CROP RESIDUE AND ROOT EFFECTS ON SOIL COMPACTION

Abstract

The potential of an intact rye cover crop to reduce machine-induced compaction was the subject of this study.A randomized complete block field experiment was conducted in southwest Virginia in a fine, mixed, mesic, AquicAgriudolls and in a fine-loamy, mixed, mesic, Typic Hapludults. Three cover-cropped treatments and one fall-tilled fallowtreatment were analyzed. The treatments permitted investigation of the effects of a crop, the condition of the crop, and thecontribution of root reinforcement to the alteration of soil response to machine traffic. Effects resulting from three levels oftrafficone, three, and five passeswere investigated. Undisturbed soil core samples were analyzed to determine theeffects of machine traffic on dry bulk density, pore size distribution, and saturated hydraulic conductivity. Measurable soilresponse to machine traffic was limited to the uppermost 150 mm of the soil profile. Treatments that included a rye coverproduced samples with significantly lower dry bulk densities and higher noncapillary porosities than the bare soiltreatment for the soil surface layer (25-75 mm) following multiple machine passes. Soil compaction appeared to bereduced by the reinforcing effect of a network of undisturbed roots within the soil. There was no convincing evidence thatabove-ground biomass contributed directly to the reduction of machine-induced compaction effects.