Historical summary of soil-related activities in Thailand

               Soil survey and classification started in Thailand since before the World War II. Dr. Robert L. Pendleton – an American soil scientist coming to Thailand around the year 1935 as an advisor of the Ministry of Agriculture – was the pioneer in such discipline along with a Thai technician, Dr. Sarot Montrakun (a soil scientist from the Philippines who later naturalized to be a Thai national) as his close colleague. At that time the transportation system in the country was not convenient, so the soil survey could specifically be carried out for only some places. Identification of the boundary of each soil type had to rely on the geology map (surface rocks) and forestry map (types of trees).
               However, there was a publication of the “Provisional Map of Soils and Surface Rocks of the Kingdom of Thailand” by Robert L. Pendleton with a scale of 1:2,500,000, in 1949. There were 21 units of soil types, e.g. Lopburi clays, Khorat fine sandy loan and Chiangmai loam, etc.