Rice production, nitrous oxide emission and ammonia volatilization as impacted by the nitrification inhibitor 2-chloro-6-(trichloromethyl)-pyridine

Abstract

The effectiveness of nitrification inhibitor use in rice paddy fields is variable. In this regard, the impact of 2-chloro-6-(trichloromethyl)-pyridine (CP) nitrification inhibitor on rice yields and nitrogen (N) losses via nitrous oxide (N2O) emission and ammonia (NH3) volatilization from rice paddy fields was studied using five treatments: CK (no N applied), N180 and N240 (180kgNha−1 and 240kgNha−1 applied) and their counterparts N180+CP and N240+CP (N use plus CP). The field experiment was conducted in a major rice cultivation region of China in 2012 and 2013. The results showed that N180+CP increased rice yield by 10% in 2012 and 17% in 2013 compared with N180, and reached the same yield as N240. The N2O losses were 0.88% of N applied in 2012 and 0.38% in 2013 for N180, while they were reduced to 0.44% and 0.19% for N180+CP in the two years, respectively. For N240, CP decreased N2O losses from 0.78% to 0.71% in 2012 and from 0.38% to 0.22% in 2013. However, NH3 volatilization was increased by CP from 7.6% of applied N in N180 to 10.2% in N180+CP in 2012 and from 8.5% to 13.0% in 2013. The NH3 volatilization for N240 was increased by CP from 14.3% to 24.3% in 2012 and from 26.6% to 35.3% in 2013. Our results suggested that the decrease in N application was permitted by the use of CP since the same yield with 180kgNha−1 with CP was obtained as with 240kgNha−1 in the absence of CP and decreased direct emission of N2O. Despite the increase in NH3 volatilization with CP, and the consequent increase in indirect N2O emissions, we calculated that CP led to an overall decrease in global warming potential.