Effects of long-term fertilization on rice yield and contribution rate of basic soil productivity on the yellow paddy of southern China

Effects of 27-year consecutive fertilization on rice yield and the contribution rate of basic soil productivity were studied on the southern yellow paddy.The result indicated that the application of chemical fertilizer(NPK),NPK and cattle manure(NPKM) or NPK and straw(NPKS) increased the crop yield by 74.9%,96.6% and 91.7%,respectively,as compared to non-fertilization(CK).The yields on land applied with NPKM and NPKS increased by 12.4% and 9.6%,respectively,as compared to NPK.The differences were all highly significant.But the difference between the yields from the rice yields applied with NPKM and those applied with NPKS were not significant.During the double-cropping period between 1983 and 2004,the year-on-year growth rate per 5-7 years showed a steady trend of increase by applying NPK,NPKM or NPKS.The contribution rates of basic soil productivity for the early and late rice showed a fluctuating but constant decreasing trend over the years.The mean contribution rates for the early and late rice were 47.1 and 60.0,respectively.The rice yields associated with different fertilization correlated significantly,or very significantly,with the basic soil productivity.