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以亚热带红壤丘陵区典型旱地和水旱轮作长期定位试验地为研究对象,以单施化肥(NPK)为对照,研究长期秸秆还田配施化肥(NPKS)后农田土壤中纤维素的积累效应及其周年降解特征,并从纤维素降解的关键酶活性、土壤基本性质和气候环境阐明影响农田土壤中纤维素降解的主要因子。结果表明:两种土地利用方式下,长期(13年)NPKS处理后土壤中纤维素积累并不显著;周年变化来看,添加NPKS后旱地和水旱轮作地土壤中纤维素含量分别在施肥后6和3个月内迅速降至施肥前水平,表现为水旱轮作地土壤中纤维素降解速率显著高于旱地;水旱轮作地中纤维二糖水解酶(CBH)及β-葡萄糖苷酶(βG)活性的增量在添加NPKS后均显著高于旱地,说明水旱轮作地中纤维素酶活性对秸秆还田的响应更强;两种土地利用方式下,长期施肥后纤维素占土壤有机质的比例下降,说明纤维素并不是亚热带红壤丘陵区农田土壤有机碳库积累重要的直接组分。相关分析和回归分析结果表明,β-葡萄糖苷酶、土壤微生物生物量碳、碱解氮是影响纤维素降解的主要因子。未来可通过调整施肥、土地利用方式来调控亚热带红壤丘陵区农田土壤有机碳库及其组分的转化过程。
Taking the long-term experiment of typical dryland and arid arid rotation rotations in subtropical red soil hilly region as research object, the effect of cellulose accumulation in farmland soils after long-term straw returning to fertilizers (NPKS) Its annual degradation characteristics, and from the key enzyme activity of cellulose degradation, the basic nature of the soil and the climatic environment to clarify the main factors affecting the degradation of cellulose in farmland soil. The results showed that the accumulation of cellulose in the soil after NPKS treatment for a long time (13 years) was insignificant under the two land use patterns. In the annual variation, the content of cellulose in the soil after the addition of NPKS was higher 6 and 3 months before the rapid decline to pre-fertilization levels, showing the rotation of soil and water in the soil cellulose degradation rate was significantly higher than the dry land; water and drought rotation in the cell cellobiohydrolase (CBH) and β-glucosidase ( βG) activity increased significantly after the addition of NPKS than the dry land, indicating that the rotation of soil and water and cellulase enzyme activity on the response of straw to a stronger; two kinds of land use, long-term fertilization of cellulose accounting for soil organic matter Decreased, indicating that cellulose is not an important direct component of soil organic carbon pool in farmland soil in subtropical red soil hilly region. Correlation analysis and regression analysis showed that β-glucosidase, soil microbial biomass carbon and available nitrogen were the main factors affecting cellulose degradation. In the future, fertilization and land use may be adjusted to control the conversion process of soil organic carbon pool and its components in the farmland in subtropical red soil hilly areas.