Effects of Straw Returning for Successive Years on Yields of Rice and Rape under Different Water Condition

[Objective] The study was to provide the theoretical basis for rational utilization of straw resources.[Method] With different rice and rape varieties as the materials and the treatment without straw application as CK,the effects of straw returning for successive years on yields of rice and succeeding rape under the conditions of none-water layer irrigation cultivation and conventional flooded cultivation were studied.[Result] Under conventional flooded cultivation condition,rice yields in treatments of wheat straw and rape straw mixed with soil were increased by 5.9%-7.2% that that of CK in the first year,but rice yields of the 2 treatments in the second,the third and the fourth year were decreased by 6.7%-8.0%,16.0%-17.9% and 22.6%-23.9% than that of CK resp..Under none-water layer irrigation cultivation condition,rice yields in treatments with straw returning were increased by 6.3%-11.5% than that of CK in the first year,but rice yields of the treatments in the second,the third and the fourth year were decreased by 0-21.3%,2.1%-2.8% and 9.6%-11.6% than that of CK resp.Rape yields in treatments with straw returning were increased by 1.8%-9.3% than that of CK,and those in the second and the third year were increased by 4.3%-10.6% and 5.9%-14.1% than that of CK resp..[Conclusion] After straw returning,rice yield was increased in the first year.After straw returning for successive years,rape yield increased year by year.