Cover crop biomass production across establishment methods in Mid-Atlantic corn

Authors: MOORE, VIRGINIA - North Carolina State University; Mirsky, Steven

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/13/2020
Publication Date: 10/14/2020
Citation: Moore, V., Mirsky, S.B. 2020. Cover crop biomass production across establishment methods in Mid-Atlantic corn. Agronomy Journal. 112(6):4765-4774. https://doi.org/10.1002/agj2.20414.
DOI: https://doi.org/10.1002/agj2.20414

Interpretive Summary: Cover crops are typically planted in the fall after cash crops like corn and soybean are harvested. However, this leaves a narrow window for the cover crops to establish and grow before the onset of winter, and late establishment can limit the benefits provided by cover crops (e.g., improved soil and water quality). Some farmers instead broadcast cover crops in late summer into standing cash crops or plant cover crops in early summer between cash crops using specialized drills, or “interseeders". Each of these cover crop planting methods has a different set of risks, and results can be unpredictable. In this experiment, we tested several cover crop species and mixtures using each of the planting methods over three growing seasons. We observed complex interactions, with the success of each method depending on establishment timing, weather conditions, and the cover crop species being planted. These results highlight the need for more research on the complex genotype x environment x management interactions in these cover crop systems, and to establish risks and best management practices for different cover crop establishment methods. This work will be used to inform future research as well as farmers on cover crop management.

Technical Abstract: Drill-interseeding, broadcast-interseeding, and post-harvest drilling for establishment of overwintering cover crops after no-till corn (Zea mays L.) each present distinct challenges and benefits. Experiments were conducted at the Beltsville Agricultural Research Center (Maryland, USA) across three growing seasons (2013-2014, 2014-2015, 2015-2016), to evaluate the relative performance of these three establishment methods across four cover crop treatments: (1) cereal rye (Secale cereale L.), (2) annual ryegrass (Lolium perenne L. ssp. multiflorum (Lam.) Husnot), (3) a legume mixture including red clover (Trifolium pratense L.), crimson clover (Trifolium incarnatum L.), and hairy vetch (Vicia villosa Roth), and (4) a grass-legume mixture including annual ryegrass, red clover, crimson clover, and hairy vetch. Both fall and spring biomass showed a significant three-way interaction effect between cover crop, establishment method, and year. In 2015-2016, delayed planting of the drill-interseeded treatments resulted in poor performance in terms of both fall and spring biomass production. Also in 2015-2016, a dry period following planting of the broadcast-interseeded treatments resulted in poor fall biomass production. In 2014-2015, late planting of the post-harvest drilled treatments combined with harsh winter conditions resulted in poor fall and spring biomass production. Cereal rye appeared better able to withstand the stress associated with late post-harvest drilling, but did not perform as well as other cover crops in the interseeded-treatments. Our results highlight potential pitfalls of each establishment method, depending on annual variability in weather.