Investigating Carbonate Distribution in Particle Size Components of Some Soils of Khuzestan Province

Characteristics of most soils in arid and semi-arid regions affected by carbonates. The study aimed to determine the distribution of carbonates in the size components of some soils in Khuzestan province. Upward to the bottom of Karun, Karkheh, and Jarahi rivers were studied at depths of 0-50, 50-100, and 150-100 cm. The results showed that the average amount of carbonates in the soils of the Jarahi river basin (37%) was significantly different from the amount in the soils of the other two rivers (33%). Carbonates were observed in all soil size components but the maximum was present in the clay component. The highest regression relationship between soil particles was in the clay component (0.375). The highest percentage of particle reduction after carbonate removal was related to coarse silt particles (0.75). Therefore, the soil texture changed from clay in Jarahi, from clay and silty clay in Karun, and silty clay in Karkheh due to the removal of carbonates to sandy loam. There was no significant difference in the distribution of carbonates at different depths for river soils and all studied soils. The relatively uniform distribution of carbonates in the four components studied in these soils from the surface to the depth showed that the carbonates originated from the parent material, namely alluvial flood sediments of these rivers.