Soil mapping for land-use planning in a karst area of N Thailand with due consideration of local knowledge

Soil maps provide critical knowledge for sustainable land management. However, data collection is laborious and time-consuming, and conventional soil maps are not always relevant. Some authors suggest that farmers can provide valuable soil knowledge. This article presents a study which compares scientific and local soil knowledge in north Thailand. First, the researchers used scientific methods to compile a petrographic map of the region, which characterizes soils based on rock classifications. Then, to gather local knowledge, they conducted interviews and facilitated participatory mapping with local farmers. Color became the primary criterion by which farmers classified soils. This system is specific enough for farmers to be able to relate a range of soil properties to each classification. Their identification of soil fertility based on these color classifications was verified by laboratory analyses. The local soil map was similar to the petrographic map; however, it was strongly dissimilar to the World Reference Base (WRB) map, which bases its classification on diagnostic characteristics. Although local soil maps cannot replace conventional mapping, this study indicates that participatory soil mapping can serve as an efficient way to gather information.