Soil carbon sequestration, climate change mitigation, nitrogen pollution and agro-food supply: navigating trade-offs in future cropland management strategies

Abstract

Model-based scenarios are essential for assessing the potential of agricultural management strategies to achieve sustainable development goals. However, to date, knowledge of the trade-offs and synergies between greenhouse gas (GHG) emissions and nitrogen (N) reduction, carbon sequestration, and food provisioning under different agricultural practices remains limited, with most studies focusing on global and national scales. The present study implements the generalized representation of agro-food system model coupled with the soil organic carbon (SOC) AMG model in the Tuojiang River Basin, China, to assess the effects of 24 agricultural scenarios on SOC stock, the GHG budget, nitrogen (N) surplus, and export capacity at the county level in 2035. We considered viable options by modifying four levers: (i) synthetic fertilizer inputs, (ii) livestock population size and the fraction of animal proteins in the human diet, (iii) the share of legumes in crop rotation, and (iv) the proportion of straw used for bioenergy production. We found that the potential of biofuels to substitute fossil fuel emissions remains low across all scenarios, reducing by 2.9%-5.3% of current emissions. Our results also reveal synergies in reducing GHG emissions and N pollution, with reductions of 39%-43% and 26%-52%, respectively, under agro-ecological scenarios with zero N fertilizer application and halving of the livestock population. In contrast, trade-offs were identified between SOC sequestration and export capacity, both of which were lower in agro-ecological scenarios than in the others.