Optimization of drip fertilization practice for winter wheat−summer maize farmland using the DNDC model

Objectives Drip fertigation is considered an efficient strategy for water and nutrient application during crop production which could save water and fertilizers, but uncertainty around the effects of greenhouse gas emission and economic benefit. Optimizing the strategy of drip fertigation for winter wheat-summer maize rotation system in north China is of great significance to increase water and fertilizer use efficiencies, reduce environment pollution and improve economic benefit.

Methods Field experiments were carried out in Huantai County of Shandong Province. Three N fertilizer rate treatments and five irrigation amount treatments were conducted to investigate the effects of different nitrogen fertilizer management and drip irrigation management on crop yields and N₂O emission in the winter wheat-summer maize system. Measured data were used to calibrate the DNDC model, and then the DNDC model was employed to optimize drip fertigation schedule under winter wheat-summer maize rotation system in the North China.

Results Based on comprehensive consideration of crop yields and N₂O emission, the modified DNDC quantified the effects of different drip irrigation scenarios on N₂O emission, and put forward the optimal drip fertigation strategy. The drip irrigation amount was 130 mm, and the nitrogen application amount was N 189 kg/hm² in winter wheat season, while the drip irrigation amount was 19.2 mm, and the nitrogen application amount was N 231 kg/hm² in summer maize season. Dripping water with fertilizers was applied 4 times during the winter wheat and summer maize growing seasons respectively, which could reduce 16% N₂O emission in comparison to the optimal drip fertigation strategy ripe-rot by field trials without reducing the yields.

Conclusions The optimized strategy of drip fertigation can save 58.6% of irrigation water, 30.0% of N fertilizer and reduce 50.0% of N₂O emission in comparison to the conventional water and N treatment. The net income and rate of return on the increased investment of change from conventional irrigation and fertilization to optimized drip fertilization was 1336.41 yuan/hm² and 230.34%. The optimized drip fertilization should be feasible for farmers to accept according to the criteria for partial budget analysis. This study provides a useful reference for the efficient agricultural management of saving water and fertilizer, reducing greenhouse gas emission, and increasing economic benefit in the North China Plain.