Evaluation of Cover Crops Drill Interseeded into Corn Across the Mid‐Atlantic Region

CORE IDEAS: Cover crops were successfully established in corn with a drill interseeder.Cover crop biomass production varied notably across the mid‐Atlantic region.Spring cover crop biomass was often proportional to fall cover crop performance.Interseeding cover crops at corn growth stages V2–V3 decreased corn grain yields.Interseeding cover crops at or after corn V4 did not affect corn grain yield. Cover crop adoption remains low in the mid‐Atlantic United States despite potential conservation and production benefits. The short growing season window after corn (Zea mays L.) is a primary limiting factor. A high‐clearance grain drill was recently developed to allow for cover crop interseeding into standing cash crops. Experiment 1 tested the viability of drill interseeding cover crops into corn at the V5 growth stage across multiple locations. Experiment 2 tested interseeding timing (V2–V6 corn growth stage) on corn yield in Pennsylvania. At 16 locations throughout Maryland, Pennsylvania, and New York, we evaluated cover crop fall and spring biomass and the effect on corn yield. Cover crop treatments included annual ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot]), a mixture of legume species, and an annual ryegrass–legume mixture. Each cover crop treatment successfully established across locations yet was highly variable. Across locations, annual ryegrass–legume mixture produced the highest mean aboveground biomass in fall and spring. Spring biomass of interseeded cover crops generally increased compared with fall biomass. Interseeded cover crops did not affect grain yields of the host corn crop during the year of establishment across locations. Experiment 2 indicated that cover crops interseeded before the V3 growth stage reduced corn grain yields. We recommend interseeding at or after V4 to prevent competition with corn. Our results highlight the viability of drill‐interseeding as a strategy for increasing cover crop adoption.