Innovative nitrogen management strategy reduced N2O emission while maintaining high pepper yield in subtropical condition

High N fertilizer inputs in subtropical vegetable systems under the warm and humid climatic conditions increase the risk of nitrous oxide (N2O) emissions. However, there is limited information available on integrated N management strategies to reduce N2O emissions from intensive open-field vegetable systems in subtropical region. Two plot-based field experiments were conducted in subtropical southwest China to examine the effects of different N management strategies on N2O emissions from a typical open-field pepper (Capsicum annuum L.) production system. Experiment 1 included five N rates (0, 175, 250, 325, and 400 kg ha-1) with conventional urea. Experiment 2 included a 0 N control and four N sources (conventional urea, organic fertilizer, nitrification inhibitor-based enhanced efficiency fertilizer ENTEC26, and controlled release urea) applied under an optimized N rate (250 kg N ha-1). The results of Experiment 1 showed that cumulative N2O emission and emission factor were 4.05 kg N ha-1 season- 1 and 0.96%, respectively, under the conventional management (N400). N2O emissions increased exponentially with increasing N rates. Compared to the N400 treatment, application of conventional urea at the optimal rate (250 kg N ha-1) significantly reduced cumulative N2O emissions by 54% while maintaining similar pepper yield. The results from Experiment 2 indicated that the use of enhanced efficiency fertilizers at the optimal rate further reduced N2O emission by 30%- 50% compared to conventional urea, while increasing pepper yield by 6.7%- 9.0%. This resulted in a 36%- 53% reduction of yield-scaled N2O emission intensity. In particular, the use of nitrification inhibitor was 28% more effective than controlled release urea for N2O mitigation. These results suggest that the application of enhanced efficiency fertilizers at an optimum N rate could produce more vegetables while reducing N2O emission, thereby promoting sustainable vegetable production in the subtropic regions.

Automated summary

High nitrogen inputs in subtropical vegetable systems increase nitrous oxide (N2O) emissions, but there is limited information on N management strategies in these systems. Two field experiments were conducted in southwest China to investigate the effects of different N management strategies on N2O emissions from a pepper production system. The results showed that the use of enhanced efficiency fertilizers at an optimum N rate reduced N2O emissions and increased pepper yield, promoting sustainable vegetable production in subtropical regions.