Mechanisms underlying nitrous oxide emissions and nitrogen leaching from potato fields under drip irrigation and furrow irrigation

Irrigation methods can affect nitrogen loss in agricultural soil. Exploring the effects of different irrigation methods on soil nitrogen losses in arid areas can provide a basis for more effective water and fertilizer management. A 2-year field experiment was performed, using a static chamber and soil solution extractor, to quantify nitrous oxide (N2O) emissions and nitrogen leaching from upland soils during various potato plant growth stages. The treatments included drip fertigation without fertilizer, drip fertigation + 500 kg N /hm2, drip fertigation + 1000 kg N /hm2, furrow irrigation without fertilizer, furrow irrigation + 500 kg N /hm2, and furrow irrigation + 1000 kg N /hm2. N2O emissions and nitrogen leaching were significantly different at the different potato growth stages (P＜0.01). Under both irrigation methods, the peak N2O emissions appeared during the tuber setting and swelling stages, and the total emission ratios of the two stages under each treatment in these two periods were 56–89% in 2018 and 2019. Nitrogen dioxide (NO2−) plays a crucial role in N2O emissions. A significant peak in N2O emissions was found to be related to the existence of NO2−. The correlation coefficient between NO2− concentration and N2O emissions reached 0.6413 (P＜0.05). Leaching losses also peaked during the tuber setting and swelling stages, with ratios of 51.14–84.22%. Compared with furrow irrigation, the N2O emissions from drip irrigation were decreased by 34.10–81.36%, nitrogen leaching decreased by 35.26–68.35%, and the N2O emission intensity decreased by 40.0–86.9%. Drip irrigation can effectively decrease nitrogen losses, and is an effective strategy to save water, to mitigate the emission of atmospheric pollutants such as N2O, and reduce nitrogen leaching.