The stability and chemical composition of SOM are related to the changes of the proportions of old and young SOM. However, there are few studies that investigated the effects of no-tillage (NT) on the stability, chemical composition, and sources of SOM. In this study, the effects of 9-years of NT on the contents of total, thermally labile and stable SOM, their chemical composition and the contributions from C and C plants were determined. Before application of NT, the field has been used for C maize cultivation under conventional tillage (CT) management about 80 years after initial C grassland reclamation. Soil samples were collected in the 0–20 cm soil profile. Under NT treatment, the contents of total SOC, thermally labile and stable SOC, and C-SOC decreased with soil depths. However, they were greater in the 0–10 cm layers than that in the 10–20 cm layer under CT. The contents of C-SOC showed no change with depths under both of tillage treatments. NT had greater contents of total SOC, C-SOC, thermal-labile SOC, and C-SOC than CT in the 0–5 cm layer, but lower in the subsoil layers. The contents of C-SOC decreased in the 0–5 cm layer under NT. The alkyl-C and O-alkyl-C were the main fractions of thermal-labile SOM and aromatic-C was the dominant fraction of thermal-stable SOM. C-SOC (young SOC) was significantly positively correlated with alkyl-C and O-alkyl-C and negatively correlated with aromatic-C. Our results indicated that: (1) compared with continuously CT, applying NT resulted in SOC accumulation in the surface layer, (2) more maize residue input increased the new thermally labile and stable SOM yet lead to decrease the C-SOC under NT, (3) the contributions of C and C-direved SOM determined the chemical compositions of various SOM pools.

中文翻译：

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免耕技术的采用通过改变东北地区不同热稳定性的SOM库及其化学成分而改变了其来源


SOM的稳定性和化学组成与老、年轻SOM比例的变化有关。然而，很少有研究探讨免耕（NT）对SOM稳定性、化学成分和来源的影响。在本研究中，确定了 9 年 NT 对总 SOM、热不稳定和稳定 SOM 含量、其化学成分以及 C 和 C 植物的贡献的影响。在施用 NT 之前，该田地在最初的 C 草原开垦后约 80 年一直在常规耕作 (CT) 管理下用于 C 玉米种植。土壤样品采集于 0-20 cm 土壤剖面。 NT处理下，总SOC、热不稳定和稳定SOC以及C-SOC含量随着土壤深度的增加而降低。然而，CT 下 0-10 cm 层的含量大于 10-20 cm 层的含量。两种耕作处理下C-SOC含量均不随深度变化。 NT在0~5 cm土层中总SOC、C-SOC、热不稳定SOC和C-SOC含量高于CT，但在下土层较低。 NT处理下0-5 cm层C-SOC含量下降。烷基-C和O-烷基-C是热不稳定SOM的主要部分，芳香族-C是热稳定SOM的主要部分。 C-SOC（年轻SOC）与烷基-C和O-烷基-C显着正相关，与芳香族-C显着负相关。我们的结果表明：（1）与连续CT相比，施加NT导致SOC在表层积累，（2）更多的玉米残渣输入增加了新的热不稳定且稳定的SOM，但导致NT下的C-SOC降低， (3) C 和 C 驱动的 SOM 的贡献决定了各种 SOM 池的化学组成。