Effects of Wheat Straw Returning and Nitrogen Application Model on Rice Yield and Soil Nitrogen Supply

In order to provide a theoretical basis for total wheat straw returning on rice production, a field experiment was conducted to study the differences of rice yield and soil nitrogen supply under different nitrogen application models after total straw returning. Nitrogen application model A was the traditional fertilization method, nitrogen application model B was the optimum model of A. Nitrogen quantity between basic tiller fertilizer and panicle fertilizer, base fertilizer and tillering fertilizer in model A were 5:5 and 6:4, while B were 6.5:3.5 and 8:2, respectively. Results showed that total wheat straw returning significantly increased rice yield, and model B had a higher production rate than model A, 9.3% and 5.3% higher than CK, respectively. Straw returning increased rice yield mainly by promoting seed-setting rate, spike-formed rate and effective panicles. Compared with CK, straw returning treatments inhibited before booting stage but promoted after booting stage the rice growth and nitrogen accumulation. Nitrogen application model B had higher rice biomass and nitrogen accumulation than model A at same rice growth period. According to soil mineral nitrogen dynamics, straw returning treatments decreased before rice booting stage but improved after booting stage the mineral nitrogen contents, and with model B of higher contents than model A at the same rice growth period. Straw returning significantly increased nitrogen recovery efficiency, RNA and RNB were 9.3 and 5.3 percentage point higher than CK, respectively. Soil nitrogen apparent budgets were presented as RNBRNACK. Therefore, total wheat straw returning with nitrogen application model B was an effective measure for promoting rice high yield and keeping soil nitrogen balance.