Crop production and soil strength were evaluated indifferent cover crop management systems on a Norfolk sandy loan soil in 1989 and 1991. Treatments in the study were winter cover [vetch, rye, and fallow (winter weeds)], tillage, and date of incorporation/desiccation (5 or 15 days before planting) of the winter cover. Tillage treatments were conventional (discing, shallow harrowing, subsoiling at planting) and conservation (subsoiling at planting only). cover treatments were desiccated with paraquat in the conservation tillage treatment plots. Experimental design was randomized complete block in split-split plot arrangement with four replicates. Main plots were winter cover, subplots were tillage, and sub-subplots were incorporation/desiccation date.

Soil moisture and soil strength were measured to a depth of 60 cm about two weeks after planting in only the vetch and winter fallow plots each year. Soil moisture was measured in the row and in the mid-row. Soil strength was measured at nine places from mid-row to mid-row.

Soil moisture was not influenced by the treatments either year. Significant cover X tillage X incorporation/desiccation date interactions occurred for soil strength each year, but the nature of the interaction was different in 1991 compared to 1989. In 1991, soil strength was 0.2 MPa higher in the vetch plots than in the winter fallow plots, even though soil moisture was essentially the same in each treatment. Inspection of plotted data showed that in-row soil strength was similar between vetch and fallow (probably due to subsoiling at planting) but strength was greater in the vetch plots in the mid-rows.

Neither cover, tillage, nor date of incorporation/desiccation influenced cotton populations or seed cotton yield in 1989; in 1991, date of incorporation/ desiccation had no effect on populations or yield. Highest yield was obtained in the rye cover crop plots in 1991, and there was no difference between conventional and conservation tillage in that winter cover plots had lower yields for conservation tillage than conventional tillage. Poorer weed control in the conservation tillage plots in those two winter cover treatments was correlated with the yield decrease. Weed populations were similar between conservation and conventional tillage in the rye winter cover plots.