QUANTIFIED EVALUATION OF AGRICULTURAL SOIL CAPABILITY AT THE LOCAL SCALE - A GIS-ASSISTED CASE-STUDY FROM ONTARIO, CANADA

Rural agricultural areas in southern Ontario, Canada, with potential f or aggregate extraction have become a focus of conflict over proposed land use change. Geophysical and soil physical field measurements were used to map soil variation for quantitative land evaluation at the fa rm level. Apparent electrical conductivity of terrain was shown to be strongly correlated with depth to the groundwater table on two separat e test sites. A digital terrain model was used to create thematic maps of the predicted pre-growing season soil water regime by contouring i rregularly spaced electromagnetic survey and soil inspection points. O verlay analysis with a geographical information system (GIS) was used to produce an agricultural soil capability map for crop production. Ad option of a larger map scale provided significant refinement in detail over the published Canada Land Inventory soil capability ratings for agriculture, but both showed that Class 2 soils are dominant. The appr oach can improve the reproducibility of land capability assessments.