The chief reluctance to accept clean summer fallowing as a principle of dry-farming appears chicfly among students of the Great Plains area.  Even there it is admitted by all that a wheat crop following a fallow year is larger and better than one following wheat.  There seem, however, to be two serious reasons for objecting to it.  First, a fear that a clean summer fallow, practiced every second, third, or fourth year, will cause a large diminution of the organic matter in the soil, resulting finally in complete crop failure; and second, a belief that a hoed crop, like corn or potatoes, exerts the same beneficial effect.

It is undoubtedly true that the thorough tillage involved in dry-farming exposes to the action of the elements the organic matter of the soil and thereby favors rapid oxidation.  For that reason the different ways in which organic matter may be supplied regularly to dry-farms are pointed out in Chapter XIV.  It may also be observed that the header harvesting system employed over a large part of the dry-farm territory leaves the large header stubble to be plowed under, and it is probable that under such methods more organic matter is added to the soil during the year of cropping than is lost during the year of fallowing.  It may, moreover, be observed that thorough tillage of a crop like corn or potatoes tends to cause a loss of the organic matter of the soil to a degree nearly as large as is the case when a fallow field is well cultivated.  The thorough stirring of the soil under an arid or semiarid climate, which is an essential feature of dry-farming, will always result in a decrease in organic matter.  It matters little whether the soil is fallow or in crop during the process of cultivation, so far as the result is concerned.

A serious matter connected with fallowing in the Great Plains area is the blowing of the loose well-tilled soil of the fallow fields, which results from the heavy winds that blow so steadily over a large part of the western slope of the Mississippi Valley.  This is largely avoided when crops are grown on the land, even when it is well tilled.

The theory, recently proposed, that in the Great Plains area, where the rains come chicfly in summer, the growing of hoed crops may take the place of the summer fallow, is said to be based on experimental data not yet published.  Careful and conscientious experimenters, as Chilcott and his co-laborers, indicate in their statements that in many cases the yields of wheat, after a hoed crop, have been larger than after a fallow year.  The doctrine has, therefore, been rather widely disseminated that fallowing has no place in the dry-farming of the Great Plains area and should be replaced by the growing of hoed crops.  Chilcott, who is the chief exponent of this doctrine, declares, however, that it is only with spring-grown crops and for a succession of normal years that fallowing may be omitted, and that fallowing must be resorted to