Evaluation of single and mixed cover crops species, in the Mid-South USA

Authors: Mubvumba, Partson; Tyler, Heather

Submitted to: Agronomy Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/24/2024
Publication Date: 5/6/2024
Citation: Mubvumba, P., Tyler, H.L. 2024. Evaluation of single and mixed cover crops species, in the Mid-South USA. Agronomy Journal. 116(4):1655-1669. https://doi.org/10.1002/agj2.21574.
DOI: https://doi.org/10.1002/agj2.21574

Interpretive Summary: Cover crop species informed selection is important for reducing associated costs of production without compromising benefits. The subtropical Mid-South region is lagging in cover crop adoption, partly because of the unavailability of information on common cover crop species despite being one of the major row crop-producing regions in the USA. Scientists at the USDA-ARS, Crop Production Systems Research Unit, Stoneville, MS conducted studies on commonly used cover crop species in the Mid-South region, cereal rye (CR), hairy vetch (HV), and crimson clover (CC), and their possible 2- and 3-combination mixes to assess their performance and impact on corn yields. HV had the highest yields compared to all other cover crops and similar to traditional no-cover crop practices. HV+CR, HV+CC+CR, HV, and CC increased soil health the most compared to other cover crops. HV and CC increased potassium in the subsurface depths. CC and HV lowered surface soil pH, whilst CR increased subsurface soil pH. These findings indicate that alternating CC with HV may be the best option in the short term, rotated with CR in the long run for optimum benefits in this region under corn production.

Technical Abstract: Cover crop species informed selection is critical for optimizing benefits considering associated costs of adoption and potential initial negative impact on yields despite proven benefits for sustainable production. The subtropical Midsouth region is lagging in cover crop adoption, partly due to a paucity of information in that regard despite being one of the major row crop-producing regions in the USA. Commonly used cover crop species in the region, cereal rye (CR) (Secale cereale), hairy vetch (HV) (Vicia villosa), and crimson clover (CC) (Trifolium incarnatum), and their possible 2- and 3-combination mixes were evaluated for their impact on biomass production, enzyme activities, nutrient cycling and corn (Zea mays) yields. HV+CC+CR and HV+CR produced the highest biomass compared to all species with CR being the highest amongst single species. A similar trend was observed for total nitrogen, phosphorus, and soil organic carbon, but conversely, CR had the lowest recorded corn yields. The biomass tied up nutrients and made them unavailable for corn. The no cover crop (NCC) control and HV had the highest recorded yields. HV+CR increased phosphatase, NAGase, ß-glucosidase, cellobiohydrolase enzyme activities, and FDA hydrolysis peaking by up to 45%, 74%, 62%, 68%, and 25% respectively in the surface depth in comparison to NCC. Similarly, CC was 47%, 69%, 55%, 49%, and 20% respectively. HV+CC+CR and HV were comparable to HV+CR and CR. CR was the lowest. HV and CC increased potassium in the subsurface depths. HV and CR increased calcium. All species extracted Zinc from the soil. HV, CR, and HV+CC reduced magnesium concentrations. CC and HV lowered surface soil pH, whilst CR increased subsurface soil pH, however, mixes HV+CC, HV+CR, and HV+CC+CR decreased surface soil pH. CC may be the best option in the short term, rotated with CR in the long run for optimum benefits in this region under corn production.