Simulation Effect of Water and Nitrogen Transport under Wide Ridge and Furrow Irrigation in Winter Wheat Using HYDRUS-2D

Abstract

An experiment was conducted to create a science-based program of irrigation and fertilizer application for two-year winter wheat under wide ridge and furrow irrigation in the Yellow River irrigation area. The study was performed in a test field located in Zhengzhou, Henan Province, China. A numerical model of soil water and nitrogen transport for winter wheat under wide ridge and furrow irrigation was created using HYDRUS-2D. The behavior of soil water and nitrogen was predicted for different irrigation water and nitrogen treatments and analyzed to identify pathways of nitrogen transport and transformation. The nitrogen balance was calculated for the different water and nitrogen treatments. The coefficients of determination for measured and predicted values of soil water content, nitrate nitrogen, and ammonium nitrogen in both horizontal and vertical directions were all >0.68; the mean absolute error was <0.06; and the root mean square error was <0.1. These values indicate the feasibility of using a numerical model of nitrogen transport for wide ridge and furrow irrigation. The correlation coefficient R2 between simulated values of nitrogen uptake and measured values of total crop nitrogen content was 0.88, the RMSE value was 10.58 kg/ha, and the MAE value was 5.9 kg/ha. Nitrogen loss was primarily caused by denitrification, and the quantity of gaseous nitrogen loss was 7.05–38.2% of the nitrogen form. The total quantity of ammonium nitrogen absorbed by winter wheat plant roots in each treatment was 7.6–15.1% of the total amount of nitrate nitrogen absorbed. The maximum nitrogen uptake was 155.53 kg/ha with a yield of 6888.67 kg/ha at a nitrogen application rate of 220 kg/ha and irrigating to 70% field capacity. The UE of the 220 kg/ha and irrigating to 70% field capacity treatment was relatively high, the PFP of the 120 kg/ha and irrigating to 80% field capacity treatment was relatively high, and the nitrogen use efficiency of the 320 kg/ha and irrigating to 60% field capacity treatment was the lowest overall. This study provides a basis for investigating soil water and nitrogen transport mechanisms of winter wheat under wide ridge and furrow irrigation in the Yellow River irrigation area.