Five-year controlled-release/stable nitrogen fertilization reduces field nitrogen loss without increasing carbon dioxide emissions in a vegetable rotation system

Controlled-release/stable nitrogen (N) fertilizers can improve vegetable yields and achieve lower greenhouse gas emissions, resulting in cost-effective and environmentally friendly vegetable production. However, there has been limited research on the controlled-release/stable N fertilization in long-term fixed-position vegetable rotation fields. In this study, a five-year field experiment was conducted to examine the effects of long-term controlled-release/stable N fertilization in reducing greenhouse gas emissions and increasing lettuce yield. Six distinct treatments were employed for N fertilization: the control without N fertilizer (CK), normal local farming practices with application of urea fertilizer at 400 kg N ha^-1 (T1), optimized application of urea at 320 kg N ha^-1 (T2), optimized application of urea at 320 kg N ha^-1 with supplementation of 1.0 kg ha^-1 3,4-dimethylpyrazole phosphate (DMPP) as N inhibitor (T3), application of polyurethane-coated urea at 320 kg N ha^-1 (T4), and application of polyurethane-coated urea at 320 kg N ha^-1 with supplementation of 1.0 kg ha^-1 DMPP (T5). The results showed that the T3, T4, and T5 treatments using controlled-release/stable N fertilization emitted about 12.2%–56.7% less average annual cumulative nitrous oxide (N₂O) and 1.31%–10.0% less carbon dioxide (CO₂) than the T2 treatment. Nitrous oxide and CO₂ emissions from the T4 and T5 treatments were considerably lower than those from the T3 treatment. No significant seasonal or interannual variability was observed in N₂O and CO₂ emissions. The observed phenomena were attributed to the fluctuations in soil ammonium- and nitrate-N contents. The findings in this study revealed that long-term controlled-release/stable N fertilization resulted in reduced field N loss, benefitting vegetable yields without increasing CO₂ emissions and highlighting the application potential of this technique for sustainable agricultural production.