Effect of nitrogen application rate on its fate in “wheat-soil” under different fertility soil conditions

Abstract In order to study the nitrogen application rate in farmland with different fertility levels and the main destination and wheat absorption of N-fertilizer, to improve nitrogen use efficiency, three soils with different fertility levels were selected: chernozems soils (CS)、fluvo-aquic soils (FS) and rougi-limestone soils (RS), were used to study the effects of soil and nitrogen application rate on nitrogen fate of “wheat-soil” under the same ecological environment by isotope tracer technique in this experiment. The results showed that grain yield and nitrogen absorption of wheat in CS which with high fertility and nutrient content were significantly higher than that in FS and RS. Nitrogen fertilizer has a greater impact on the nitrogen content of FS and RS than on black soil. The ability of wheat to utilize residual fertilizer nitrogen in soil is less affected by the amount of nitrogen applied in the last season and is more affected by soil conditions, as CS > FS > RS. After planting two-season wheat, the proportion of nitrogen recovered by the wheat-soil is 37–68%, of which the nitrogen fixed by the soil accounts for 13–32% of the applied nitrogen. The average nitrogen loss of CS is 77.4 kg N·ha− 1, that of FS is 102.9 kg N·ha− 1 and that of RS is 153.1 kg N·ha− 1, indicating that the CS condition is conducive to the absorption of N-fertilizer by wheat, with the least nitrogen loss and the least impact on the environment. When nitrogen application rate from 120 kg·ha− 1 increased to 360 kg·ha− 1, the nitrogen loss rate increased by 6.58 percentage points, but the nitrogen loss increased from 51.5 kg·ha− 1 to 178.2 kg·ha− 1, and the impact on the environment increased significantly. Therefore, we should pay attention to improve soil fertility and structure, and select the appropriate amount of nitrogen according to the actual situation of soil, so as to realize the synergistic improvement of wheat yield and nitrogen utilization, reduce resource consumption and the impact of nitrogen fertilizer on the environment in wheat production.