Abstract: In order to provide theoretical basis for returning total wheat straw on rice production,a field experiment was conducted to study effect of ensuing nitrogen application after return of total wheat straw on rice yield and soil mineral nitrogen dynamics.Results show that with the total N application rate kept the same,Treatment RTWS(return of total wheat straw) significantly increased rice yield,and in Treatment RTWS,nitrogen application model B had a better yield-raising effect than model A.The experiment was designed to have nitrogen application split into 5∶5 between basal-tillering fertilizer and earing fertilizer,and 6∶4 between basal fertilizer and tillering fertilizer for Model A and into 6.5∶3.5 and 8∶2,respectively,for Model B,which is a modified one over on the basis of the former.Analysis of soil mineral nitrogen dynamics revealed that Treatment RTWS decreased NH4+-N and NO3——N contents in the soil before the rice booting stage,but increased the content of the latter afterwards,and that NO3——N content was higher with Model B than with Model A at any rice growth stage.Compared with CK(no wheat straw returned),Treatment RTWS inhibited rice growth and nitrogen uptake before the booting stage,but acted reversely after the stage.However,in Treatment RTWS,Model B had higher rice biomass and rice nitrogen uptake than Model A at any rice growth stage.With the total N application rate set at 270 kg·hm-2,Treatment RTWS coupled with Model B increased rice yield by 9.3% and by 5.3%,respectively,over Treatment TRWS coupled with Model A and CK.Although effective ears,grain weight and grains are major rice yield composition factors,Treatment RTWS increased mainly number of effective earings,by 6.1% to 14.5% over CK,thus improving the yield.Therefore,return of total wheat straw coupled with Model B in nitrogen application is an effective measure for higher rice yield.

Key words: wheat, straw returning, rice yield, nitrogen application model, soil mineral nitrogen