Nutrient Management Research Database

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 CO₂emissions 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.

• Splitting fertilizer applications has been suggested as a way to reduce fertilization driven N2O emissions.
• Urea was applied at rates equivalent to 180 and 360 lbs N/ac either in a single event or split between 4 application events spaced 16 days apart.
• Each fertilizer treatment was also applied to either soil of varying moisture levels.

• Total N2O emissions were reduced by 28% when urea application was applied across 4 application events.
• The reduction in N2O that resulted from splitting urea application was more pronounced at the lower N levels (45% reduction) than the higher N rate (15% reduction).