Nitrous oxide emission in response to N application in irrigated sugarcane

ABSTRACT The objective of this study was to compare the emissions of nitrous oxide (N2O) resulting from the application of nitrogen (N) and potassium (K) doses in fertigated sugarcane, in comparison to emissions from conventional fertilizer application. The study was conducted in the experimental area of Embrapa Mid-North, Teresina, Piauí state, Brazil, from August 2014 to January 2015. The experimental design was in randomized blocks, analyzed in a (2 x 2) +1 factorial scheme, with four replicates. The treatments consisted of the combination of two doses of N and K2O (60-120 and 120-180 kg ha-1, respectively) and two methods of application (in soil and fertigation), and a control. The use of fertigation reduced the emissions of N2O in sugarcane compared with the crop under conventional fertilization. Increase in N dose from 60 to 120 kg ha-1 applied through fertigation did not affect N2O emissions, while 60 and 120 kg ha-1 applied in the soil led to 40.6 and 50.2% increases in N2O emissions, respectively. The application of 60 and 120 kg ha-1 of N in the soil led to higher N2O emission factor, being 1.39 and 2.08% higher than in the crop fertigated with 60 and 120 kg ha-1 of N, respectively.