中文摘要：

通过红壤区水稻试验，分析了长期使用氮磷钾肥条件下双季水稻的生物量（包括稻谷产量和秸秆量）、养分增产效应和土壤肥力的变化。氮磷钾肥的配合施用对双季水稻生物量的影响顺序为NPK〉NP〉PK〉NK〉CK。N、P、K对水稻的增产效应系数分别为41．2％～54．8％、66．3％～88．2％和10．3％～10．9％。N、P和K增产效应的变异系数规律与其增产效应相反，说明养分对双季水稻增产效应越高，其稳定性越好。双季水稻的增产效应及其稳定性均表现为早稻优于晚稻。氮磷钾肥的配施可显著提高土壤有机质和全氮含量。磷肥的使用明显增加了土壤全磷和有效磷含量。钾肥使用提高了土壤全钾和交换性钾含量，然而水稻生物量的输出却与之相反，两者的平衡决定着土壤全钾和交换性钾含量的变化。氮磷钾肥对土壤pH值影响则不一致，氮肥（尿素）的长期使用降低土壤pH值，而磷肥（钙镁磷肥）的使用减缓了土壤pH值的降低。

英文摘要：

Changes of rice biomass （including grain and straw yields）, yield-increasing effect of nutrient and paddy soil fertility were investigated in a long-term NPK fertilization experiment under a double-cropping system. The effects of N, P and K fertilization at different ratios on total rice biomass were ranked as follows： NPK〉NP〉PK〉NK〉CK. The yield-increasing effects of N, P and K on rice biomass were 41.2%--54.8% ,66.3%--88.2% and 10.3%--10.9%, respectively. The coefficients of variance of yield-increasing effect on rice biomass for N, P and K were reversely varied with their yield-increasing effect. It illuminated that the higher the yield-increasing effect on rice biomass was, the better its stability was. Early rice was obviously better than later rice with respect to the yield-increasing effect and its stability. The application of N, P and K fertilizer could markedly enhance the concentration of soil organic matter and total N in soil. The phosphorus fertilization significantly increased the content of total P and available P in soil. The potassium fertilizer application enhanced the concentration of total K and exchangeable K content in soil, however, the output of rice biomass significantly reduced. In fact, the balance between input and output of K limited the changes of total K and exchangeable K content in soil. The application of N, P and K fertilizer discordantly affected soil pH value, the N fertilization （urea） decreased soil pH value, whereas the P fertilization （calcium magnesium phosphate） slowed the soil pH value decline.