Cover cropping is an effective management practice for reducing nitrogen (N) losses to the environment from agriculture fields in the Upper Mississippi River Basin (UMRB). Cereal rye (CR; Secale cereale L.) and hairy vetch (HV; Vicia villosa Roth) are two of the most common cover crop species grown in the UMRB. Few studies have examined the effect of corn (Zea mays L.) or soybean (Glycine max L.) management on the rate and timing of N and carbon (C) release from CR and HV residue. The objective of this study was to measure the effect of cash crop rotation (continuous corn, corn–soybean, and soybean–corn), cover crop selection (CR, HV, and a CR/HV mixture), and tillage (spring disk or transitional no-till) on the rate and timing of N and C loss from litterbags as an estimate of N and C release from cover crop residue. Our results demonstrated that rotation did not impact cover crop N and C release. However, HV released both N and C at rates 2.1 and 1.6 times faster, respectively, than treatments that included CR. Furthermore, where residue was incorporated, rates of N and C release were 2.7 and 3.0 times faster, respectively, than where residue was not incorporated. When averaged across cover crop species and tillage, 17% to 56% of nutrient release occurred, after planting, during vegetative cash crop growth stages. Results from this study advanced the understanding of how cropping systems management can influence release of N and C from cover crop residue.

中文翻译：

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覆盖作物残留物的碳和氮释放及其对种植系统管理的影响

覆盖种植是减少上密西西比河流域 (UMRB) 农田对环境造成的氮 (N) 损失的有效管理实践。谷物黑麦（CR；Secale creame L.）和多毛紫云英（HV；Vicia villosa Roth）是 UMRB 中最常见的两种覆盖作物物种。很少有研究考察玉米 (Zea mays L.) 或大豆 (Glycine max L.) 管理对 CR 和 HV 残留物中氮和碳 (C) 释放的速率和时间的影响。本研究的目的是测量经济作物轮作（连续玉米、玉米-大豆和大豆-玉米）、覆盖作物选择（CR、HV 和 CR/HV 混合物）和耕作（春盘或过渡免耕）关于垃圾袋中 N 和 C 损失的速率和时间，作为对覆盖作物残留物中 N 和 C 释放的估计。我们的结果表明轮作不会影响覆盖作物 N 和 C 的释放。然而，HV 释放 N 和 C 的速率分别比包括 CR 的处理快 2.1 和 1.6 倍。此外，在掺入残留物的情况下，氮和碳的释放速率分别比未掺入残留物的地方快 2.7 和 3.0 倍。当覆盖作物种类和耕作方式平均时，17% 到 56% 的养分释放发生在种植后的营养经济作物生长阶段。这项研究的结果促进了对种植系统管理如何影响覆盖作物残留物中氮和碳释放的理解。在加入残留物的情况下，N 和 C 的释放速率分别比未加入残留物的情况快 2.7 和 3.0 倍。当覆盖作物种类和耕作方式平均时，17% 到 56% 的养分释放发生在种植后的营养经济作物生长阶段。这项研究的结果促进了对种植系统管理如何影响覆盖作物残留物中氮和碳释放的理解。在加入残留物的情况下，N 和 C 的释放速率分别比未加入残留物的情况快 2.7 和 3.0 倍。当覆盖作物种类和耕作方式平均时，17% 到 56% 的养分释放发生在种植后的营养经济作物生长阶段。这项研究的结果促进了对种植系统管理如何影响覆盖作物残留物中氮和碳释放的理解。