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

The short-run effects of cover crop use on cash crop yields (e.g., corn [Zea mays L.] and 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., 1 year) yield impact of four different cover crop families—grasses (Poaceae), broadleaves (Brassicaceae), 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 1 year of use. This lack of immediate economic benefit may explain the relatively low cover crop adoption rate currently observed in the United States and the need for upfront cost-share subsidy payments to encourage further uptake of this practice.