Study on corp yield stability in a typical region of rice–wheat rotation based on long-term fertilization experiment

To investigate the ways of maintaining high and stable crop yield under long-term fertilization, a long-term field experiment was set up in 1980 in a typical rice-wheat rotation region-the Taihu Lake Region. The changes of rice and wheat yield and soil nutrient under term fertilization in different years, the crop yield stability and the relationship between crop yield and soil organic carbon and nitrogen were analyzed. Results showed that during the period of long-term experiment, the yields of rice and wheat in different treatment plot fluctuated and varied greatly among different years affected by climate and other factors. From statistic results of long-term experiment, increased trends of the yields of wheat and rice were found among different years. The increasing trend of rice yield was more significant than wheat, and yield of wheat fluctuated comparatively larger than rice. Effects of organic manure and crop straw treatments on increasing crop yield were more significant than chemical fertilizer treatments. Yield stability of rice was higher than that of wheat, CV of rice was lower and SYI of rice was higher than that of wheat respectively. The highest yield stability was found in treatment MPK (Manure and fertilizer P, K), but the lowest of that was found in treatment MNPK (Manure and fertilizer N, P, K). Amendments of chemical fertilizer, especially nitrogen fertilizer may lead to decline of crop yield stability. Nitrogen fertilizer was the major factor of yield increasing, but may lead to lower stability of paddy ecosystem. Correlation between crop yield and level of soil nitrogen was more significant. Compared to dry season, yield stability and increasing of wheat was more significant in wheat season, indicated a higher sustainability of paddy soil ecosystem which may be improved with years of cultivation.