ABSTRACT

Conventional agriculture in the Midwest US lacks diversity, relies heavily on external inputs to maintain crop yields, and contributes to soil and water quality degradation. Using diverse crop rotations and incorporating livestock are promising solutions to these and other problems linked to current cropping systems dominated by maize (Zea mays L.) and soybean (Glycine max (L.) Merr.). To better understand how agricultural diversification comprehensively affects soil health and function, we compared 20 soil health parameters linked to critical soil ecosystem services in 1) a conventional 2-year maize-soybean rotation, and 2) a diverse 4-year maize-soybean-oat (Avena sativa L.)+alfalfa (Medicago sativa L.)-alfalfa rotation that periodically received cattle manure. The strongest and most salient improvements in soil health from the diversified, 4-year cropping system included: 8% reduction in soil resistance to root growth (p = .006), 16% increase in cation exchange capacity (p = .001), 157% increase in salt-extractable soil carbon (p = .024), and 62% increase in soil microbial biomass (p = .017). These comprehensive improvements in general soil functioning coincided with enhanced crop yields, reduced requirement for agricultural inputs, and decreased environmental impacts – all while maintaining profitability. Despite declines in cropping system diversity globally, but especially in the Midwest US, these results provide strong evidence for the benefits of diversification.

摘要

美国中西部的传统农业缺乏多样性，严重依赖外部投入来维持作物产量，并导致土壤和水质退化。使用多样化的轮作和结合牲畜是解决这些问题以及与当前以玉米 ( Zea mays L.) 和大豆 ( Glycine max (L.) Merr.) 为主的种植系统相关的其他问题的有希望的解决方案。为了更好地了解农业多样化如何全面影响土壤健康和功能，我们比较了 20 个与关键土壤生态系统服务相关的土壤健康参数：1）传统的 2 年玉米-大豆轮作，2）多样化的 4 年玉米-大豆-燕麦（Avena sativa L.）+紫花苜蓿（Medicago sativaL.)-苜蓿轮作，定期接受牛粪。多样化的 4 年种植系统对土壤健康的最强和最显着改善包括：土壤对根系生长的抵抗力降低 8% ( p = .006)，阳离子交换能力增加 16% ( p = .001)，可盐分土壤碳增加 157% ( p = .024)，土壤微生物生物量增加 62% ( p= .017)。这些对一般土壤功能的全面改善与提高作物产量、减少对农业投入的需求和减少环境影响相吻合——同时保持盈利能力。尽管全球种植系统多样性下降，尤其是在美国中西部地区，但这些结果为多样化的好处提供了强有力的证据。