ABSTRACT

Conventional tillage in the southeastern Coastal Plains usually includes disking to a depth of 0.15 to 0.20 m. Both conventional and conservation tillage include deep profile disruption to break up root-restricting, subsurface pans. Winter cover crops are often grown to prevent nutrient leaching by winter rains. However, winter cover crops can also dry the soil and make the pan even harder. Cotton (Gossypium hirsutum L. var Coker 315) was grown for two years in plots with or without a vetch (Vicia villosa Roth var. Cahaba white) cover crop. Plots were split into sections that were annually disked and bedded (conventional tillage) or non-disked (conservation tillage). Soil strength was 4.3% lower in the conventional tillage plots because of the loosening of the surface layer of the soil. Soil strength was 11.6% higher in the vetch cover crop plots. This higher strength was caused at least partially by dryer plots. Despite this, seed cotton yield was greatest in the conventional tillage, vetch cover crop plots (2161 kg/ha) and least in the conservation tillage, no-cover crop plots (1436 kg/ha). Higher yield in the conventional tillage plots is attributed to lower surface layer soil strength and better weed control. Higher yield in the vetch cover crops is probably a result of a rotational effect, increased infiltration, or better water holding capacities.