Moving agricultural production systems toward a greater level of soil health is needed for sustainability. Conservation agricultural systems utilizing no or minimum tillage are an important step forward, but enhancing carbon (C) inputs with diverse cover crops and facilitating biologically active nitrogen (N) cycling are also needed. Summer cash-crop systems, particularly in the warm-humid region of the southeastern United States, may benefit from multispecies winter cover cropping if sufficient biomass were produced. We implemented a research and demonstration project utilizing multispecies cover cropping in 15 counties of North Carolina during 2015 to 2019 to assess biomass production and its effect on surface-soil properties. Winter cover crop biomass production was variable among locations, but exceeded 3,790 kg ha–1 in one-third of trials. Nitrogen contained in aboveground cover crop biomass exceeded 60 kg ha–1 in the upper third of trials. Of 30 soil properties measured in each site-year ( n = 31) at depths of 0 to 5 and 5 to 15 cm, soil-test biological activity, C mineralization during 24 days, total soil N, and Mehlich-III phosphorus (P) and potassium (K) were most consistently affected when comparing multispecies cover cropping with either no or single-species cover cropping. Despite relatively short duration of evaluations (i.e., mostly one to two years), we were able to elucidate that winter multispecies cover cropping has potential to improve soil health conditions in the region. Soil-test biological activity demonstrated the living nature of soil and was sensitive to conservation agricultural management. The support of a hands-on farmer and adviser network encouraged success.

中文翻译：

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北卡罗来纳州的免耕种植系统中的多物种覆盖种植促进土壤健康

为了实现可持续发展，需要将农业生产系统移向更高的土壤健康水平。不使用或最少耕种的保护性农业系统是向前迈出的重要一步，但是还需要通过多种覆盖作物来增加碳（C）的投入，并促进生物活性氮（N）的循环。如果生产足够的生物量，夏季经济作物系统，特别是在美国东南部温暖湿润的地区，可能会受益于多品种的冬季覆盖作物。我们于2015年至2019年在北卡罗来纳州的15个县实施了一项利用多物种覆盖作物进行种植的研究和示范项目，以评估生物量的生产及其对地表土壤特性的影响。冬季覆盖作物生物量的产量因地区而异，但在三分之一的试验中超过了3,790 kg ha-1。在试验的前三分之一中，地表覆盖作物生物量中所含的氮超过60 kg ha-1。在每个站点年度（n = 31）的0至5和5至15 cm深度中测量的30种土壤性质，土壤测试生物活性，24天的C矿化，总土壤N和Mehlich-III磷（P比较多物种覆盖种植与无或单一物种覆盖种植时，钾和钾（K）受到的影响最大。尽管评估时间相对较短（即大多为一到两年），但我们能够阐明冬季多物种覆盖作物的种植有潜力改善该地区的土壤健康状况。土壤测试的生物活性证明了土壤的生存特性，并且对保护性农业经营很敏感。