| |
|---|---|
 (507KB)
|
40,246,000 Yen (FY1998 ; 9,678,000 Yen)
The relationship between salts accumulation and the characteristics of salt affected soils was investigated in both old (Meshet and Sartabn) and new (Yeltai) irrigation blocks within the kolkhoz along the Syrdariya river in Kazakstan. The old sites were abandoned and out of cultivation due to excess salt load, while the new site was being used for the cultivation of various grain and forage crops in rotation. Salt accumulation was dominated by sodium salts, notably sodium chloride and sodium sulphate. The amount of accumulated salt in the top soil of the Yeltai block was lowest in the irrigated blocks within the Kolhoz, and there was no remarkable salt accumulation on the surface. The values of ECe in the top soil of abandoned and cultivated fields were about 20 and 10dS/m respectively. However, the ECe of cultivated fields largely exceeded the criterion for salt affected soils (ECe>4dS/m). Moreover, there was a tendency for higher underground water level due to rice cultivation in the block and the lower layer also contained a lot of salts. The accumulation of salt was affected by the texture of the lower soil horizon such that the accumulation was relatively less when the underlying horizon was sandy, and more when it was clayey. The clay mineral composition of the soils was dominated by the 2:1 layer silicate clays, notably smectite. The nature of the composition was such that might impair the permeability of soluble salts within the soil. Sodium concentration in irrigation water was doubled by salt addition from water entering the irrigation system from the nearby river The drinking water in the area surrounding the irrigation project was very high in SAR and pH, and this posses serious health risks for the local population especially children.
Salt affected soil, Salt accumulation. Irrigation, Water quality, Central Asia.