Faba Bean Cover Crop Residues Decomposition Trend and Nitrogen Needs of Sweet Corn.

Legume cover crops have great potential for providing substantial amount of nitrogen when their residues are decomposed. However due to low C:N ratio, nitrogen release from legume cover crop residues may not be well synchronized with crops’ need. Faba bean (Vicia faba L.) is a cool season legume that can be grown as cash crop while it continues growing and serve as late fall cover crop. A split-plot design experiment was conducted to study the quantity and synchrony of nitrogen release by faba bean residues with following sweet corn. Main plots were consisted of conventional (CT) and no-till (NT) tillage systems whereas subplots assigned to five nitrogen rates (0, 25, 50, 75 and 100 kg N ha^-1) applied when sweet corn reached 25 cm height. Samples were taken for monitoring sweet corn biomass accumulation. Under CT, faba bean residues decomposed rapidly thus when sweet corn began its active growth; almost 65% of its original nitrogen was available to the growing crop. Under NT, nitrogen release was significantly slower where 50% of original nitrogen was still remained in the cover crop residues. Faba bean contribution to nitrogen need of sweet corn was estimated as much as 50 kg N ha^-1. Sweet corn planted into faba bean residues plus application of 50 kg N ha^-1 yielded as much as sweet corn that received 100 kg N ha^-1 with no cover crop.