil is disintegrated rock, combined with organic matter. The original rock "weathered," undergoing physical and chemical change. A long period of time was required for this work, and for the mixing and shifting from place to place that have occurred. Organic matter has been a factor in the making of soils, and is in high degree a controlling one in their production of food.

Organic Matter.-Nature is resourceful and is constantly alert to repair the wastes and mistakes of man. We may gain fundamental truth about soil fertility through observance of her methods in restoring land to a fertile condition. Our best success comes only when we work with her. When a soil has been robbed by man, and has been abandoned on account of inability to produce a profitable crop, the first thing nature does is to produce a growth of weeds, bushes, briers, or aught else of which the soil chances to have the seeds. It is nature's effort to restore some organic matter-some humus-making material-to the nearly helpless land. Vegetable matter, rotting on and in the soil, is the life-giving principle. It unlocks a bit of the great store of inert mineral plant-food during its growth and its decay. It is a solvent. The mulch it provides favors the holding of moisture in the soil, and it promotes friendly bacterial action. The productive power of most farming land is proportionate to the amount of organic matter in it. The casual observer, passing by farms, notes the presence or absence of humus-making material by the color and structure of the soil, and safely infers corresponding fertility or poverty. Organic matter is the life of the soil.

A great percentage of the food consumed by Europe and the Americas continues to come out of nature's own stores in the soil, organic and inorganic, without any assistance by man except in respect to selection of seeds, planting, and tillage. The percentage grows less as the store of original supplies grows less and population increases. Our science has broadened as the need has grown greater. We have relatively few acres remaining in the United States that do not require intelligent treatment to insure an adequate supply of available plant-food. The total area that has fallen below the line of profitable productiveness is large. Other areas that never were highly productive must supplement the lands originally fertile in order that human needs may be met.