Feasibility of national nitrogen balances

For some years, the EU has developed policy aiming to reduce environmental pollution due to nitrogen. Today there are no really satisfying means to assess the impacts of this policy. A "farm gate like" kind of balance applied at a national level could be used as an indicator. Farm gate balances are calculated using inputs and outputs of farms. Knowing the amount of nitrogen contained by each product arriving or leaving the farm, one is able to calculate the variations in the stock of nitrogen. The model discussed uses data from international trade to determine the balance of nitrogen exchanges for a country during a year. Some countries have already created such balances, nevertheless, this model brings a major improvement in the fact that the data used are available in the same format and easy to obtain for each country of the EU. Of course, some extra inputs have to be taken into account (fishing, nitrogen transport by rivers, etc.) to obtain a whole balance. The main problems in the completion of the study are the classification of the international trade data and the availability of nitrogen content coefficients. Hence, only partial results are presented. The products found in the international trade classification with N content have been divided among several compartments (feedstuff, manufactured products, etc.) and categories. The categories were made to assess the flows of nitrogen attributable to agricultural activities. The results show that most of the EU Member States import more nitrogen than they export although fertilizer and other importations are not taken into account. For many countries, one of the main entrances of the system is food. Even if the data are not completed for the whole model yet, the partial results are interesting. They demonstrate the usefulness this kind of balance could have in assessing the effects of european policies and, moreover, the weight it could have in negotiating international economic agreements.