Soils provide important ecosystem services necessary for sustainable agriculture. The ability of soils to provide nutrients to plants, recycle plant residues, and store nutrients, contributes to plant productivity, organic matter (OM) formation, and the prevention of nutrient leaching and runoff. These ecosystem services are largely driven by microbially mediated soil processes. Plant diversity has been shown to positively influence microbially mediated soil functions, including nutrient provisioning and carbon cycling. Gaps remain in understanding how plant diversity affects these ecosystem services. Specifically, the role of functional diversity in promoting microbially mediated nutrient provisioning and carbon cycling in soils.I investigated the effects of four cover crop species, two grasses and two legumes, on the ecosystem services of nutrient provisioning and carbon cycling. These cover crops were planted individually, as a mixture of one grass and one legume, and as a mixture of all four species. I found positive effects of cover crops on nutrient provisioning and carbon cycling ecosystem services. One mixture of a grass and a legume outperformed its constituent monocultures, while another mixture did not, indicating the important of both functional diversity and species level interactions. Cover crop performance was not always correlated to plant biomass, indicating the importance of diversity and species level effects. The four crop crop mixture was consistently outperformed by the two species mixtures of a grass and a legume, indicating the importance of functional diversity rather than simple species diversity. This research demonstrates the positive effects of functional diversity on microbially mediated nutrient provisioning services and carbon cycling. However the inconsistent effects between cover crop species and cover crop mixtures also indicates a need for further research on plant functional traits, plant species level interactions, and plant diversity effects on microbially mediated soil functions.
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