Environmental and economic modelling of organic, stockless, horticultural crop rotations.

Selected results from the ongoing "EU- Rotate_N" research project are presented. This EU 5 th -framework project is developing a model-based decision support system to optimise nitrogen use in horticultural crop rotations across Europe. This paper introduces the economic and the fertility-building crops sub-models, and shows data from model valida- tion and first model runs on an organic farm in central England. Preliminary results show that the model has the potential to be a powerful support tool for farmers and advisors, making decisions on rotational plan- ning. The economic, agronomic and environmental consequences of different rotational designs can be projected and assessed in detail.