Evaluation of cover crops drill interseeded into corn across the mid-Atlantic region

Authors: CURRAN, WILLIAM - Pennsylvania State University; HOOVER, R - Pennsylvania State University; Mirsky, Steven; ROTH, GREG - Pennsylvania State University; RYAN, MATT - Cornell University; ACKROYD, VICTORIA - University Of Maryland; WALLACE, JOHN - Pennsylvania State University; DEMPSEY, MARK - Pennsylvania State University; PELZER, CHRIS - Cornell University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2017
Publication Date: 3/1/2018
Citation: Curran, W.S., Hoover, R.J., Mirsky, S.B., Roth, G.W., Ryan, M.R., Ackroyd, V.J., Wallace, J.M., Dempsey, M.A., Pelzer, C.J. 2018. Evaluation of cover crops drill interseeded into corn across the mid-Atlantic region. Agronomy Journal. 110:435-443. https://doi.org/10.2134/agronj2017.07.0395.
DOI: https://doi.org/10.2134/agronj2017.07.0395

Interpretive Summary: Cover crops are crops that are generally not planted to be harvested and sold, but rather because they benefit farms in other ways (e.g., by improving soil health and decreasing soil erosion over the winter). In spite of the many well-documented benefits of cover crop use, relatively few farmers in the mid-Atlantic region plant cover crops because there is too little time to establish cover crops after corn harvest before the onset of winter. An alternative to planting cover crops in the fall is to interseed them into the corn while it is still growing. The cover crops germinate and grow, then go dormant when the corn canopy shades them. As soon as the corn is harvested, the cover crops take advantage of the sunlight to grow prior to winter. We conducted an experiment in New York, Pennsylvania, and Maryland to evaluate the growth of cover crops interseeded at corn growth stage V5 (when corn is less than knee-high) and determine cover crop impact on corn yield. The cover crops tested were annual ryegrass, a mixture of legume species, and an annual ryegrass-legume mixture. Each cover crop treatment successfully established across locations, but fall and spring biomass production was highly variable. Across locations, the annual ryegrass-legume mixture produced the most biomass in fall and spring. In general, the more biomass a cover crop produced in the fall, the more biomass was present in spring. Interseeded cover crops did not affect grain yields of the host corn crop. We also conducted a supplemental field experiment to determine the effect of interseeding timing (V2 to V6 corn growth stage) on yields of the host corn crop in Pennsylvania. This supplemental experiment indicated that cover crops interseeded before the V4 growth stage reduced corn grain yields, but interseeding at or after V4 had no effect. Our results highlight the viability of drill-interseeding as strategy for increasing cover crop adoption and suggest that farmers should interseed cover crops at or after corn growth stage V4 to avoid decreased corn yield. This information will be useful to scientists devising strategies to integrate cover crops into crop production systems.

Technical Abstract: Cover crop adoption remains low in the mid-Atlantic region despite the potential conservation and production benefits. The short growing season window after corn (Zea mays L.), is a primary factor limiting cover crop adoption in these regions. A high-clearance grain drill has been developed to allow for cover crop interseeding into standing cash crops. The objective of this experiment was to test the viability of drill interseeding cover crops into corn at the V5 growth stage. We evaluated cover crop fall and spring biomass and the effect on corn yield at sixteen sites throughout Maryland, Pennsylvania, and New York. Cover crop treatments included an annual ryegrass [Lolium perenne L. ssp. multiflorum (Lam.) Husnot]) monoculture, a mixture of legume species, and an annual ryegrass-legume mixture. Each cover crop treatment successfully established across locations, but fall and spring biomass production was highly variable. Across locations, the annual ryegrass-legume mixture produced the highest mean biomass in fall and spring. Spring biomass of interseeded cover crops was influenced by fall biomass. Interseeded cover crops did not affect grain yields of the host corn crop across mid-Atlantic locations. We also conducted a 2-year supplemental field experiment to determine the effect of interseeding timing (V2 to V6 corn growth stage), on yields of the host corn crop in Pennsylvania. This supplemental experiment indicated that cover crops interseeded before the V4 growth stage reduced corn grain yields, but interseeding at or after V4 had no effect. Our results highlight the viability of drill-interseeding as strategy for increasing cover crop adoption.