中文摘要：

以稻田22a施肥定位实验为样地，分别采用硫酸和盐酸加热水解两种方法，研究施肥对水稻土有机碳活性和难降解性组分的影响。施肥处理包括不施肥对照（CK）、单施氮肥（N）、单施磷肥（P）、单施钾肥（K）、氮磷肥混施（NP）、氮钾肥混施（NK）、氮磷钾肥混施（NPK）、双倍氮磷钾肥混施（2NPK）、氮磷钾和有机肥配施（NPK＋OM）。结果表明，两种酸解法获得的有机碳组分结果趋势一致，所得结果高度相关（P〈0．05）。与对照相比，施肥总体上有助于土壤总有机碳的积累；除了单施钾肥处理外，其他施肥处理均提高了土壤活性有机碳的含量，但单施氮及NPK＋OM处理显著提高了土壤有机碳活性指数（LI，），并以NPK＋OM的促进作用最显著（P〈0．05）。与对照相比，除了单施氮处理外，其他施肥处理下土壤难降解有机碳（酸解残余碳）含量均呈增加趋势，也以NPK＋OM的作用最明显（P〈0．05）；单施钾肥显著提高有机碳的难降解性（P〈0．05），但单施氮和NPK＋OM处理显著降低有机碳的难降解性指数（RIc，P〈0．05）。施氮肥和有机肥对土壤总有机碳含量的促进作用主要体现在对活性有机碳的贡献上。因此，可以通过优化施肥措施（如选择合适有机肥种类、减施氮肥和增施钾肥等）来调控水稻土有机碳的含量及稳定性。

英文摘要：

Effects of fertilization for 22 years on labile and recalcitrant fractions of organic carbon of red paddy soils were analyzed with two heated acid hydrolysis methods using H2SO4and HC1, respectively. The long-term fertilization experiment was designed to have 9 treatments, i. e ： （ 1 ） CK, （2） N, （3） P, （4） K, （5） NP, （6） NK, （7） NPK, （8） 2NPK,and （9） NPK ＋ OM. Results showed that the results of fraetionation of organic carbon with the two hydrolysis methods were highly correlated. Compared with CK, fertilization on the whole contributed to accumulation of total organic carbon in paddy soil. The content of labile organic carbon increased in all the treatments, except Treatment K. Labile index （ LIc ） of organic carbon significantly （p 〈 0. 05 ） increased, in Treatment N and Treatment NPK ＋ OM, and especially in the latter. The content of recalcitrant organic carbon, residual carbon from acid hydrolysis increased somewhat in all the treatments, except Treatment N, with Treatment NPK ＋ OM being the most significant （p 〈 0.05） , while Recalcitrance index （ RIc ） , rose significantly in Treatment K but fell significantly in Treatments N and NPK ＋ OM （p 〈 0.05）. Obviously the contribution of N fertilizer and organic manure to total organic contents is mainly embodied in increase in labile organic carbon. Therefore, the findings imply that content and stability of organic carbon in red paddy soil can be manipulated by optimizing fertilization practices, possibly through selecting appropriate organic amendments, reducing N fertilization and enhancing K fertilization.