Framework for Land Evaluation (FLE)

The Framework for Land Evaluation (FLE) is a set of principles and concepts, on the basis of which local, national or regional land suitability evaluation systems can be constructed. The land suitability evaluation system is based on the assumption that land can be ranked into distinctly different categories, each one corresponding with a different potential for a particular use. Categories commonly used are: highly suitable (S1), moderately suitable (S2), marginally suitable (S3), unsuitable (N). These categories, a.k.a. suitability classes, can be further subdivided. Suitability is assessed by matching land characteristics or land qualities to the requirements of specified land utilization types. Land characteristics are attributes of land that can be measured or estimated, land qualities are not measurable but are interpreted attributes of land. The FLE advocates a 5-step approach to the land evaluation process. Step 1 involves the classification of land into areas that are as homogeneous as possible to be of practical value at the scale and for the purpose of the land evaluation. Step 2 involves the identification of the land use against which the potential or constraints of land will be evaluated. According to the scale and objectives of the land evaluation exercise, this could be major land use categories, crops, major land improvements. Step 3 involves the identification of climatic, soil and terrain requirements for the specified land utilization type. The requirements are presented in the form of a requirements table, which links ranges and threshold values for relevant land characteristics to suitability ratings for the specified use. Step 4 involves the identification of relevant land limitations that will affect the expected returns from using land in the manner specified by the land utilization type, and the rating of different land units according to these land limitations. Step 5 involves the conversion of the land limitations table into a suitability ranking for each selected land utilization type. It is the basis for comparing the potential of different land use/management options on different tracts of land. The types of land evaluation can be represented along 2 axes: (1) physical versus economical, and (2) qualitative versus quantitative. In physical land evaluation ecological and technological requirements of land use are matched with the physical land qualities or land characteristics. The result is a relative or qualitative ranking of land in the form of physical suitability classes. In economic land evaluation different land use alternatives can be compared by valuating inputs and outputs. Physical and economic land evaluations follow different procedures and have very different data requirements. A qualitative land evaluation is one where the suitability of land for different purposes is outlined in relative terms only. Most physical land evaluations are in that category. In a quantitative land evaluation quantitative estimates of the production or other benefits are provided, e.g. crop yields, timber growth rates, etc. The level of detailed analysis required for quantitative land evaluation in fact makes it the basis for an economic evaluation.