Cover crop species and cultivars for drill-interseeding in Mid-Atlantic corn and soybean

Authors: CASWELL, KATHERINE - Pennsylvania State University; WALLACE, JOHN - Pennsylvania State University; CURRAN, WILLIAM - Pennsylvania State University; Mirsky, Steven; RYAN, MATT - Cornell University

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/10/2019
Publication Date: 3/14/2019
Citation: Caswell, K., Wallace, J.M., Curran, W.S., Mirsky, S.B., Ryan, M.R. 2019. Cover crop species and cultivars for drill-interseeding in Mid-Atlantic corn and soybean. Agronomy Journal. 111(3):1060-1067.

Interpretive Summary: Cover crops are plant species grown not for harvest, but because they provide economic and environmental benefits to cropping systems. A legume cover crop such as clover can fix nitrogen, decreasing the amount of commercial fertilizer needed by following cash crop and thus fertilizer costs. Grass cover crops such as rye protect the soil from erosion and help prevent nutrients from leaving the cropping system, which decreases pollution of ground- and surface water (e.g., the Chesapeake Bay). In spite of the many benefits provided, relatively little acreage is planted to cover crops in the US. A major barrier to cover crop use is the lack of time after cash crop harvest to plant a cover crop before winter sets in. To work around this barrier, researchers are experimenting with interseeding cover crops into standing corn and soybean crops (i.e., before cash crop harvest). The cover crops sprout and grow, then go dormant once the cash crop begins to shade them. Once the cash crop is harvested, the cover crops respond to increased light levels by growing and becoming well-established before it freezes. Researchers are testing a variety of cover crops to see which grow best when interseeded. This study tested rye, hairy vetch, orchardgrass, several species of clover, and several cultivars of annual ryegrass interseeded into no-till corn or soybeans in Maryland, Pennsylvania, and New York. Cover crop performance was determined based on the amount of biomass (plant tissue) each species or cultivar produced in fall and spring. Annual ryegrass cultivars produced the same amount of biomass, suggesting farmers can choose the least expensive or most readily available cultivar. Annual ryegrass, orchardgrass, and medium red clover produced the most biomass among species tested in corn, suggesting these cover crops are good choices for farmers interseeding into corn. Annual ryegrass and medium red clover produced the most biomass among species tested in soybeans, suggesting these cover crops are good choices for interseeding into soybeans. Crimson clover produced similarly large fall biomass in corn and soybeans, but did not survive the winter as well as other species, making it a less ideal choice. This study provides guidance for farmers who want to interseed cover crops into corn and soybeans. This study also indicates the need to breed cover crops for traits that are beneficial when interseeding (e.g., shade tolerance) so that farmers have a wider range of choices based on cropping system goals and constraints.

Technical Abstract: Drill-interseeding is becoming a viable method for integrating cover crops in no-till corn (Zea mays L.) production in the Mid-Atlantic region. Development of best management practices for drill-interseeding cover crops into no-till grain crops requires greater understanding of cover crop performance at the species and cultivar levels. Experiments were conducted at multiple Mid-Atlantic locations (Maryland, Pennsylvania, New York) in two consecutive growing seasons (2013–2014, 2014–2015), to evaluate establishment and performance of drill-interseeded: (i) grass and legume cover crop species (n = 8) and annual ryegrass [Lolium perenne L. spp. multiflorum (Lam.) Husnot] cultivars (n = 10) in field corn, and (ii) grass and legume cover crop species (n = 6) in soybean [Glycine max (L.) Merr]. Fall biomass production of drill-interseeded cover crops was higher and less variable among locations in field corn than soybean. Annual ryegrass, orchardgrass (Dactylis glomerata L.), medium red clover (Trifolium pratense L.), and crimson clover (Trifolium incarntum L.), produced greater mean fall biomass than other species in field corn, but variable winter hardiness of crimson clover resulted in less spring biomass than alternative species. No differences were observed among annual ryegrass cultivars. Annual ryegrass, medium red clover, and crimson clover produced greater mean fall biomass than other species in soybean across locations. Our results highlight the viability of a narrow suite of cover crop species for interseeding in Mid-Atlantic no-till grain systems and point to the need for development of agronomic practices that facilitate greater niche complementarity between cover and cash crops.