Spatialising crop models

There are many incentives for applying a crop model at a regional scale, i.e. over an area larger than that for which it has been developed. This is what we call “spatialising” a crop model. These large areas can have very heterogeneous soil, climate and management practices. Consequently, spatialising a crop model can pose serious problems. One set arises from the fact that the basic concepts, hypotheses and validity domains of crop models are derived at the plot scale and may not apply at a larger scale. Another set arises from the lack of adequate and sufficient data to run the model at a regional scale. The workshop held in Toulouse (France) on 14–15 January 2002 dealt with the topic of spatialising crop models. The present paper is a comprehensive summary of the thoughts we had before, during and after the workshop.