Crop residue burning or removal from fields has detrimental impacts on crop productivity and soil quality due to decreased carbon (C) sustainability under intensive rice–wheat system (RWS). The conservation agriculture (CA) based on reduced tillage coupled with crop residue retention and raising leguminous green manure (GM) (Sesbania aculeata) during the intervening period between wheat harvest and rice establishment offers opportunities for the restoration of C sustainability. We studied the impacts of tillage intensity, crop residue management, and GM on soil organic C dynamics within the macro- and micro-aggregates after 6 years of RWS. Four main plot treatments in rice including combinations of wheat straw and GM were conventional till puddled transplanted rice with no wheat straw (CTR_W0), CTR with 25% wheat stubbles retained (CTR_W25), CTR_W0 plus GM (CTR_W0 + GM), and CTR_W25 plus GM (CTR_W25 + GM). Three sub-plot treatments in subsequent wheat were CT with rice straw removed (CTW_R0), zero tillage with rice straw removed (ZTW_R0), and the ZT with 100% rice straw retained as surface mulch (ZTW_R100). The ZTW_R100 significantly (p < 0.05) increased the soil moisture retention at field capacity (FC) (Ψm = 0.33bar) and available moisture content (AWC) (Ψm = 0.33–15 bar), compared with CTW_R0. The ZTW_R100 treatment also significantly increased the dehydrogenase (DHA), cellulase, and β-glucosidase activities by ~54, 56, and 45% and the easily extractable glomalin (EEG)- and total glomalin (TG)-related soil protein concentration by ~30.5 and 9.4%, respectively, compared with the CTW_R0 treatment. The four C fractions of variable oxidizability increased significantly within both soil macro- and micro-aggregates under CTR_W25 + GM and ZTW_R100 over their respective control treatments (CTR_W0 and CTW_R0). Crop residue retention plus GM significantly improved the proportion of total water-stable aggregates (WSA), mean weight diameter (MWD), and aggregate ratio (AR), compared with the treatments involving residue removal and no GM. The principal component analysis (PCA) elucidated FC, TG in macro-aggregates, non-labile C in micro- and macro-aggregates, WSA, and the permanent wilting point (PWP) as the most dominant indicators for assessing soil quality under CA based sustainable practices in RWS.

由于集约化稻麦系统 (RWS) 下碳 (C) 可持续性降低，农作物残茬燃烧或从田间清除会对作物生产力和土壤质量产生不利影响。在小麦收获和水稻种植之间的中间时期，基于减少耕作、作物残留物保留和提高豆科绿肥 (GM) ( Sesbania aculeata ) 的保护性农业 (CA) 为恢复 C 可持续性提供了机会。我们研究了 RWS 6 年后，耕作强度、作物残茬管理和 GM 对宏观和微观聚集体土壤有机碳动态的影响。水稻的四种主要地块处理，包括小麦秸秆和转基因的组合，是常规的直到没有小麦秸秆的水坑移栽水稻（CTR _W0)、保留 25% 小麦残茬的 CTR (CTR _W25 )、CTR _W0加 GM (CTR _W0 + GM) 和 CTR _W25加 GM (CTR _W25 + GM)。随后小麦的三个子小区处理是去除稻草的CT（CTW _R0）、去除稻草的零耕（ZTW _R0）和保留100%稻草作为表面覆盖物的ZT（ZTW _R100）。_{与 CTW R0}相比， ZTW _R100显着（p < 0.05）增加了土壤持水量（FC）（Ψm = 0.33bar）和有效水分含量（AWC）（Ψm = 0.33-15 bar）。ZTW _R100处理还显着增加了脱氢酶 (DHA)、纤维素酶和 β-葡萄糖苷酶活性约 54%、56% 和 45%，易于提取的球蛋白 (EEG) 和总球蛋白 (TG) 相关的土壤蛋白浓度增加约 30.5 和与 CTW _R0处理相比，分别为 9.4% 。在 CTR _W25 + GM 和 ZTW _R100下，与各自的对照处理（CTR _W0和 CTW _R0）。与去除残留物和不使用转基因的处理相比，作物残茬保留加转基因显着提高了总水稳性团聚体的比例 (WSA)、平均重量直径 (MWD) 和团聚比 (AR)。主成分分析 (PCA) 阐明了大团聚体中的 FC、TG、微观和宏观团聚体中的非不稳定 C、WSA 和永久萎蔫点 (PWP) 作为基于 CA 的土壤质量评估的最主要指标RWS 的可持续实践。