tailieunhanh - DRY-FARM SOILS

Important as is the rainfall in making dry-farming successful, it is not more so than the soils of the dry-farms. On a shallow soil, or on one penetrated with gravel streaks, crop failures are probable even under a large rainfall; but a deep soil of uniform texture, unbroken by gravel or hardpan, in which much water may be stored, and which furnishes also an abundance of feeding space for the roots, will yield large crops even under a very small rainfall. Likewise, an infertile soil, though it be deep, and under a large precipitation, cannot be depended on for. | DRY-FARM SOILS Important as is the rainfall in making dry-farming successful it is not more so than the soils of the dry-farms. On a shallow soil or on one penetrated with gravel streaks crop failures are probable even under a large rainfall but a deep soil of uniform texture unbroken by gravel or hardpan in which much water may be stored and which furnishes also an abundance of feeding space for the roots will yield large crops even under a very small rainfall. Likewise an infertile soil though it be deep and under a large precipitation cannot be depended on for good crops but a fertile soil though not quite so deep nor under so large a rainfall will almost invariably bring large crops to maturity. A correct understanding of the soil from the surface to a depth of ten feet is almost indispensable before a safe Judgment can be pronounced upon the full dry-farm possibilities of a district. Especially is it necessary to know a the depth b the uniformity of structure and c the relative fertility of the soil in order to plan an intelligent system of farming that will be rationally adapted to the rainfall and other climatic factors. It is a matter of regret that so much of our information concerning the soils of the dry-farm territory of the United States and other countries has been obtained according to the methods and for the needs of humid countries and that therefore the special knowledge of our arid and semiarid soils needed for the development of dry-farming is small and fragmentary. What is known to-day concerning the nature of arid soils and their relation to cultural processes under a scanty rainfall is due very largely to the extensive researches and voluminous writings of Dr. E. W. Hilgard who for a generation was in charge of the agricultural work of the state of California. Future students of arid soils must of necessity rest their investigations upon the pioneer work done by Dr. Hilgard. The contents of this chapter are in a large part gathered from .