Studying the impact of different tillage systems on soil organic matter (SOM) dynamics is essential to define better strategies to improve soil fertility and soil organic carbon (SOC) sequestration. We used density fractionation to assess the changes in SOM in an Inceptisol following nine-years of contrasting tillage under wheat (Triticum aestivum) based cropping systems. The major objective of the study was to investigate the amount of C content within soil aggregates as influenced by tillage and residue management. For this a nine-year old experiment was conducted with two tillage practices in main plots (zero-tillage: ZT and conventional tillage: CT) and four residue management practices in sub-plots (No residue: NR, wheat residue: WR, soybean residue: SR and wheat + soybean residue: WR + SR). The results indicated that SOC content increased by ∼48, 42 and 36%, respectively, in WR + SR, SR and WR plots compared with the NR plots in the 0-5 cm soil layer. The SOC content within macroaggregates were ∼30 and 25% higher in the ZT plots than CT in the 0-5 and 5-15 cm soil depths, respectively. The intra-aggregate particulate organic matter (iPOM) inside microaggregates within macroaggregates (iPOM_mM) was ∼16% higher in the CT than the ZT plots. Tillage management had no significant effect on light fraction inside microaggregates within macroaggregates (LF_mM) and iPOM_mM SOC contents inside microaggregates within macroaggregates (mM) in the surface soil, but residue management improved LF_mM and iPOM_mM SOC contents. The WR + SR, SR and WR plots had ∼73, 40 and 35% more LF_mM SOC content, respectively, than NR plots. Within free microaggregates in the surface soil, the LF_m SOC content was significantly enhanced due to ZT operation by ∼61% than the CT plots but not by crop residue addition. The iPOM_mM and iPOM_m fraction accounted for about ∼35 and 51% of the total SOC content within macroaggregates and microaggregates, respectively. That indicates the role of iPOM fraction in SOC sequestration within the soil aggregates in tropical Inceptisol. Plots under ZT had ∼38% more C content inside microaggregates within macroaggregates (mM) than CT (2.31 Mg ha^-1), indicating ZT management could be adopted for C stabilization within aggregates.

研究不同耕作制度对土壤有机质（SOM）动力学的影响对于定义改善土壤肥力和土壤有机碳（SOC）隔离的更好策略至关重要。我们使用密度分级法评估了在小麦（小麦）下九年对比耕作后，Inceptisol中SOM的变化。）的种植系统。该研究的主要目的是调查耕作和残留物管理对土壤团聚体中碳含量的影响。为此，我们进行了一个长达9年的实验，在主要地块进行了两种耕作实践（零耕作：ZT，常规耕作：CT），在子样地进行了四种残留管理实践（无残留：NR，小麦残留：WR，大豆）残留物：SR和小麦+大豆残留物：WR + SR）。结果表明，与0-5 cm土层的NR图相比，WR + SR，SR和WR图中的SOC含量分别增加了约48％，42％和36％。在ZT图中，在0-5和5-15 cm的土壤深度中，大型骨料中的SOC含量分别比CT高30到25％。大型团聚体（iPOM_mM）中的微团聚体内部的团聚体内部颗粒有机物（iPOM）比ZT图高约16％。耕作管理对表层土壤中大型集料（LF_mM）和iPOM_mM SOC内的微团聚体中的轻组分和iPOM_mM SOC含量没有显着影响，但残留物管理改善了LF_mM和iPOM_mM SOC含量。WR + SR，SR和WR图分别比NR图多出约73、40和35％的LF_mM SOC含量。在表层土壤中的游离微骨料中，由于ZT操作，LF_m SOC含量比CT曲线显着提高了约61％，但没有因添加农作物残渣而增加。iPOM_mM和iPOM_m部分分别占宏观聚集体和微小聚集体中SOC的约35％和51％。这表明iPOM分数在热带Inceptisol的土壤团聚体中SOC隔离中的作用。ZT下的样区中，大型聚集体（mM）中的微聚集体内的C含量比CT（2.31 Mg ha^-1），表示可以将ZT管理用于聚合内的C稳定化。