Effects of Straw Alternative Returning on Soil Fertility and Available Nutrients in Wheat Field under Rice-Wheat Rotation System

[Objective]The purpose of this study was to investigate the effects of rice and wheat straw-returning on soil fertility and available nutrients in wheat field.[Method] Under rice-wheat double cropping system,three treatments of straw application,rice-straw(RS) and wheatstraw(WS) returning in single season,rice-wheat straw(WR) returning in double season and no straw application(CK) were conducted.Nitrate and ammonium nitrogen,available phosphorus and available potassium in wheat field were determined.[Result] The results suggest that straw-returning could improve soil fertility through increase of organic matter,total nitrogen and available nutrients in wheat field.The contents of available nutrients were increased in varying degrees during what growing.The straw-returning make full use of the complementary role of available nutrients supply in wheat field.Moreover,the straw-returning enhanced available nutrients supply at middle and late stages of wheat growth so as to lay a good foundation for soil fertility in next season.The increasing was obvious under the treatment of rice-straw returning in single season and rice-wheat straw returning in double season.[Conclusion]The study can provide a scientific basis for high yield cultivation of wheat and scientific straw-returning.