Abstract:In order to clarify the effects of reduced nitrogen fertilization on wheat yield, nutrient uptake and soil physicochemical properties under rice straw returning, a field experiment was conducted with the wheat variety “Ningmai 16” as test material. The treatments were designed as follows: 1) nitrogen application: no nitrogen application control (CK), constant nitrogen application of 225 kg/hm2 (N1), reduced nitrogen application of 180 kg/hm2 (N2); 2) nitrogen management: the ratio of base fertilizer to topdressing is 5︰5 (M1) and 7︰3 (M2). Wheat yield and its components, nutrient absorption and distribution, nitrogen use efficiency and soil physicochemical properties were measured and analyzed. The results show that wheat yield of N2 is only 80.72 kg/hm2 lower than that of N1. Increasing the proportion of basic nitrogen application increases the number of effective panicles per unit area. Nitrogen application significantly promotes the absorption of nitrogen, phosphorus and potassium in wheat grains, straws and shoots. The absorption of nitrogen, phosphorus and potassium of N2 are lower than those of N1. At N1 and N2 levels, nitrogen and phosphorus uptake of M2 are higher than those of M1, while potassium uptake of M2 is lower than that of M1. Nitrogen application significantly increases wheat yield. Nitrogen agronomic efficiency, nitrogen partial productivity, nitrogen apparent efficiency and nitrogen physiological efficiency of N2 are higher than those of N1, while nitrogen uptake of 100 kg grain is decreased. The content of available nitrogen of N1 is significantly higher than that of CK. The contents of organic matter, available nitrogen and available potassium of N2 are lower than those of N1, while the content of available phosphorus is higher than that of N1. At N1 and N2 levels, the contents of organic matter and available nitrogen of M1 are higher than those of M2, while the contents of available phosphorus and available potassium of M2 are higher than those of M1. In general, under the condition of returning rice straw to the field, reducing conventional nitrogen application by 20% and appropriately increasing the proportion of basic nitrogen application can increase the number of effective panicles per unit area, achieve high and stable wheat yield, and improve nitrogen use efficiency.