Broccoli production in cowpea, soybean, and velvetbean cover crop mulches

Fall transplanted 'Commander' broccoli (Brassica oleracea Botrytis group) yield in mulches formed from the residues of killed cowpea (Vigna unquiculata), soybean (Glycine max), and velvetbean (Mucuna pruriens) cover crops was compared to yield in conventional production on bare soil. Average aboveground biomass production was 6.9, 7.7, and 5.9 t.ha(-1) (3.08, 3.43, and 2.63 tons/acre) and total nitrogen content of the aboveground tissues was 2.9%, 2.8%, and 2.7% of the dry weight for cowpea, soybean, and velvetbean, respectively. Within each cover crop mulch main plot, subplots received different nitrogen rates, 0, 84.1, or 168.1 kg.ha(-1) (0, 75, or 150 lb/acre). For several nitrogen level x year comparisons, broccoli grown in mulched plots yielded higher than broccoli grown on bare soil plots. Cowpea and soybean mulches promoted broccoli growth more than velvetbean mulch. The mulches of all three species persisted through the growing season and suppressed annual weeds.