Agroecological transitions reveal trade-offs and synergies among ecosystem services

The management of agroecosystems not only shapes the ecosystem services they provide - e.g., food production and soil carbon (C) sequestration - but also determines the environmental impacts they generate - e.g., nitrate leaching and greenhouse gas (GHG) emissions. Here, using soil-crop simulations from the validated STICS model, we compare eight crop rotations over 541,800 ha in southern Belgium. Starting from a conventional and intensive crop rotation, we examined the impacts of progressively adopting various agroecological levers in crop rotations. They range from efficiency improvements - reducing nitrogen (N) fertilization, to agroecosystems redesign - increasing crop diversity and integrating pastures and livestock under different modalities. Results show that reduced N fertilization lowers GHG emissions and nitrate leaching, but also reduces productivity and hence soil organic carbon. Deeper agroecosystem transformations - crop diversification and, to a further extent, integrated crop-livestock systems (ICLS) - further amplify the reductions of GHG emissions and nitrate leaching, while also enhancing SOC and increasing the stability of the productivity. While the primary environmental benefits of crop diversification stem from reduced N fertilizer use, ICLS are crucial for overcoming the traditional trade-off between C storage and N supply. However, the advantages of ICLS largely depend on how pastures are managed regarding to grazing or mowing practices. Our study measures over large spatio-temporal scales the trade-offs between maximizing productivity and minimizing environmental impacts. By quantifying the environmental benefits and economic losses of gradually adopting these agroecological practices, it shows that broader adoption would require financial support for farmers and/or internalizing the environmental costs of agroecosystems.