Yield-scaled N<sub>2</sub>O and CH<sub>4</sub> emissions as affected by combined application of stabilized nitrogen fertilizer and pig manure in rice fields

Abstract

A field experiment was conducted to study the effects of stabilized nitrogen fertilizer combined with pig manure on rice yield and nitrous oxide (N<sub>2</sub>O) and methane (CH<sub>4</sub>) 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 N<sub>2</sub>O emission, but PM + U + I showed no significant difference from PM on N<sub>2</sub>O cumulative emission, indicating that stabilized nitrogen fertilizer combined with PM is effective at reducing N<sub>2</sub>O emissions. The cumulative emission of CH<sub>4</sub> 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 CH<sub>4</sub> 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.