Using mitigation and adaptation strategies to optimise crop yield and greenhouse gas emissions

The global agricultural sector accounts for ~14% of the total anthropogenic greenhouse gas (GHG) emissions, of which 46% are generated as N2O emissions from nitrogen fertilizers, 45% is contributed by CH4 from manure and livestock fermentation, and 9% stems from CO2 as a result of soil organic matter decomposition. Several mitigation strategies were proposed, with the aim to reduce GHG emissions. However, these practices are generally not evaluated in combination with adaptation strategies that farmers may implement independently to offset climate change impacts. The biogeochemical model DNDC was used to assess the role of sustainable mitigation and adaptation strategies on the optimization on crop yield and GHG emissions (CO2eq/ha) in an intensively managed agricultural region of Tuscany, Italy, under a predicted warmer and drier climate. The simulated crop was maize (Zea mays L.). The model was used to simulate maize yield using different mitigation strategies (type and amount of soil amendments) and adaptation strategies (sowing dates and maize cultivars). The future climate scenario was created by increasing present (1976-2005) air mean temperature by 2°C and reducing daily rainfall by 10%. Results from the simulation suggested that longer growing season cultivars and earlier sowing dates in association with high N inputs may be adopted as strategies to increase maize yield compared with the standard crop and soil management strategy. Low N inputs with higher residue incorporation may be adopted to mitigate GHG emissions. However, in order to optimize both maize crop yield and GHG emissions only a few strategies were acceptable and included low organic N input with high residue incorporation in conjunction with a longer growing season cultivar and an early sowing date.