The work presented in this thesis had two purposes : to identify the key determinants to regulate the nitrogen pollution, and to test the ability of appliedmodels to assess the impacts of the regulation policies. We first define a framework for understanding the role of land-use in the optimal management ofnitrogen pollution. Regulation design based on an input taxation coupled to a subsidy for perennial crops seems appropriate. This policy is then evaluatedand we show that it could be cost-effective in the case of nitrate pollution. We also developed the study of aquifer pollution from nitrates. This pollutionproblem leads to develop taking into account of the high inertia of the physical environment considered in reason of the delay between the application offertilizer and pollution of the aquifer. This delay has a significant impact on optimal policy. Besides the pollution stock optimal long-term increases overtime, a path of stronger tax is necessary to achieve the steady-state. The marginal damage value is then estimated for an aquifer associated to the Seineriver basin.