Spatial–temporal distribution characteristics of water-nitrogen and performance evaluation for basin irrigation with conventional fertilization and fertigation methods

Basin irrigation experiments were performed using conventional fertilization and fertigation methods under different inflow rate during the reviving irrigation of winter wheat. The spatial–temporal distribution of nitrogen in the basin surface water flow and soil with different fertilization methods was analyzed, the factors affecting the distribution uniformity of nitrogen in soil after irrigation were discussed, and the fertilization performances of basin irrigation with different fertilization methods were evaluated. Results showed that fertilization methods can significantly affect nitrogen distribution. The spatial–temporal distribution difference of nitrogen in surface water flow is small for fertigation, but is big for conventional fertilization. The spatial distribution uniformity of nitrogen in soil after irrigation can be improved for fertigation, and the coefficient of variation CV is about 0.07 within a soil depth of 1 m, which is much smaller than that in conventional fertilization. Both the fertilization method and discharge can significantly affect nitrogen distribution uniformity, nitrogen efficiency, and nitrogen adequacy. The values of all indicators for fertigation are, by average, higher by 14.5, 14.3, and 8.4 percent than the corresponding values for conventional fertilization. For the local basin section, significant differences in nitrogen distribution uniformity between large and small discharge exist for fertigation, and the large discharge is, by average, higher by 4.2 percent than the small discharge. For the entire basin, significant differences in all indicators between small and large discharge exist for conventional fertilization, and the small discharge is, by average, higher by 5.5 percent than the large discharge in nitrogen distribution uniformity, and higher by 5.3 and 3.2 percent in nitrogen efficiency and nitrogen adequacy, respectively.