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 belowground. 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.