Understanding the yield impacts of alternative cover crop families and mixtures: Evidence from side-by-side plot-level panel data

Authors: WON, SUNJAE - Auburn University; REJESUS, RODERICK - North Carolina State University; PONCET, AURELIE - University Of Arkansas; AGLASAN, SERKAN - University Of Arizona; THAPA, RESHAM - Tennessee State University; TULLY, KATHERINE - University Of Maryland; REBERG-HORTON, S. CHRIS - North Carolina State University; CABRERA, MIGUEL - University Of Georgia; DAVIS, BRIAN - North Carolina State University; GASKIN, JULIA - University Of Georgia; HITCHCOCK, RICHARD - North Carolina State University; Schomberg, Harry; SEEHAVER, SARAH - North Carolina State University; Balkcom, Kipling; REITER, MARK - Virginia Tech; MILLER, JARROD - University Of Delaware; Mirsky, Steven

Submitted to: Agrosystems, Geosciences & Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/26/2024
Publication Date: 12/13/2024
Citation: Won, S., Rejesus, R., Poncet, A.M., Aglasan, S., Thapa, R., Tully, K.L., Reberg-Horton, S., Cabrera, M.L., Davis, B.W., Gaskin, J., Hitchcock, R., Schomberg, H.H., Seehaver, S.A., Balkcom, K.S., Reiter, M., Miller, J.O., Mirsky, S.B. 2024. Understanding the yield impacts of alternative cover crop families and mixtures: Evidence from side-by-side plot-level panel data. Agrosystems, Geosciences & Environment. 7:e70012. https://doi.org/10.1002/agg2.70012.
DOI: https://doi.org/10.1002/agg2.70012

Interpretive Summary: The literature is unclear as whether short-term effects of cover crop use on corn and soybean yield is good, neutral, or bad. There are a lot of factors that can affect cover crop impact on a following cash crop including which cover crop is used, how the cover crop is managed, and the weather. This multi-site field study examined the short-term effect of cover crop families (grasses like cereal rye, broadleaf species like oilseed radish, and legumes like hairy vetch) both when the cover crops were planted alone and as mixtures on cash crop yield in the Eastern US. The majority of the cover crop families and mixtures investigated in this study did not have a statistically significant short-term effect on subsequent corn yields. In some cases, cover crop treatment did result in short-run yield losses (i.e., a yield penalty). These results imply that cash crop yield benefits from cover crop adoption are likely not going to be observed with just one year of cover crop use. This lack of immediate economic benefit may explain the relatively low cover crop adoption rate currently observed in the US. It points to the need for upfront cost-share subsidy payments to support farmers who are encouraged to adopt this practice for the environmental benefits (e.g., reduced soil erosion) that it confers.

Technical Abstract: The short-run effects of cover crop use on cash crop yields (e.g., corn (Zea mays L.), soybeans (Glycine max (L.) Merr.) have been a topic of debate given that evidence from previous literature has generally been mixed on this issue. Past studies suggest that the observed yield effect varies (i.e., negative, positive, or insignificant), often depending on the applied cover crop species used, weather conditions, and farm management practices implemented (among others). In this study, we examine the short-run (i.e., one-year) yield impact of four different cover crop families — grasses (Poaceae), broadleaves (Brassica), legumes (Fabaceae), and others — both as single-family groups and as mixtures. Data from side-by-side on-farm experimental plots in six Eastern US States were collected from 2017 to 2019 in order to achieve the objective of the study. Statistical analysis of this multi-year plot-level data suggests that the majority of the cover crop families and mixtures investigated in this study do not have a statistically significant short-run effect on subsequent corn yields. In some cases, cover crop treatment even resulted in short-run yield losses (i.e., a yield penalty). These results imply that cash crop yield benefits from cover crop adoption are likely not going to be observed with just one year of use. This lack of immediate economic benefit may explain the relatively low cover crop adoption rate currently observed in the United States (US), and the need for upfront cost-share subsidy payments to encourage further uptake of this practice.