CGMS soil Suitability Criteria
Application of a sequence of decreasingly severe sets of suitability rules
The function of soils in agriculture is to provide a favourable growing environment for the plant roots and a good working environment for the farmer. The plant roots require that the soil provides them space, foothold, water, oxygen, nutrients and absence of toxicity and diseases, the farmer requires that the soil allows mechanization and is easy to till. According to cropping handbooks, the best soils for most arable crops are deep, well drained, medium textured soils in level topography. It could be added that the soil should be not saline, alkaline, rocky, peaty, and stony. In this way, the soils are defined by the presence of favourable properties and the absence of bad properties. It is more practical to define a selection of suitable soils by a set of exclusion criteria, the unsuitability rules.
We have applied very simple single rules, and in a first step to exclude only the soils with extremely unfavourable soil conditions. This leads to a selection of soils from which only the soils of the lowest production potential have been excluded. In a second step, the selection of more or less suitable soils is reduced further by applying additional unsuitability criteria. In each next step of the procedure one criterion is added in order to identify step by step a smaller selection of increasingly better soils. The resulting series of suitability maps are evaluated by comparing them countrywise with the land cover map.
