Impact of incorporation of rice straw into the soil on soil fertility and yield

Eighteen years of rice straw incorporation experiment and three years of field experiment show that straw incorporation into the soil can improve soil fertility and significantly increase yield.Grain yield of fertilized soil with rice straw is 80.8% higher than that of CK,but no significant yield difference exists between NPK fertilization with rice straw incorporation and NPK fertilization alone in the 12-year(long-term)experiment.In the 3-year(short-term)field experiment,rice straw incorporation increases grain yield by 3.7%～ 6.8%.N fertilization significantly increases rice yield and the rates of increase of grain yield by recommended N and farmer-applied N are 38.8% and 47.4%,with agronomic efficiencies of 13.7 kg and 11.7 kg grain per kilogram N fertilizer,respectively.Fertilizer benefit ratio decreases with increasing N fertilization.Economic analysis shows that use of straw residue along with recommended N fertilizer reduces fertilizer cost,and concomitantly improves economic efficiency.