Increasing crop diversity has been highly recommended because of its environmental and economic benefits. However, the impacts of crop diversity on soil properties are not well documented. Thus, the present study was conducted to assess the impacts of crop diversity on selected soil quality indicators. The cropping systems investigated here included wheat (Triticum aestivum L.) grown continuously for 5 years as mono-cropping (MC), and a 5-year cropping sequence [(wheat–cover crop (CC)–corn (Zea mays L.)–pea (Pisum sativum L.) and barley (Hordeum vulgare L.)–sunflower (Helianthus annuus L.)]. Each crop was present every year. This study was conducted in the northern Great Plains of North America, and soil quality data were collected for 2016 and 2017. Selected soil quality indicators that include: soil pH, organic carbon (SOC), cold water-extractable C (CWC) and N (CWN), hot water-extractable C (HWC) and N (HWN), microbial biomass carbon (MBC), bulk density (BD), water retention (SWR), wet soil aggregate stability (WAS), and urease and β-glucoside enzyme activity were measured after the completion of 5-year rotation cycle and the following year. Crop diversity did not affect soil pH, CWC, CWN, HWC, HWN and SWR. Cropping systems that contained CC increased SOC at shallow depths compared to the systems that did not have CC. Crop diversity increased WAS, MBC, and urease and β-glucoside enzyme activity compared with the MC. Comparison of electrical conductivity (EC) measured in this study to the baseline values at the research site prior to the establishment of treatments revealed that crop rotation decreased EC over time. Results indicate that crop diversity can improve soil quality, thus promoting sustainable agriculture.

中文翻译：

---

受 5 年多样化和单一种植系统影响的土壤质量指标

由于其环境和经济效益，强烈建议增加作物多样性。然而，作物多样性对土壤特性的影响并没有得到很好的记录。因此，本研究旨在评估作物多样性对选定土壤质量指标的影响。这里研究的种植系统包括小麦（小麦L.) 作为单一作物 (MC) 连续种植 5 年，以及 5 年种植序列 [(小麦-覆盖作物 (CC)-玉米 (玉米L.)–豌豆 (豌豆L.) 和大麦 (大麦L.)–向日葵 (向日葵.)]。每种作物每年都有。本研究在北美大平原北部进行，收集了 2016 年和 2017 年的土壤质量数据。选定的土壤质量指标包括：土壤 pH 值、有机碳 (SOC)、冷水可萃取 C (CWC) 和 N (CWN)、热水可提取 C (HWC) 和 N (HWN)、微生物生物量碳 (MBC)、容重 (BD)、保水性 (SWR)、湿土团聚体稳定性 (WAS) 和脲酶和β-葡萄糖苷酶活性在5年轮换周期完成后和次年测量。作物多样性不影响土壤 pH、CWC、CWN、HWC、HWN 和 SWR。与不含 CC 的系统相比，包含 CC 的种植系统在浅层深度增加了 SOC。作物多样性增加了 WAS、MBC 和脲酶和β-葡萄糖苷酶活性与MC相比。将本研究中测量的电导率 (EC) 与建立处理之前研究地点的基线值进行比较表明，随着时间的推移，作物轮作降低了 EC。结果表明，作物多样性可以改善土壤质量，从而促进可持续农业。