Effects of drip system uniformity and nitrogen application rate on yield and nitrogen balance of spring maize in the North China Plain

• Field experiments of maize under drip irrigation were conducted in the North China Plain.
• The effect of drip uniformity on yield and apparent nitrogen loss was not significant.
• High nitrogen soil fertility reduced the effect of nitrogen fertilizer on spring maize yield.
• Lower nitrogen application rate is helpful for reducing nitrogen losses.

The effects of drip system uniformity and nitrogen application rate on spring maize growth, nitrogen uptake, yield, yield components, nitrogen agronomic efficiency, and apparent nitrogen loss were investigated through field experiments to modify the current design and evaluation standards for drip system uniformity. The experiments were conducted in the North China Plain during two growing seasons of spring maize (Zea mays L.) in 2011 and 2012 using 27 experimental plots of 30 m long and 3 m wide. Three Christiansen uniformity coefficients (CU) of 59, 80, and 97% and three levels of nitrogen applied at 0, 120, and 210 kg ha−1 were tested. The results demonstrated that the drip system uniformity had an insignificant effect on plant growth, plant nitrogen uptake, yield, yield components, nitrogen agronomic efficiency, and apparent nitrogen loss at a significance level of p < 0.05. The influence of nitrogen application rate on plant growth, plant nitrogen uptake, and yield was related to the initial nitrogen content in the soil. High nitrogen soil fertility reduced the effect of nitrogen fertilizer on crop yield. The apparent nitrogen loss increased significantly with nitrogen application rate whereas the difference of yields between the treatments with nitrogen applied at 120 and 210 kg ha−1 did not reach a statistical significance. In the subhumid region of the North China Plain where irrigation only accounts for 21–23% of the precipitation during the growing season of maize, a drip system uniformity that is lower than the values recommended by the current standards might be used to reduce the installation and operation costs of drip irrigation systems. Using a nitrogen application rate that is lower than the conventional values (e.g., 210 kg ha−1) is a promising practice to reduce nitrogen losses while maintaining an acceptably high level of yield.