Straw returning has been broadly recognized as an agronomic strategy to manage soil quality and has great potential to enhance soil fertility. However, soil microbial metabolism and ecosystem multifunctionality in response to various straw returning strategies in the black soil remain poorly understood. Here, a 5-year field trial was conducted to discover the effects of four straw management strategies (SIDP, straw incorporation by deep ploughing; SIRT, straw incorporation by rotary tillage; SM, straw mulching with no-tillage; SR, straw removal with no-tillage) on the soil biochemical properties in the topsoil (0–20 cm) and subsoil (20–40 cm). SM maintained soil fertility, as evidenced by increases in soil organic carbon, total nitrogen, dissolved organic carbon, and nitrogen, compared with SIDP and SR. Additionally, this strategy promoted microbial biomass. It also stimulated nutrient cycling through increased enzyme activity. Meanwhile, SM alleviated microbial carbon limitation and promoted the shift of soil microbial metabolism from P limitation to N limitation compared to other treatments, especially in the subsoil. This shift was directly influenced by soil available nutrients and microbial properties, as revealed by the partial least-squares path modeling analysis. Besides, SM promoted soil ecosystem multifunctionality by 29%–37% in both soil layers compared to SIDP and SR. Random forest analysis indicated that soil microbial biomass and activity were the main drivers of this increase in multifunctionality. In conclusion, straw returning with no-tillage is an optimal straw management strategy for improving the soil biochemical properties, stimulating enzyme activities, alleviating microbial carbon limitation, and increasing ecosystem multifunctionality in the Northeast Plain.

中文翻译：

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免耕秸秆还田缓解了微生物代谢碳的限制，改善了东北平原土壤的多功能性


秸秆还田已被广泛认为是管理土壤质量的一种农艺策略，在提高土壤肥力方面具有巨大潜力。然而，对黑土中各种秸秆返回策略的土壤微生物代谢和生态系统多功能性仍然知之甚少。在这里，进行了一项为期 5 年的田间试验，以发现四种秸秆管理策略（SIDP，通过深耕秸秆掺入;SIRT，通过旋耕秸秆并入;SM，免耕秸秆覆盖;SR，免耕去除秸秆）对表土 （0-20 cm） 和底土 （20-40 cm） 土壤生化特性的影响。与 SIDP 和 SR 相比，土壤有机碳、总氮、溶解有机碳和氮的增加证明了这一点。此外，这种策略促进了微生物生物量。它还通过增加酶活性来刺激营养循环。同时，与其他处理相比，SM 缓解了微生物碳限制，促进了土壤微生物代谢从 P 限制向 N 限制转变，尤其是在底土中。正如偏最小二乘路径建模分析所揭示的那样，这种转变直接受到土壤可用养分和微生物特性的影响。此外，与 SIDP 和 SR 相比，SM 在两个土壤层中都促进了 29%–37% 的土壤生态系统多功能性。随机森林分析表明，土壤微生物生物量和活性是多功能性增加的主要驱动力。 综上所述，免耕秸秆还田是东北平原改善土壤生化性质、刺激酶活性、缓解微生物碳限制和增加生态系统多功能性的最佳秸秆管理策略。