Yield-scaled N2O and CH4 emissions as affected by combined application of stabilized nitrogen fertilizer and pig manure in rice fields

A field experiment was conducted to study the effects of stabilized nitrogen fertilizer combined with pig manure on rice yield and nitrous oxide (N2O) and methane (CH4) emissions. Four treatments were established: urea (U); pig manure (PM); PM and urea (PM + U); PM and stabilized nitrogen fertilizer (urea plus 1% NBPT (N-(n-butyl) thiophosphoric triamide), 1% PPD (phenylphosphorodiamidate) and 2% DMPP (3,4-dimethylpyrazole phosphate)) (PM + U + I). In this study, compared with PM, PM + U significantly increased cumulative N2O emission, but PM + U + I showed no significant difference from PM on N2O cumulative emission, indicating that stabilized nitrogen fertilizer combined with PM is effective at reducing N2O emissions. The cumulative emission of CH4 from PM + U + I treatment was significantly lower than that from PM and PM + U, indicating that stabilized nitrogen fertilizer combined with PM can effectively reduce CH4 emissions as well. The yields of PM + U and PM + U + I were not significantly different from those of U and PM, indicating that local conventional nitrogen application and returns of PM can provide sufficient nitrogen for rice growth. For yield-scaled emissions (YSE), PM was the highest, while PM + U + I significantly decreased YSE. Concomitant application of stabilized nitrogen fertilizer can achieve the goal of reducing YSE when PM is returned to the field.