Ability of split urea applications to reduce nitrous oxide emissions: A laboratory incubation experiment

• Split urea application (SP) reduced N2O emissions.
• SP reduced CO2 emissions.
• Soil moisture conditions affect the ability of SP to reduce N2O emissions.
• Fertilizer rate affect the ability of SP to reduce N2O emissions.

Although split fertilizer applications have been suggested as a logical strategy to reduce nitrous oxide (N2O) emissions by decreasing soil nitrate concentrations, their efficacy remains unclear. A laboratory incubation experiment was performed to determine the effect of split fertilization vs. single fertilization on N2O emissions. The split urea application reduced the peak N2O emissions during the incubation period, and the cumulative N2O emissions were significantly reduced by 28% compared with the single fertilization, although these emissions were influenced by the N fertilizer rate and soil moisture. A higher percentage reduction in cumulative N2O emissions under the split fertilization occurred at the low (45%) compared with the high fertilizer rate (15%). At the low fertilizer rate (200 N), the split fertilization resulted in a significantly greater reduction in N2O emissions under the dry soil moisture regime (53%) compared with the wet soil moisture condition (37%). In addition, the split fertilization reduced the cumulative CO2 emissions by 9% compared with the single fertilization. Therefore, our laboratory results suggest that the split fertilization strategy appears to be a useful method to reduce greenhouse gas emissions in an irrigated agriculture ecosystem.