Efficacité et limites d'une taxe sur les engrais azotés : éléments d'analyse à partir de seize pays européens

In Europe, despite the mixed results obtained, it is administrative regulations that are predominantly used to control nonpoint source nitrogen pollution. The application of other instruments, such as a tax on nitrogen fertilisers, is considered to be more effective but is controversial among economists, who disagree on the price-elasticity of demand for fertilisers and hence on the decline in volume to be expected. Such a tax has already been implemented in four European countries and it seems useful to analyse its effects by comparison with the other countries. With this in mind, after a presentation of the existing taxation experiences, the paper first provides a descriptive statistical analysis, before applying an econometric approach to determine the main factors able to explain the consumption of nitrogen fertilisers. The results show: i) the absence of any structural effect of taxation, ii) the very weak influence of the price of nitrogen fertilisers on the evolution of their consumption, relative to the influence of the prices of pesticides and of agricultural products, iii) the significant role played by the growth of yields over time, and iv) the influence of the share of ploughed area versus grassland, these two latter elements forming part of the general process of intensification in farming. This process is itself consistent with agricultural pricing policy over the period.