Emission estimation of nitrous oxide (N2O) from a wheat cropping system under varying tillage practices and different levels of nitrogen fertiliser

Nitrous oxide is a greenhouse gas with high global warming potential emitted from agricultural sources. The effects of tillage practices and different levels of N fertiliser on seasonal fluxes of N2O were investigated in a field planted with the wheat variety Sonalika. The experiment was conducted during 2012–13 and 2013–14 under conventional tillage (CT) and reduced tillage (RT) farming systems in combination with four different levels of nitrogen fertiliser (i.e. zero nitrogen (F1), 60kgNha–1 (F2), 80kgNha–1 (F3) and 100kgNha–1 (F4)). Both tillage practices and fertiliser significantly (P<0.01) affected seasonal cumulative N2O emissions and wheat yield. However, there was no significant difference in N2O emissions between RTF1 and CTF1 (zero nitrogen). Compared with RT, N2O emission decreased under the CT practice by 2.49%, 10.11%, 7.9% and 27.46% in CTF1, CTF2, CTF3 and CTF4 respectively. Highest and lowest seasonal cumulative fluxes were recorded in RTF4 (N 100kgha–1) and CTF1 (N 0kgha–1) respectively. During the wheat-growing period, nitrogen use efficiency decreased with increasing nitrogen levels and treatment with 60 kg-Nha–1 in the CT practice (CTF2) was found to be effective in increasing nitrogen use efficiency and decreasing yield-scaled N2O emissions.