Reduced overwinter survival of unharvested corn in fields with cover crops

Abstract

Volunteer corn arising from unharvested kernels in fields is a common problem that reduces yield of crops like soybean in intensive rotational agricultural systems. Over the last decade, farmers in the Midwestern United States have increased use of cover crops to improve soil health and suppress weeds in corn-soybean rotational agriculture. We assessed whether the fate of unharvested corn kernels in cover-cropped fields differed from fields without cover crops. After the 2018 harvest season, we recorded overwinter removal and spring 2019 germination of corn kernels from plots in six fields in Tippecanoe county, west-central Indiana, United States. We used mixed effects logistic regression to model the role of a cereal rye cover crop, bare ground, soil drainage class, distance from field edge, and average height of vegetation on mortality of kernels. Probability of kernel absence from a plot was greater in fields planted to cover crops (0.93-0.98) than in no-till fields without cover crops (0.53-0.85). Distance from field edge was positively related to kernel loss in cover-cropped fields, but negatively related to loss in fields without cover crops. Within cover-cropped fields, kernel removal near field edges increased to levels comparable to field interiors only for plots with >15% bare ground. Cover crops substantially reduced survival of corn kernels that serve as prospective volunteer corn, consistent with increased foraging activity and use of cover-cropped fields by vertebrate seed predators. K E Y W O R D S kernel germination, seed predators, volunteer corn, waste grain, Zea mays 1 | INTRODUCTION Volunteer corn (Zea mays L.) is a common problem in rotational agriculture and occurs when kernels are left behind after harvest and survive to grow during the following commodity-crop season. Competition from volunteer corn decreases yield by outcompeting the intended commodity crop for sunlight, water, and nutrients and can result in reduced profit because of costs associated with chemical and mechanical removal of volunteer plants (Cerdeira & Duke, 2006; Marquardt, Krupke, &