Effects of nitrogen application rate and a nitrification inhibitor dicyandiamide on ammonia oxidizers and N2O emissions in a grazed pasture soil

Abstract

Ammonia oxidizers, including ammonia oxidizing bacteria (AOB) and ammonia oxidizing archaea (AOA) are important drivers of a key step of the nitrogen cycle - nitrification, which affects the production of the potent greenhouse gas, nitrous oxide (N2O). A field experiment was conducted to determine the effect of nitrogen application rates and the nitrification inhibitor dicyandiamide (DCD) on the abundance of AOB and AOA and on N2O emissions in a grazed pasture soil. Nitrogen (N) was applied at four different rates, with urea applied at 50 and 100kgNha-1 and animal urine at 300 and 600kgNha-1. DCD was applied to some of the N treatments at 10kgha-1. The results showed that the AOB amoA gene c..