Local soil classification and comparison of indigenous and technical soil maps in a Mesoamerican community using spatial analysis

The soil classification system developed by a Purhépecha community in central Mexico was formalized, incorporating symbolic, cognitive and practical components. The soil is recognized by farmers as a three-dimensional living body, composed of earth material, air and fluids, organic matter, and living organisms including plants and animals, and organized in layers. The indigenous soil taxonomy is hierarchical, with four categorical levels, and soil classification is flexible enough to adapt to a changing social and environmental context. The local soil map units were compared to those provided by a technical soil classification of general scope (USDA soil taxonomy), using spatial analysis within a GIS environment to determine levels of cartographic correlation. The average spatial correlation at high taxonomic level, computed taking into account only the dominant soils in each map unit, is 74% for the technical–local comparison and 75% for local–technical comparison. At low taxonomic level, the average spatial correlation based on dominant soils only is 62% for the technical–local comparison and 61% for the local–technical comparison. The variable levels of spatial correlation between technical and local soil map units reflect differences in the ways both systems classify soils. However, similarities and discrepancies between making technical and local soil maps reveal complementarities. Critical is the evaluation of topsoil characteristics, as the understanding and monitoring of topsoil dynamics are fundamental for land use decision-making by farmers. Spatial correlation analysis of topsoil properties provides a good basis for collaboration between farmers and soil surveyors. Merging technical and local thinking is indispensable to formulate sustainable land management schemes.