Assessing the potential of alternative farming practices for sustainable energy and water use and GHG mitigation in conventional maize systems

Conventional maize systems in Mexico rely heavily on synthetic fertilizers, diesel, and fossil-derived electricity and demand large amounts of irrigation water due to extensive use of low-efficiency furrow irrigation methods. These considerations raise concerns about the sustainability of conventional farming methods for growing maize, a staple crop for Mexican people. The present study evaluates potential energy, greenhouse gas (GHG) emissions, and irrigation water savings in conventional high-input maize systems in Mexico resulting from introducing alternative farming practices. Six different alternative practices related to soil, nutrient, and irrigation management were evaluated using literature data about expected changes in crop input rates and field operations performed. Overall, energy intensity (EI, GJ Mg-1 of grain) varied by - 28% to + 33%, GHG intensity (GHGI, kg-CO(2)e Mg-1 of grain) by - 14% to + 14%, and irrigation water productivity (IWP, kg-grain m(-3) of applied irrigation) by + 12% to + 88% under the different alternative practice scenarios. Partly replacing synthetic N fertilizer with animal manure or legume green manure and improving N fertilizer use efficiency provided the largest potential savings in EI. Improving N fertilizer use efficiency led to the greatest potential reductions in GHGI, while converting to pressurized irrigation methods and switching to reduced tillage caused the major potential increases in IWP due to irrigation water minimization. Results provide a good proxy for the impacts of resource-conserving practices on the energy, GHG, and irrigation water budgets of conventional maize systems and can inform decisions about effective management changes to make maize farming more sustainable.