External Effects of Agricultural Production in Italy and Environmental Accounting

This paper deals with the valuation of some negative external effects arising from agricultural production in Italy. External effects are treated in a transformation function as a 'bad' output additional to the normal output of a production activity. In this case we can distinguish a price component or shadow price of the external effect and a quantity component and estimate them separately. In order to calculate the price component of the external effects we first estimate one point on the marginal external costs curve and then try to obtain the whole curve, i.e. external costs associated to different levels of emissions in different years. As to the quantity component, net emissions of Nitrogen, Phosphorus and Potassium have been estimated. The aggregate value of external effects is then calculated for thirty years from 1961 to 1991 and deducted from the value added of the agricultural sector, as a first step towards the correction of national accounting aggregates to take environmental degradation into account.