Soil Salinization Assessment and Monitoring at Boe Klue District, Nan Province, Northern Thailand

Abstract

Thailand is an agrarian country with a total land area of 51.4 × 106 hectares (ha), of which 38% are farm land, 25% are forests, and the remaining 37% cover urban area, public area, sanitation, swamp land, railroad, highways, real estate, and others. Thailand has been changed in the last five decades due to rapid population increase and land use pattern change. The encroachment of natural forests, use of marginal lands, and mismanagement of soil and water resources have degraded soil and water resources. It is estimated that degraded soils cover 31 × 106 ha or 60% of the total land area of the country, comprising six major soil problems, that is, acid sulfate soils, peat soils, sandy soils, eroded soil, mined soils, and saline soils. Saline soils are the oldest and represent one of the most important environmental problems to humanity. In Thailand, they occupy 3.5 × 106 ha area. These soils reduced the agricultural productivity in the northern region, northeastern region, the Central Plain, and along the coastal areas of the country. It is therefore important to assess and monitor soil salinization in these areas for better management of agricultural soils. This has been accomplished in Boe Klue District, Nan Province, Northern Thailand. The methodologies used are geophysical method, ground-based surveys using EM38 measurement and laboratory analysis of soil and water samples. The result showed the occurrence of salt on soil surface being derived from soil salinization as a natural phenomenon. The source of salts is found to be from strike slip of Boe Klue formation. Salinized soils have been found to coincide with shallow saline groundwater or exposure of Boe Klue formation.