Excess of reactive nitrogen threatens our ecosystems by altering soil, air, water quality and biodiversity. Nitrogen pollution remains a major concern, even greater than carbon, because of its complex effects on ecosystems. Especially, nitrogen losses to water streams are of great concern for territories that are specialized in livestock farming. In the near future, it is expected that such losses will increase under extreme events as a consequence of climate change. According to the “safety net hypothesis”, tree-crop association in livestock areas should prevent nitrogen losses while providing other ecosystem services and supporting agroecosystem productivity. However, the integration of agroforestry with livestock production is limited in temperate regions, and there is an urgent need to provide an assessment of its potential benefits. Started in late 2021, this study aims to explore the potential benefits of agroforestry systems to improve the nitrogen cycle regulation within dairy farming systems in Northwestern France. We hypothesize that the presence of trees or hedgerows impacts the microbial nitrification and favor water drainage within plots, thus limiting nitrogen losses to the environment. We will present the results of a laboratory experiment devoted to the estimation of nitrification stability, i.e. resistance and resilience of nitrifying microbial communities, under different rainfall regimes expected to occur in the near future in this region. Soil samples will be collected from plots designed with alley cropping agroforestry or hedgerow agroforestry. The results will be analyzed using structural equation modelling in order to understand the impact of trees on nitrification stability. Later on, these results will be integrated at the farm’s scale and the territory’s scale using a participative approach in order to balance nitrogen cycle regulation with other ecosystems services.