Evaluation of interseeding cover crop mixtures in Mid‐Atlantic double‐crop soybean

Abstract

AbstractWinter legume cover crops can provide organic nitrogen (N) to the subsequent corn (Zea mays L.) crop. However, legume cover crop adoption is limited in the Mid‐Atlantic United States by the short establishment window after double‐crop soybean [Glycine max (L.) Merr.] harvest. Interseeding legume cover crops into double‐crop soybean with a modified seed drill could improve on previous interseeding methods. We conducted field trials in which four cereal rye (Secale cereale L.) + legume mixtures were interseeded into double‐crop soybean on 76‐cm row spacing. Double‐crop soybean yield was compared between the 76‐cm row spacing required for interseeding and the more common 38‐cm row spacing. Overall, there was minimal effect of row spacing or interseeding on double‐crop soybean yield. Cover crop biomass varied by species, ranging from 1 to 7 Mg ha–1. Cover crop biomass N content was higher in cereal rye + legume treatments (mean, 79 kg N ha–1) than in cereal rye alone (mean, 30 kg N ha–1; p < .001). We also examined the effect of fall‐interseeded cover crop mixtures on corn yield. Corn yields were low in 2018, yet we observed higher corn yields in the cereal rye + hairy vetch (Vicia villosa Roth) cover crop compared with no cover crop and cereal rye alone. In 2019, there was no effect of cover crops on corn yields. This study demonstrated the specific benefits of integrating legumes into cropping rotations, namely increased N cycling efficiency and resiliency to extreme weather patterns.