Evaluation of the effects of plastic mulching and nitrapyrin on nitrous oxide emissions and economic parameters in an arid agricultural field

Abstract Plastic film has been widely applied to address water shortages by reducing soil evaporation in arid and semi-arid regions, but it simultaneously affects soil nitrous oxide (N 2 O) emissions. Moreover, after the application of plastic film, the ability of nitrification inhibitor to reduce N 2 O emissions remains unclear. In this study, the chamber method was used to measure N 2 O emissions and a modified diffusion equilibrium sampler was used to obtain N 2 O concentrations in an oasis cotton field. Non-mulched and mulched treatments were used to investigate the influence of plastic mulching on soil N 2 O dynamics, and mulched plus nitrapyrin treatment was used to evaluate the ability of nitrapyrin to reduce N 2 O emissions under plastic mulching. Moreover, we also estimated the net economic return and cost related to an eventual environmental taxation on N 2 O emission of these practices. In all treatments, the ridge soil was the origin of most N 2 O (82–87%) emissions, which remained at low levels during the non-fertigation period (ranging from 0.4–17.1 g N ha −1  day −1 ) and sharply increased after the split application of urea; emissions during the fertigation periods accounted for 57–85% of the total N 2 O emissions in all treatments. Compared with the non-mulched treatment, the use of plastic film is a “win-win” strategy for both agricultural income (net economic returns increased by $436–522 ha −1  year −1 ) and N 2 O mitigation (emissions reduced by 19–28%), even without incentives. Although the addition of nitrapyrin to the urea reduced the cumulative N 2 O emissions by 23–39% under plastic mulching, and therefore reduced the costs related to an eventual environmental taxation on N 2 O emission by approximately $2 ha −1  year −1 , this benefit could not compensate for the additional cost of inputting nitrapyrin ($24 ha −1  year −1 ) because this technique did not have a significant effect on cotton yields. Therefore, the use of nitrapyrin is probably a “lose-win” strategy for farmers and N 2 O mitigation and not suitable for reducing N 2 O emissions in oasis cotton fields.