Preventing degradation of soil quality and productivity entails development of sustainable practices to enhance soil organic matter. We followed soil organic carbon (OC) accumulation during 3 years long‐field experiments in two different Italian soils under conventional tillage (TRA), reduced tillage (MIN), green manure (GM) and two rates (low, CMPL, and, high, CMPH) of mature compost amendments. Despite soil textures differences, CMP additions enhanced in both field sites OC accumulation in either bulk soils or water‐stable aggregates (WSA), especially for CMPH, that was more pronounced than for MIN and GM. While the sum of OC in WSA showed an average retention of 80–90% of cumulative carbon added with compost, incorporated OC in WSA of MIN and GM reached only 26 and 55% of total carbon amended with fresh biomass for the light and heavy textured soils, respectively. Hence, MIN and GM accumulated SOC only up to the physical saturation limit dictated by soil texture, whereas CMP retained a larger additional SOC than TRA due to hydrophobic affinity among apolar domains progressively added to soil with humified compost. Nuclear magnetic resonance spectra of humus extracted after the first and third treatment year confirmed this behaviour. While no changes were observed in spectra for MIN and GM, humic extracts from CMP showed significantly larger content of apolar alkyl and aromatic moieties after the third experimental year. Our results suggest that soil amendment with well humified compost is an effective practice to sequester carbon into agricultural soils, besides improving their organic fertility.

中文翻译：

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腐殖质改良剂有效地隔离了农业土壤中的有机碳

要防止土壤质量和生产力下降，就必须发展可持续实践以增强土壤有机质。我们在两种不同的意大利土壤中，在常规耕种（TRA），减耕（MIN），绿肥（GM）和两种速率（低，CMPL和高）下进行了3年的长期田间试验，研究了土壤有机碳（OC）的积累，CMPH）的成熟堆肥修正案。尽管土壤质地存在差异，但在大块土壤或水稳性团聚体（WSA）中，两个田间CMP的OC累积都增加了，特别是对于CMPH，这比MIN和GM更为明显。虽然WSA中的OC总和显示出堆肥添加的累积碳的平均保留量为80-90％，MIN和GM的WSA中掺入的OC分别仅占总碳的26％和55％，并用新鲜的生物质改良了轻质和重质土壤。因此，MIN和GM累积的SOC仅达到土壤质地决定的物理饱和度极限，而CMP则比TRA保留了更大的SOC，这是由于逐步添加到腐殖土中的非极性区域之间的疏水亲和力所致。在第一年和第三年治疗后提取的腐殖质的核磁共振波谱证实了这种行为。虽然没有观察到MIN和GM的光谱变化，但是从CMP提取的腐殖质在实验的第三年后显示出明显更高的非极性烷基和芳香族部分含量。