Studies on saline soils in Khon Kaen region, Northeast Thailand

Abstract

The dynamics of salt movement and the seasonal changes of the physical and chemical properties, especially pH and clay dispersion, of the saline soils in the Khon Kaen Region, Northeast Thailand, were investigated to obtain basic information for the improvement of saline soils. The results obtained are as follows.Not only the salt but also the clay moved upward with the capillary movement of the soil solution, and downward with the percolation of rain water. The soil pH was very low (less than 4) in the dry season and very high (nearly 9) in the rainy season, based on the following reactions: H-clay+NaC1 -*Na-clay + HCI (dry season); Na-clay § H~0-*H-clay § Na0H (rainy season).The soil contained large amounts of dispersible clay in the rainy season, but a small amount in the early dry season. FeS dissolved in the groundwater was considered to be another acidification agent, as it became oxidized to ferric hydroxide (precipitation) and sulfuric acid when it reached the soil surface by capillary movement.Key Words: acidification, alkalinization, clay dispersion, saline soil.The saline soils in the Khon Kaen Region are well weathered sandy textured soils (SL-LS) with a low CEC, low buffering capacity and low organic matter content, and are characterized by the presence of NaC1 as the dominant soluble salt (Patcharapreecha et al. 1989). The climate of this region is clearly differentiated into rainy and dry seasons. Salt moves downward with rainfall during the rainy season while the salt dissolved in the groundwater moves upward and accumulates on the soil surface during the dry season. The concomitant upward and downward movement of clay was also suggested in the model experiment (Patcharapreecha et al. 1987(Patcharapreecha et al. , 1989.In this report, the dynamics of salt movement and the seasonal changes of physical and chemical properties, especially pH and clay dispersion, of the saline soils in the Khon Kaen Region were investigated to obtain basic information for the improvement of saline soils. In addition, the mechanisms of seasonal changes were also studied by leaching experiments.

Monitoring Spatio-Temporal Changes in Vegetation Cover, Soil Salinity and Waterlogging in Siwa Oasis, Egypt Using Remote Sensing Data and Techniques رصد التغیرات المکانیة والزمانیة فی الغطاء النباتی وملوحة التربة والغدق بالمیاه فی واحة سیوة ، مصر باستخدام بیانات وتقنیات الاستشعار عن بعد

“…It is either human-induced or naturally occurred. It causes negative impacts on plant growth and sustainability of agricultural lands (Ghassemi et al, 1995;Hanson et al, 1999;Toparkngarm, 2006). Consequently, it is imperative to monitor and map soilsalinity at a beginning phase so as to build up a successful soil reclamation plan that could help in the remediation of currently salt-affected soils and preventing future increase in soil salinity.…”