No-Till Farming Systems to Reduce Nitrous Oxide Emissions and Increase Methane Uptake

Agricultural activities represent a significant fraction of global greenhouse gas (GHG) emissions to the atmosphere, with a preponderant impact on nitrous oxide (N2O) and methane (CH4) fluxes. The production of these gases in the soil is controlled by different soil characteristics (O2 availability, mineral N content, temperature, pH, organic carbon, and redox potential), which are regulated by climatic conditions and agricultural management practices. In turn, soil physical properties regulate the transport and diffusion of these gases up to the soil surface before they are emitted to the atmosphere. No-tillage (NT) farming, being key for the enhancement of several ecosystem services, can also present benefits in terms of GHG mitigation if combined with best management practices adapted to the specific conditions of NT soils. No-till needs to be managed to maintain adequate soil structural conditions to keep a suitable level of soil aeration, thus reducing the potential for denitrification and methanogenesis. Other management practices such as nitrogen fertilization and irrigation must be oriented towards an efficient use of water and nitrogen, avoiding excesses that lead to high GHG losses. The potential of biological nitrogen fixation must be maximized by adding value to the introduction of legumes into crop sequences.