Grass–Legume Mixtures and Soil Fertility Affect Cover Crop Performance and Weed Seed Production

• DOI: 10.1614/wt-d-10-00134.1
• Publication Date: 2011-08-16T19:33:53Z
• Authors: Daniel C. Brainard; Robin R. Bellinder; Virender Kumar
• Keywords: Monoculture

Summer leguminous cover crops can improve soil health and reduce the economic environmental costs associated with N fertilizers. However, adoption is often constrained by poor weed suppression compared to nonlegume crops. In field experiments conducted in organic vegetable cropping systems north-central New York, two primary hypotheses were tested: (1) mixtures of legume (cowpea soybean) grasses (sorghum–sudangrass Japanese millet) seed production increase crop productivity relative monocultures (2) higher fertility shifts competitive outcome favor weeds Cover grown either alone or grass–legume combinations without composted chicken manure. Under hot, dry conditions 2005, cowpea soybean severely suppressed monoculture sorghum–sudangrass mixtures, resulting low biomass, nodulation, high levels Powell amaranth (> 25,000 seeds m −2 ). more typical temperature rainfall 2006, millet stimulated biomass nodulation monoculture, but soybeans both grasses. Composted manure shifted competition at expense (2005), grass (2006), (2006). a complementary on-farm trial, 99%; however, common purslane hairy galinsoga produced sufficient (600 ) replenish existing seedbank. Results suggest that cowpeas lower costs, risk production; not compatible mixture; (3) future must be considered when determining optimal choices.