| Research Abstract |
The purpose of the study was to investigate the mechanism of salt accumulation in the soils with high groundwater levels under arid conditions. The factors brought in the study were physico-chemical characteristics of the soil, groundwater level, and growing plants on the soil. The soils used were the Dune soil, Masa soil, improved Alluvial soil and Red and Yellow soil. The plants used were soybean, cabbage and corn. Several groundwater levels between 15cm and 35cm were kept using mariots.
In the Dune soil, the groundwater level strongly influenced the soil water profile and evapotranspiration. The 30cm level made the surface soil layr dried. The high groundwater levels increased the evapotranspiration, but did not accumulated the salts in the surface soil layr. Neither an increased water consumption by growing plants brought about the salt accumulation. It seemed that the salts moved with water were not fixed due to the low CEC of the Dune soil. This might be supported by the fact that the salt accumulation in the surface soil layr increased with the increasing clay content and CEC of the soil.
In the Red and Yellow soil, the groundwater levels and growing plants had a little effect on soil water profile, but had a large effect on the salt accumulation in the surface soil layr, especially under growing crops. Also the movement and distribution of Na^+ in the groundwater was influenced by the exchanging rate with cations in the soil.
The salt accumulation in the Masa soil and the Alluvial soil was in the middle between the Dune soil and the Red and Yellow soil.
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