The research is oriented to agricultural farms with arable land only, and to decisions where already knowledge about that decision is available (crop rotation, kind of fertilizer use, kind of varieties,...). Research will be focussed on the depen- dencies of all these components, on the priorities on which the decisions need to be based on a procedure to optimize the decision. For the loamy soil region of Belgium land- and farm date will be registered. Fields and farms with conparable environment factors and conparable structures, will be aggregated into 'isofarms' and 'isolands'. After two years the research will be enlarged to vegetables and other soil types than loamy soils.