Determining the economic gains from regulation at the extensive and intensive margins

Among the second-best approaches for the regulation of pollution,little attention has been paid to the distorting effect of intensivemargin policies on the extensive margin. This article shows,within a dynamic framework, that regulation of the intensivemargin has to be complemented by regulation of the extensivemargin. Depending on the elasticity of the pollution functionwith respect to nitrogen use, the appropriate regulation atthe extensive margin is zero, a tax or a subsidy. We show empiricallythat combining a nitrogen tax with land-use taxes is about 18per cent more cost efficient than a nitrogen tax alone and 58per cent more efficient than off-site abatement in the formof groundwater treatment.