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.

功能不同物种的覆盖作物混合物可能会增加多种生态系统服务，具体取决于它们的生产力和组成。我们评估了独特的管理遗产和由此产生的土壤肥力特性如何影响覆盖作物混合物提供的功能。我们使用凯洛格生物站的长期主要种植系统实验来测试四种管理系统（从传统到有机）对单独和混合种植的深红色三叶草和谷物黑麦覆盖作物的生产和功能的遗留影响，关注它们在改善农业生态系统氮保留和供应方面的潜力。我们应用溴化物作为土壤剖面中溶质流动的保守示踪剂，以评估管理遗留问题和覆盖作物处理对潜在阴离子浸出的影响。生态养分管理实践的历史，包括长期覆盖作物的使用，增加土壤肥力。反过来，较高的土壤肥力会增加春季覆盖作物的生物量和混合均匀度，以及溴化物的回收率，这是对土壤阴离子保留的估计。混合均匀度与较高的覆盖作物 C/N 比、玉米生物量中的 N 保留以及来自固定的三叶草 N 百分比呈正相关。在土壤肥力较低的遗产中，三叶草在混合物中比黑麦更具竞争力。我们的研究结果表明，覆盖作物混合物的好处取决于采用它们的管理环境。在具有较高养分浸出潜力的肥力较低的土壤中，我们建议通过在轮作中的不同点包括单一物种覆盖作物来提高土壤肥力，从而增加作物功能多样性。