Assessing Cover Crop Impacts on Corn and Soybean Yields at the Field-Scale Using UAVs.

Cover crops are promoted as a key strategy for reducing nitrate losses while improving soil quality in the US Midwest. However, adoption of cover crops remains low in this region, in part due to perceived negative impacts on yield. Although cover crop biomass and N uptake at termination is variable across a field which has implications for subsequent crop growth, there is little information evaluating the spatial variability of cover crop performance and linking this with yield outcomes at the field-scale. The objective of this study was to layer several sets of UAV imagery obtained at cover crop termination and during early-season corn (Zea mays L.) and soybean [Glycine Max (L.) Merr.] growth to assess spatial relationships and subsequent positive/negative impacts on yield within cover crop strips as compared to non-cover crop strips in four Soil Health Partnership field trials in Illinois. Two sites had triticale as a cover crop before corn and two sites had cereal rye before soybean. We utilized a high-resolution method for mapping aboveground biomass in cover and cash crops using an unmanned aerial vehicle (UAV) mounted with a multispectral camera. For corn, we hypothesized that increased cover crop biomass and N uptake would be associated with lower early-season corn biomass and higher N deficiencies (as indicated by NDVI), ultimately leading to reduced yield. For soybean, we hypothesized that increased cover crop biomass and N uptake would have minimal impacts on early season growth and final yield.