Abstract:In order to explore the comprehensive impact of straw returning with stable nitrogen fertilizer on crop growth and water and nitrogen utilization of wheat maize rotation system in Guanzhong region, and determine reasonable high-yield and efficient fertilization management measures, two straw returning modes (no straw returning, full straw returning) and two nitrogen application measures (conventional urea and reduced application of stable nitrogen fertilizer) were set up in a completely random combination, and straw free returning and no fertilization were set as control, a total of five treatments were set to study and analyze crop yield, aboveground biomass, soil ammonia volatilization accumulation, soil moisture content, soil nitrate nitrogen residue and water and nitrogen utilization efficiency. The results showed that straw returning to the field could significantly increase the yield of summer maize and winter wheat by 28.03%~39.63% and 90.10%~112.52%, respectively, and increase the aboveground biomass by 27.88%~34.00% and 78.96%~107.64%. The application of stable nitrogen fertilizer reduced the soil ammonia volatilization accumulation by 50.18%~59.32% and 68.21%~73.43% during the whole growth period of summer maize season and winter wheat season respectively compared with the application of conventional urea. Straw returning to the field could significantly increase the soil moisture content of 0~10cm soil in summer maize season by 6.29%~21.38%, and that of 0~10cm soil in winter wheat season by 6.80%~25.06%. Under the same fertilization measures, straw returning to the field could significantly reduce the NO-3N residues in the 0~100cm soil of summer maize and winter wheat at harvest time by 7.34%~10.78% and 6.57%~11.24%. Under the same straw returning mode, the application of stable nitrogen fertilizer could significantly reduce the NO-3N residues in the 0~100cm soil of summer maize and winter wheat at harvest time by 28.96%~31.63% and 4.16%~9.54% compared with that of application of urea. Under the same fertilization measures, straw returning significantly improved water use efficiency, nitrogen partial productivity and nitrogen agronomic efficiency in summer maize season and winter wheat season by 4.55%~7.85%, 5.79%~12.08%, 25.22%~41.43% and 7.36%~9.73%, 2.25%~14.38% and 4.33%~30.35%. Under the same straw returning mode, the application of stable nitrogen fertilizer significantly improved the partial productivity of nitrogen fertilizer, agronomic efficiency of nitrogen fertilizer, nitrogen absorption efficiency, nitrogen recovery efficiency of 43.75%~52.29%,42.01%~60.39%, 62.07%~66.67%, 52.50%~72.73% and 21.93%~36.41%, 11.37%~39.14%,50.67%~53.85%, 60.00%~64.15%, respectively, in summer maize season and winter wheat. Therefore, straw returning with stable nitrogen fertilizer would significantly improve water and nitrogen use efficiency of wheat maize rotation system, reduce nitrogen volatilization loss and nitrogen leaching risk. Based on comprehensive consideration, 180kg/hm2 stable nitrogen fertilizer and 150kg/hm2 stable nitrogen fertilizer were reasonable fertilization measures for realizing high yield and efficiency of summer maize and winter wheat in Guanzhong area.
