Nitrogen Contribution from Winter‐Killed Faba Bean Cover Crop to Spring‐Sown Sweet Corn in Conventional and No‐Till Systems

Abstract

Core Ideas Faba bean cover crops sown on 1 August accumulated up to 192 kg N ha–1.Better synchrony between faba bean residue decomposition and N uptake by sweet corn was achieved under NT management.Sweet corn yielded higher under NT vs. CT system.On average, faba bean provided approximately 50 kg ha–1 of subsequent sweet corn N requirements. The N release trend of winter‐killed faba bean (Vicia faba L.) residues has not been previously investigated. A 2‐yr experiment was conducted in 2013–2015 to investigate potential N accumulation in fall‐grown faba bean as cover crop and N contribution to subsequent sweet corn under no‐till (NT) and conventional tillage (CT) systems. Faba bean biomass prior to winter‐kill was reduced linearly with delayed planting. The amount of reduced biomass estimated approximately 180 and 210 kg ha−1 d−1 in 2013 and 2014, respectively. Faba bean sown on 1 August accumulated as much as 192 kg N ha−1 vs. 67 kg N ha−1 when planted on 14 August. Under CT, 50% of N was released from residues by the end of May however NT system delayed 50% N release until end of June, thus providing better synchrony with N uptake by sweet corn. Averaged over two years, sweet corn planted into the residues of the earliest sown faba bean produced 19% more marketable ears, 23% higher fresh ear weight, and 39% less unfilled ear tip compared with sweet corn grown in plots lacking a prior faba bean cover crop. Both number of marketable ears and fresh ear yield of sweet corn were significantly higher in NT compared with CT systems. On average, sweet corn seeded in faba bean residues and amended with an additional 50 kg N ha−1, yielded similarly to sweet corn received 100 kg N ha−1 with no prior faba bean cover crop.