Weed suppression by sunn hemp and sorghum cover crop

Abstract

The objective of this study was to evaluate the effect of green manure on weed suppression.The experiment was conducted at the Center for Agricultural Sciences / UFSCar, Araras, São Paulo, in randomized complete blocks using the species Crotalaria (Crotalaria spectabilis) and sorghum (Sorghum bicolor) and two management (corporate and superficial) with four replications. The importance value index (IVI) of spontaneous plants were obtained at 15, 30 and 45 days after cutting the biomass (DAC). To Crotalaria spectabilis incorporated the species Ipomoea triloba, Euphorbia heterophylla and C. echinatus showed high IVI. To crotalaria with the biomass at in surface, Cyperus rotundus was highlighted as the IVI. The treatment with Sorghum bicolor at 15 DAC,C. echinatus presented the IVI of 83.8 (biomass incorporated) and zero when the biomass was kept in the surface. As for C. rotundus, the biomass kept on the surface was not effective for suppression. It was concluded that although the green manures can be used in weed suppression, this depends on the weeds and green manure species, kind of management and amount of biomass.