Submitted to: HortTechnology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 6/4/2004
Publication Date: 12/15/2004
Citation: Harrison Jr, H.F., Jackson, D.M., Keinath, A.P., Pullaro, T.C., Marino, P.C. 2004. Comparison of cowpea, soybean and velvetbean cover crop mulches for broccoli production. HortTechnology 14:484-487. Interpretive Summary: Studies were conducted to compare cowpea, soybean and velvetleaf cover crops for use in a broccoli production system where the crop residues were left on the soil surface to provide a mulch. Broccoli grew faster and yielded more in cowpea and soybean mulches than in bare soil conventional production at low nitrogen fertilization. Velvetbean mulch did not appear to promote broccoli growth and yield as well as cowpea or soybean mulches. All three cover crop mulches persisted through the growing season and provided effective suppression of annual weeds. The major benefits of the cover crop mulches were weed suppression and providing nitrogen. These benefits may reduce the environmental impact of broccoli production by reducing herbicide and nitrogen fertilizer inputs.
Technical Abstract: Fall transplanted 'Commander' broccoli (Brassica oleracea L. Botrytis group) was grown on mulches made of the killed residues of cowpea (Vigna unquiculata (L) Walp.), soybean (Glycine max (L.) Merr.) and velvetbean (Mucuna pruriens L DC.) cover crops. Cover crop species were the main plot treatments in a split plot design where three nitrogen rates (0, 84 and 168 kg ha-1) were subplot treatments. Average biomass production was 6.9, 7.7 and 5.9 t dry matter ha-1 and total nitrogen contents for the above ground tissues were 2.9, 2.8 and 2.7% of dry weight for cowpea, soybean and velvetbean, respectively. Broccoli yields were higher in the cover crop mulches than in the bare ground controls, particularly at the 0 and 83 kg ha-1 nitrogen rates. In general, cowpea and soybean mulches appeared to promote broccoli growth and production more than velvetbean mulch. The mulches of all three legume species persisted through the growing season and provided good suppression of annual weeds.