Impermeable layers in salt affected sandy soils in Northeast Thailand (Part 1)
1992
Nayana Puengpan | Terdsak Subhasaram | Pongsiri Patcharapreecha | Miura, Kenzo | Wada, Hidenori (Khon Kaen Univ., Khon Kaen (Thailand). Faculty of Science. Dept. of Chemistry)
Detailed observations in the salt affected sandy areas revealed that one of the unknown factors which control movement of water and salt and growth of weeds was the presence near the soil surface of rather thin impermeable layers which were rich in clay and organic matter. In the rainy season, weeds were absent and salt crust was quickly formed after termination of rain at patches where the impermeable layers were exposed to or located near the soil surface. This was considered to be caused by the fact that salt content was high and reductive state was developed in these impermeable layers. Salt crust was formed by being supplied with salt from the impermeable layers and weeds were obliged to be tolerant to both salt and reductive state. This consideration was supported by field tests. Consequently, the impermeable layers were considered as the secondary source of salt, the primary source of salt being the salty groundwater.
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