Nitrification and Denitrification Associated with N 2 O Production in a Temperate N‐Fertilized Irrigated Uruguayan Rice Field

Uruguay is the seventh largest rice exporting country in the world. Nitrogen is the single most limiting factor for rice production. Microbial soil processes, e.g. nitrification, denitrification and mineralization, influence the fate of the “mobile” N atom. There are gaps in the understanding of key processes that govern N cycling, availability and plant acquisition in irrigated rice systems. Nitrous oxide (N2O), a greenhouse gas, is produced as a by-product during nitrification and occurs as an intermediate during denitrification. The use of fertilizers with inhibitors of nitrification has been proposed as a mitigation strategy. This study showed that less than 7% of the total N2O emission from ENTEC®-fertilized soils, containing an inhibitor of nitrification (DMPP: 3.4-dimethylpyrazolephosphate) was due to nitrification. T-RFLP amoA analysis detected the presence of Nitrosomonas and Nitrosospira genera in urea-fertilized plots.