Abstract Climate-smart agriculture management practices such as no-tillage (NT) and cover crops (CCs) have been widely applied and are expected to offer multiple environmental benefits (e.g., soil carbon sequestration, yield stability, and climate resilience). However, the long-term effects of these management practices, especially their synergistic interaction, have not been well addressed. This study used an improved agroecosystem model (DLEM-Ag) to explore the synergistic effects of NT and CCs on soil carbon dynamics in a continuous maize system in the middle south of the United States for 1970–2099. Simulation results for 1970–2018 show that NT, relative to conventional tillage (CT), led to carbon gains (0.22 Mg C ha−1 yr−1) in the topsoil in a CC-inclusive continuing maize system; however, NT per se brought minor net carbon gains. This well captures the field observations. Model factorial analyses reveal that soil carbon sequestration was highly correlated with biomass carbon inputs from both the winter cereal CC and the summer maize. Elevated CO2 and warming effects were the main contributors to soil carbon gains, as these promote CC growth. Further model projections suggest that soil organic carbon would increase in the RCP 8.5 future scenarios (2019–2099), with greater gains under NT-CCs than under CT-CCs (0.089 vs. 0.058 Mg C ha−1 yr−1), largely due to enhanced CC biomass production. Moreover, NT-CCs would reduce carbon loss compared to CT-CCs (-0.002 vs. -0.017 Mg C ha−1 yr−1) in the RCP 2.6 scenarios. Our study highlights the importance of CCs in enhancing cropland carbon sequestration and indicates that NT and CCs, taken together, can serve as a viable strategy to ensure crop production through promoting soil health in similar maize cropping systems.

中文翻译：

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评估气候变化下长期玉米种植系统免耕和覆盖作物对土壤碳动态的协同效应

摘要 气候智能型农业管理实践，如免耕 (NT) 和覆盖作物 (CCs) 已被广泛应用，并有望提供多种环境效益（例如，土壤碳固存、产量稳定性和气候适应能力）。然而，这些管理实践的长期影响，尤其是它们的协同作用，尚未得到很好的解决。本研究使用改进的农业生态系统模型 (DLEM-Ag) 来探索 NT 和 CCs 对 1970-2099 年美国中南部连续玉米系统土壤碳动态的协同作用。1970-2018 年的模拟结果表明，相对于常规耕作 (CT)，NT 导致在包含 CC 的连续玉米系统中表土中的碳增加（0.22 Mg C ha-1 yr-1）；然而，NT 本身带来了少量的净碳收益。这口井捕获了现场观察结果。模型因子分析表明，土壤碳固存与来自冬季谷物 CC 和夏玉米的生物量碳输入高度相关。CO2 升高和变暖效应是土壤碳增加的主要贡献者，因为这些促进了 CC 的生长。进一步的模型预测表明，在 RCP 8.5 未来情景（2019-2099）中，土壤有机碳将增加，NT-CC 下的增益大于 CT-CC（0.089 对 0.058 Mg C ha−1 yr−1），主要是由于增强的 CC 生物质产量。此外，在 RCP 2.6 情景中，与 CT-CC（-0.002 对 -0.017 Mg C ha-1 yr-1）相比，NT-CC 将减少碳损失。我们的研究强调了 CCs 在增强农田碳固存方面的重要性，并表明 NT 和 CCs 结合起来，