Benefits of vetch and rye cover crops to sweet corn under no-tillage
Leguminous cover crops (CCs) may reduce N fertilizer requirements by fixing N biologically and storing leftover N-fertilizer applied in the previous year. The objective of this study was to determine the contribution of CCs [rye (Secale cereal L.) and hairy vetch (Vicia villosa Roth)] on plant N nutrition and weed suppression to the following sweet corn (Zea mays L.). The CCs were planted in the fall of 2003 and 2005, and sweet corn was planted in spring of 2004 and 2006. The experiment contained N rates and CC treatments. In 2004, two CC treatments were tested: none and a CC mixture consisting of 67% rye and 33% hairy vetch. In 2006 the experiment contained five CC treatments (100% rye; 100% vetch; 67% rye and 33% vetch; 33% rye and 67% vetch; and none). Nitrogen rates of 0, 67, and 133 kg ha–1 were split-applied at emergence, V3–4, and V9–10 growth stages. Two additional plots under non-CC treatment received N rates of 200 or 267 kg ha–1 to develop a N response curve. Sweet corn growth, N-accumulation, and yield were increased when CCs were presented for low-fertilizer inputs. The N contribution of CC to the sweet corn ranged between 35 and 75 kg ha–1. Yield response to N-fertilizer application was fitted in a cubic model with optimum yield of 22 Mg ha–1 attained with 230 kg N ha–1. Rye reduced weed biomass by 25% and 36% compared with non-CC and vetch. In conclusion, the potential CC yield benefits to sweet corn were greatest at lowest supplemental N rates.