中文摘要：

观测分析了黑土长期不同施肥30年后不同形态的活性有机碳含量（易氧化有机碳〉轻组有机碳〉微生物量碳〉水溶性有机碳）的变化特征。结果表明，长期施用氮、氮磷和氮磷钾化肥对土壤活性有机碳无显著影响；长期施用有机肥以及有机肥配施化肥均显著提高了土壤活性有机碳含量，与不施有机肥相比，有机肥区组中土壤轻组有机碳和水溶性有机碳含量增幅较大，分别在122％～258％和237％-351％之间，而土壤易氧化有机碳和微生物量碳含量增幅分别在72％-98％和83％-112％。黑土不同形态活性有机碳对施肥的响应灵敏度为，轻组有机碳〉水溶性有机碳〉微生物量碳一易氧化有机碳。因此，轻组有机碳是指示土壤有机碳变化的较好指标。

英文摘要：

The characteristics of soil organic carbon and active organic carbon under 30-yr long-term fertilization were investigated in a black soil located in Jilin Province, northeastern China. Results showed that the contents of different active organic carbon were in decreasing order of labile organic carbon （LOC）〉 light fraction organic carbon （LFOC）〉 microbial biomass carbon （MBC）〉 water soluble organic carbon （WSOC）. Application of chemical fertilizer alone had little influence on soil organic carbon （SOC） and active organic carbon, while applications of manure and manure plus chemical fertilizers significantly increased SOC and active organic carbon. With manure and manure plus chemical fertilizers application, LFOC and WSOC contents were significantly increased by 122% - 258% and 237% - 351%, whereas LOC and MBC increased by 72% - 98% and 83% - 112%, respectively,compared with that chemical fertilizers alone. The sensitive responses of different active organic carbons to longterm fertilizations were observed in the following order： LFOC〉WSOC〉MBC ≈ LOC. LFOC was the best indicator among the available carbon fractions to indicate the SOC change in black soil under long-term fertilization.