Chemical Properties of Soils in Reforested and Bare Areas in Salt Affected Area of Khon Kaen Province, Thailand

抄録

Salt affected soil is a severe environmental problem in northeast of Thailand. About 16.82 percent of the total land area in the region is accounted for the salt affected area. In the study area of Phra Yun district, Khon Khaen province, there were many studies since 1990 and 18 governmental projects of Thailand have been conducted for rehabilitating salt affected soil since 1999. However, attention has been paid to the current condition of salt accumulation in Phra Yun district, after many studies and projects have been implemented. So in this study, soil survey was conducted in four areas, Eucalyptus (Eucalyptus camaldulensis) reforested area and adjacent bare area, Acacia (Acacia ampliceps) reforested area and adjacent bare area. Disturbed and undisturbed soil samples were collected for analyzing physical and chemical properties of soils. The differences in chemical properties of soils were analyzed by t-test statistical method. The results showed that EC_1:5 values of soils in reforested and adjacent bare areas were significantly different at 99%. The sodium and calcium concentration of soils at the same depth in reforested and adjacent bare areas also showed significant different at 95% and 99%. Moreover, there was a tendency that EC_1:5 values, sodium and calcium concentration decreased with soil depth due to accumulation of salts at the surface layers. Although many studies and projects have been implemented in Phra Yun district, salt accumulation has been still severe, especially in bare areas. In addition, it was clearly observed that reforested areas of Eucalyptus and Acacia tended to be lower in electrical conductivity, sodium and calcium concentration than that of adjacent bare areas. Thus, it was concluded that reforestation is an effective approach to rehabilitate salt affected soil.