The Nature and Genesis of Some Salt-Affected Soils in Iran
1979
Mahjoory, Ramez A.
Salt-affected soils are distributed throughout arid to semiarid regions of Iran. They occupy about 15% of the area in the country, an amount equal to the total arable land. These soils are formed in level to depressional landform positions under the influence of a fluctuating ground water table. Three pedons representing different soil series were studied: Amir-abad (pedon 1), Farsian (pedon 2) and Ahoo-char (pedon 3). Pedon 1 was classified as a Haploxerollic Natrargid, pedon 2 as an Aquic Natrargid, and pedon 3 as an Aquic Natrargid. The origin of salts is related to the parent materials that formed from saliniferous and gypsiferous marl deposits and carried by water and redeposited. Saturated paste extracts are high in chlorides, sulfates, and carbonates in all three pedons, but increased in amounts from pedon 1 to pedons 2 and 3. ESP and SAR are more than 15 in all three soils studied. The average electrical conductivity (EC) values of pedon 1, 2, and 3 are 13, 16, and 32 mmho/cm, respectively. The pH values vary from 8 – 10. X-ray diffraction and chemical data indicate that the soils contain vermiculite (18–48%), clay mica (18–28%), interstratified vermiculite and/or chlorite-clay mica, kaolinite, and quartz. Montmorillonite and attapulgite were found only in pedon 3.
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