Plumhoff, M., R. K. Connell, A. Bressler, and J. Blesh. 2022. Management history and mixture evenness affect the ecosystem services from a crimson clover-rye cover crop. Agriculture, Ecosystems & Environment 339:108155.
Cover crop mixtures of functionally distinct species may increase multiple ecosystem services, depending on their productivity and composition. We assessed how unique management legacies, and resulting soil fertility properties, influenced the functions provided by a cover crop mixture. We used the Kellogg Biological Station’s long-term Main Cropping Systems Experiment to test the legacy effects of four management systems (ranging from conventional to organic) on the production and function of crimson clover and cereal rye cover crops grown alone and in mixture, with a focus on their potential for improving agroecosystem N retention and supply. We applied bromide as a conservative tracer of solute flow in the soil profile to assess management legacy and cover crop treatment effects on potential anion leaching. A history of ecological nutrient management practices, including long-term cover crop use, increased soil fertility. Higher soil fertility, in turn, increased spring cover crop biomass and mixture evenness, and percent recovery of bromide, an estimate of soil anion retention. Mixture evenness was positively related to higher cover crop C/N ratios, N retention in corn biomass, and percent of clover N from fixation. In legacies with lower soil fertility, clover was more competitive than rye in the mixtures. Our results show that the benefits from cover crop mixtures depend on the management context into which they are adopted. In lower fertility soils with higher nutrient leaching potential, we suggest increasing crop functional diversity by including single species cover crops at different points within a crop rotation to build soil fertility. Once background soil fertility has been developed, farmers could include mixtures in their agroecosystems to maximize the functions provided by cover crops.
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