Advancing agroecosystem management through strategic cover crop selection: The role of species identity and community composition for productivity and climate change mitigation

Context: Cover cropping may improve soil fertility, nutrient cycling, and soil carbon (C) stocks, yet its effects on nitrous oxide (N2O) emissions and soil greenhouse gas balances remain unclear. The impact of cover crop species and mixtures varies over time, requiring further study. Objectives: This study aimed to assess the agronomic and environmental performance of different cover crops, including hairy vetch, rye, radish, their mixtures, and a seven-species mix, over three years. Methods: Over a three-year field experiment, we tested nine cover crop treatments - including rye, hairy vetch, radish, and their mixtures - and assessed their effects on biomass production, nitrogen (N) and carbon (C) inputs, soil macronutrients (N, P, K), greenhouse gas emissions (N2O), and yields of maize, sunflower, and soybean. Results: Hairy vetch and rye produced higher biomass, while radish contributed most to soil C inputs below-ground. Hairy vetch provided high N inputs (>200 kg N ha(-1) annually) but increased N2O emissions, revealing a trade-off between fertility and greenhouse gas emissions. Rye and radish emitted less N2O, with rye increasing soil organic C and potassium availability. The rye and vetch mixture combined high biomass production and soil C sequestration with moderate N2O emissions, making it a promising option for balancing productivity and sustainability. Rye-based treatments achieved a positive net soil CO2 balance. Sunflower and maize N uptake improved after vetch and rye-vetch cover crops, while soybean yield remained unaffected. Conclusion and implications: Cover crop mixtures with complementary traits can balance productivity and environmental impacts. Integrating rye and vetch enhances ecological functions, supporting sustainable crop production while mitigating climate change.