Northeast region of Thailand covers an area of about 170,000 sq.km. and contains approximately 21 millions
population or 1/3 of the kingdom both area and population. Over 70% of the population is engaged in rainfed
agriculture. The major constraints of agriculture include insufficient water, infertile soil and salinity. Soil
salinization is a crucial problem and increasingly widespread especially in the Northeast where the extensive areas
are underlain by rock salts (Department of Mineral Resource, 1982). The close examination of salt crusts confirmed
that the rock salt of the Maha Sarakham Formation is the source of salt (Sinanuwong et al., 1974; Phianchareon,
1973; Thai-Australia Tung Kula Ronghai (TKR) project, 1983)