INFLUENCE OF ORCHARD SOIL MANAGEMENT UPON THE INFILTRATION OF WATER AND SOME RELATED PHYSICAL CHARACTERISTICS OF THE SOIL

Abstract

The ultimate effects of cultivation, broadly speaking, are to destroy soil structure and decrease permeability to water, finally leading to increased run-off and erosion. Management practices which least permit these effects, will best conserve soil and sustain agriculture. In an exptl. orchard, 3 different soil covers were compared: namely, continuous bluegrass and continuous alfalfa, torn up each spring, and a cover crop of rye seeded in the fall and one of millet seeded in the spring. The effects of 13 yrs. of such treatments upon the granule structure and moisture infiltration were measured. Different soil covers produce marked changes in organic content and in physical properties which alter the infiltration capacity and moisture status of the mantle. Cultivation in the fall and spring with an annual coyer crop of rye sown in the fall and millet in the spring permitted reduction in organic content, granule stability, and probable permeability, and more compact, easily dispersed surface layer with poorer infiltration and greater erosion and run-off. Alfalfa sod, harrowed only in spring, resulted in higher organic content, better structure, increased infiltration, and decreased run-off and erosion. A permanent bluegrass sod, harrowed each spring, resulted in the highest organic. content and the greatest structural stability and permeability in the surface 3-inch layer, with excellent infiltration and almost no run-off and erosion. The cumulative effects of these treatments from 1926 to 1940, resulted in a better moisture status in the entire soil mantle where perennial cover crops were used. There is a close correlation between changes brought about in the physical properties and the actual measurements of moisture infiltration, run-off, and moisture content of the entire profile. Exposure of soil to rainfall and drying during the fall and spring prepns., and the time required for the annual cover crops to become effective covers have resulted in physical deterioration as compared with conditions found under perennial covers.