College of Agronomy and Biotechnology, China Agricultural University, Key Laboratory of Farming System, Ministry of Agriculture and Rural Affairs of the People's Republic of China, Beijing, China.
CFAES Rattan Lal Center for Carbon Management and Sequestration, School of Environment and Natural Resources, The Ohio State University, Columbus, Ohio, USA.
Glob Chang Biol. 2022 Feb;28(3):693-710. doi: 10.1111/gcb.15968. Epub 2021 Nov 14.
Mechanisms of soil organic carbon (SOC) stabilization have been widely studied due to their relevance in the global carbon cycle. No-till (NT) has been frequently adopted to sequester SOC; however, limited information is available regarding whether sequestered SOC will be stabilized for long term. Thus, we reviewed the mechanisms affecting SOC stability in NT systems, including the priming effects (PE), molecular structure of SOC, aggregate protection, association with soil minerals, microbial properties, and environmental effects. Although a more steady-state molecular structure of SOC is observed in NT compared with conventional tillage (CT), SOC stability may depend more on physical and chemical protection. On average, NT improves macro-aggregation by 32.7%, and lowers SOC mineralization in macro-aggregates compared with CT. Chemical protection is also important due to the direct adsorption of organic molecules and the enhancement of aggregation by soil minerals. Higher microbial activity in NT could also produce binding agents to promote aggregation and the formation of metal-oxidant organic complexes. Thus, microbial residues could be stabilized in soils over the long term through their attachment to mineral surfaces and entrapment of aggregates under NT. On average, NT reduces SOC mineralization by 18.8% and PE intensities after fresh carbon inputs by 21.0% compared with CT (p < .05). Although higher temperature sensitivity (Q ) is observed in NT due to greater Q in macro-aggregates, an increase of soil moisture regime in NT could potentially constrain the improvement of Q . This review improves process-based understanding of the physical and chemical mechanism of protection that can act, independently or interactively, to enhance SOC preservation. It is concluded that SOC sequestered in NT systems is likely to be stabilized over the long term.
由于在全球碳循环中的重要性，土壤有机碳（SOC）稳定的机制已得到广泛研究。免耕（NT）已被频繁采用以固定 SOC；然而，关于固定的 SOC 是否会长期稳定，信息有限。因此，我们综述了影响 NT 系统中 SOC 稳定性的机制，包括激发效应（PE）、SOC 的分子结构、团聚体保护、与土壤矿物质的结合、微生物特性和环境影响。尽管 NT 中 SOC 的分子结构更稳定，但 SOC 的稳定性可能更依赖于物理和化学保护。平均而言，NT 比传统耕作（CT）增加了 32.7%的大团聚体，并且降低了大团聚体中的 SOC 矿化。由于有机分子的直接吸附和土壤矿物质对团聚体的增强，化学保护也很重要。NT 中较高的微生物活性也可以产生结合剂，促进团聚体的形成和金属氧化剂有机复合物的形成。因此，微生物残留物可以通过附着在矿物表面和 NT 下的团聚体的捕获而在土壤中长期稳定。平均而言，与 CT 相比，NT 减少了 SOC 矿化 18.8%，减少了新鲜碳输入后的 PE 强度 21.0%（p < 0.05）。尽管 NT 中由于大团聚体中较大的 Q 导致更高的温度敏感性（Q ），但 NT 中土壤水分状况的增加可能会限制 Q 的提高。本综述提高了对物理和化学保护机制的基于过程的理解，这些机制可以独立或相互作用，增强 SOC 的保存。结论是，NT 系统中固定的 SOC 很可能长期稳定。
