How cost-effective is a mixed policy targeting the management of three pollutants from N-fertilizers

This paper assesses the cost-effectiveness of a mixed policy in attempts to curb three nitrogen pollutants: NO3, N20 and NH3. The policy under study combines an N-tax on nitrogen input and incentives promoting perennial crops assumed to require low input. We show that opting for a perennial crop subsidy, in addition to an N-tax, significantly increases tax effectiveness in the case of N03. A quantitative analysis provides an assessment of impacts in terms of land-use, farmers' income and N losses throughout France and at the river-basin scale.