Land units, land utilization types and land use systems need to be defined differently for different scale levels, eg, for farm, regional and world levels, as illustrated in this paper. The Hoosbeek and Bryant diagram, showing methodology as a funciton of spatial scales, is used to illustrate research procedures based on user demands. Land use decisions are made on strategic, tactical and operational levels. On the farm level, point observations are made that are interpolated to areas of land to be used for precision agriculture. Taxonomic land units and static utilization types are irrelevant, the latter because management has to be proactive and dynamic. On the regional level, the traditional concepts of land evaluation fit best but modern application requires quantitative approaches in which different land use options and their trade-offs are compared using linear programming techniques. Finally, the world level involves gross simplifications, where agronomists use an abstract approach with grain equivalents to define production for large grids. Soil science has not as yet developed a satisfactory procedure to define representative soil parameters for each grid. Even though lack of data limits the work in developing countries at this time, we believe that access to information technology and modern techniques such as remote sensing will allow the future use of identical procedures all over the world for each of the different scale levels.
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