N2O emissions from banana plantations in tropical China as affected by the application rates of urea and a urease/nitrification inhibitor

Abstract

In this study, we quantified N2O fluxes from banana plantations in China using a field experiment as well as static chamber and gas chromatography techniques. We utilized five levels of urea treatments, including CK (no urea addition); urea addition at a rate of 312 (U1), 415 (U2), 519 (U3), and 623 kg N ha−1 (U4); and a combination of urea (U3) and urease (NBPT) and nitrification (DCD) inhibitor (U3 + I) treatments. Soil temperature, moisture, and the concentrations of NH4 + and NO3 − have been monitored throughout the study. Compared to CK (11.8 μg m−2 h−1 and 14.2 t ha−1, respectively), urea addition significantly increased N2O emission fluxes and banana yields (88.2–177 μg m−2 h−1 and 19.4–25.0 t ha−1, respectively). The stimulation effect of urea on N2O emissions was significantly higher than its effect on banana yield. N2O emission occurred in pulses during banana cultivation due to repeated topdressing. The cumulative N2O emissions and N2O emission factor of urea applied in banana plantations were estimated to be 6.39–12.8 kg N ha−1 and 1.46–2.31 %, respectively. Notably, N2O emissions were significantly positively correlated with urea application rate, temperature, and NH4 + levels, suggesting that temperature and NH4 + availability are the most important factors controlling N2O emissions in tropical banana plantations. Combined NBPT and DCD treatment greatly reduced N2O emissions (by 65.4 %) and increased banana yields (by 4.5 %).