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研究使用常规犁耕-休闲(DTF),常规犁耕-小麦(DTW),保护耕作-休闲(CTF),保护耕作-小麦(CTW)4个处理,评价连续实验10a后保护性耕作对稻作区SOM的影响。结果表明:垄作、免耕和小麦种植的结合是稻作区一种较好的保护性耕作实践。它不仅显著增加SOM在土壤表层的聚集,而且它也通过改变SOM的组成和结构显著影响土壤胡敏酸的光谱和热解特性。相比其他处理,垄作免耕(稻麦)在0～10cm土层拥有最多的SOM含量,但随着土层厚度的增加,这一含量下降的也较为迅速。垄作免耕(稻麦)土壤胡敏酸在波长665nm处的光密度为0.122,465nm处为0.705,而常规平作(中稻)在这两个波长处却分别为0.062和0.321。垄作免耕土壤胡敏酸DTA曲线在360～365℃处放热峰的焓变值比常规平作低,1000～1050cm-1吸收峰常规平作也比垄作免耕强。垄作免耕土壤腐殖质的氧化稳定系数增高,表明长期垄作免耕土壤腐殖酸的缩合度增高,芳构化程度增强。通过保护性耕作和作物实践可以管理稻田土壤,维持充分的SOM积累,缓解土壤有机碳的丢失。
Four treatments of conventional plow-leisure (DTF), conventional plowing-wheat (DTW), conservation tillage-leisure (CTF) and conservation tillage- District SOM impact. The results showed that the combination of ridge cultivation, no-tillage and wheat cultivation was a good conservation tillage practice in the paddy field. It not only significantly increases the SOM accumulation on the soil surface, but it also significantly affects the spectral and pyrolytic properties of soil humic acid by changing the composition and structure of SOM. Compared with other treatments, ridge-free no-tillage (Oryza sativa L.) had the most SOM content in 0 ~ 10cm soil layer, but decreased rapidly with the increase of soil thickness. Soil humic acid in ridge-free tillage (rice and wheat) soil had an optical density of 0.122 at a wavelength of 665 nm and 0.705 at a wavelength of 465 nm, whereas conventional flat rice (middle rice) was 0.062 and 0.321 at these two wavelengths, respectively. The change of enthalpy of exothermic peak of humic acid DTA curve in no-tillage soil at 360 ~ 365 ℃ was lower than that of conventional flat, and the absorption peak of 1000 ~ 1050cm-1 was also better than that of ridge-tillage. The oxidation stability coefficient of humus in ridge-free no-till soil increased, indicating that the condensation degree of humic acid in long-term ridge-free no-tillage soil increased and the degree of aromatization increased. Paddy soil can be managed through conservation tillage and crop practices to maintain adequate SOM accumulation and mitigate the loss of soil organic carbon.