Use of soil cover crops of different families in crop rotation or succession under no-tillage system (NTS) for onion production results in higher soil quality compared to land use systems with less plant diversity. The objective was to evaluate the effect of using different combinations of plant species from different botanical families in rotation and succession of soil cover crops in NTS for onion production on formation of macroaggregates, mesoaggregates, and microaggregates, and on total organic C (TOC) and N (TN) contents, including isotopic forms of C and N, in soil aggregates and bulk soil. The treatments (T) evaluated were maize/onion (NTS-T1); cover plants (winter)/onion (NTS-T2); maize/winter grasses/onion (NTS-T3); velvet bean/onion (NTS-T4); millet/cover plants (winter)/onion (NTS-T5); velvet bean/rye/onion (NTS-T6); maize/onion in conventional tillage system (CTS-T7); and intercrop cover plants (summer)/onion (NTS-T8). We evaluated macroaggregates (8.0–0.25 mm), microaggregates (<0.25 mm), and bulk soil (<2.0 mm) at depths of 0–5, 5–10, and 10–20 cm, in a nine-year field experiment. The greater plant diversity in T2–T6 and T8 resulted in higher geometric mean diameter (GMD) of aggregates compared to T1 and T7. The T8 was more efficient in increasing GMD in the 10–20 cm soil depth than the other treatments. The T1 was more efficient in improving the evaluated soil physical and chemical attributes than T7. The use of NTS with plants of the Poaceae and Fabaceae families in single or intercrop systems for onion production resulted in higher TOC and TN contents in the 0–5 and 5–10 cm soil depths compared to CTS. Isotope 15N measurements showed that C and N were more protected in microaggregates in all evaluated treatments and depths compared to macroaggregates and bulk soil. Macroaggregates had more TOC and TN than microaggregates.

中文翻译：

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在作物演替和轮作下用洋葱种植的土壤团聚体和大块土壤中 13C 和 15N 的聚集指数、碳、氮和自然丰度

与植物多样性较少的土地利用系统相比，在免耕系统 (NTS) 下在作物轮作或轮作中使用不同科的土壤覆盖作物进行洋葱生产会导致更高的土壤质量。目的是评估在 NTS 中使用来自不同植物科的植物物种的不同组合轮作和连续土壤覆盖作物生产洋葱对大团聚体、中间团聚体和微团聚体形成的影响，以及对总有机碳 (TOC) 和土壤团聚体和大块土壤中的 N (TN) 含量，包括 C 和 N 的同位素形式。评价的处理（T）是玉米/洋葱（NTS-T1）；覆盖植物（冬季）/洋葱（NTS-T2）；玉米/冬草/洋葱（NTS-T3）；天鹅绒豆/洋葱（NTS-T4）；小米/覆盖植物（冬季）/洋葱（NTS-T5）；天鹅绒豆/黑麦/洋葱（NTS-T6）；传统耕作系统中的玉米/洋葱 (CTS-T7)；和间作覆盖植物（夏季）/洋葱 (NTS-T8)。我们在为期 9 年的田间试验中评估了 0-5、5-10 和 10-20 厘米深度的大团聚体（8.0-0.25 毫米）、微团聚体（<0.25 毫米）和大块土壤（<2.0 毫米）。与 T1 和 T7 相比，T2-T6 和 T8 中更大的植物多样性导致聚集体的几何平均直径 (GMD) 更高。T8 在增加 10-20 cm 土壤深度的 GMD 方面比其他处理更有效。T1比T7更能有效地改善评价的土壤理化属性。与 CTS 相比，将 NTS 与禾本科和豆科植物在单一或间作系统中用于洋葱生产导致 0-5 和 5-10 厘米土壤深度中的 TOC 和 TN 含量更高。同位素 15N 测量表明，与大团聚体和大块土壤相比，在所有评估的处理和深度中，微团聚体中的 C 和 N 受到更多保护。大团聚体比​​微团聚体具有更多的 TOC 和 TN。