Urease inhibitor and biochar independently affected N2 O emissions from Camellia oleifera soils

Abstract

Nitrous oxide (N2 O) is a long-lived greenhouse gas that impacts climate change. Agricultural soils with intensive nitrogen (N) application are the main source of N2 O emissions. Reducing N2 O emissions from N-fertilised soils is, therefore, important for climate change mitigation. The application of urease inhibitor and/or biochar pro-vides the potential for mitigating N2 O emissions. However, the interactive effect of urease inhibitor and biochar on N2 O emissions remains limited. In this study, an incubation experiment was performed to investigate the gradients of urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) (0, 0.08, 0.16, and 0.24%) and biochar additions (0, 2.5, and 5%) on N2 O emissions from urea-fertilised Camellia oleifera soils. Results showed that urease inhibitor decreased, but biochar increased cumulative N2 O emissions. No significant interactive effects were observed between urease inhibitor and biochar on the cumulative N2 O emissions, but cumulative N2 O emissions were decreased by NBPT under a 2.5% biochar addition rate. Soil N2 O emission rates were negatively correlated with net ammo-nification and N mineralisation rates and positively correlated with net nitrification rates. This study indicates that NBPT, with the characteristic of delaying urea hydrolysis, can be better than biochar in mitigating N2 O emissions from urea-fertilised soils of C. oleifera plantations.