To address the environmental impacts of agricultural production, economic models have to better take into account the relationship between inputs (fertiliser, animal feeding), outputs and the environment. We present an integrated approach which introduces yield response functions to nitrogen in our economic model AROPAj. The farm-type approach for each EU region, relying on an agro-pedo-climatic database, and the linking of a crop model (STICS) to an economic model are an innovation. The methodology was applied to two French regions and focuses here on GHG emissions. The results showed that variables were more sensitive to crop price variation.