Greenhouse gas emissions from rice crop with different tillage permutations in rice–wheat system

Global agriculture lies in intersection of two inescapable issues of the present times, viz. keeping pace with growing food demand and participating in climate change mitigation efforts. Rice cultivation is a major emitter of greenhouse gases (GHGs) and no tillage of soil is becoming popular due to low economic investments with improved soil conditions. However, how these arrangements will affect GHG emissions need to be quantified. Therefore, monitoring over diverse agricultural practices is essential for optimum utilization of cultivable land and resources, while identifying the chances of emission reductions. We assessed the impacts of four tillage practices in rice–wheat cultivation system on fluxes of GHGs (CH4, N2O and CO2) and yield of rice. The tillage practices were tilling of soil before sowing of every crop (RCT-WCT), tillage before sowing of rice but no tillage before sowing of wheat (RCT-WNT), tillage before sowing of wheat but no tillage before sowing of rice (RNT-WCT), and no tillage before sowing of rice as well as wheat (RNT-WNT). Reduction in tillage frequency led to significant reductions in fluxes of CH4 and N2O, but increased CO2 while permutations of tillage and no tillage influenced grain yield. RNT-WCT produced next to or comparable to the most yielding RCT-WCT. Although it is difficult to select the best performer since no single tillage permutation showed consistent increment in yield with accompanied emission reductions, RNT-WCT, however may be considered as better agricultural practice for the study region. Long term and extensive spatio-temporal monitoring is still required before making any recommendation. It is also essential for understanding the factors that cause declination in yields under no tillage.

► Reduced tillage frequency decreased GHG emissions.
► Yield was reduced under continuous no tillage.
► Tradeoff between CH4 and CO2 was found under all tillage permutations.
► No tillage before sowing rice but tillage before sowing of wheat was better than conventional tillage practice.