Combining results of different models: the case of a levy on the Dutch nitrogen surplus

Economic instruments, such as levies are considered by the Dutch government for reducing the harmful effects of the production and application of manure. To analyse these levies a framework which makes it possible to combine and to choose among different types of research is developed. The results are integrated along the line of the marginal abatement cost curve. The problems related to integrating different types of research are taken into account. The method developed allows every farmer to react to a levy differently. A levy turns out to be more effective to reduce the nitrogen surplus on farm level in the pig fattening sector when compared to the pig breeding sector. But even a levy of 2 guilderd/kg of nitrogen does not remove the total manure surplus in the pig sector and results in large profit losses. Further research is needed to underpin the empirical input required by the model.