Effect of Sedimentary Environment in Iron and Manganese Crystallization Index of some Soil of Anbar Government

Abstract

This study was conducted to elucidate the impact of depositional conditions on different sedimentary and desert environments on the crystallization index of iron and manganese. The study area is located within the administrative boundaries of Anbar Governorate. Eight desert valleys were selected, including Al-Qaim Valley, Al-Mohammadi Valley, Al-Damamah Valley, Hauran Valley, Al-Baghdadi Valley, Zaghdan Valley, Al-Sahliyah Valley, and Al-Sheikh Hadeed Valley, with two pedons per site, one in the sedimentary deposits and one in the desert deposits. The samples were prepared for laboratory analysis. Total iron and manganese, non-crystalline iron and manganese oxides, crystalline iron and manganese oxides. Then, the crystallization index was calculated for both iron and manganese elements in both sedimentary and desert soils alike. The results showed that the values of the soil pH in sedimentary soils ranged from 7.12-8.06, while they were recorded in the desert soils with a range of 7.31-8.03. In general, they fell within the limits of basic to highly basic degrees. Electrical conductivity (Ec) was recorded in a range of 0.76-11.80 ds.m-1, which were classified as low salinity to saline soils, as their values decreased with increasing depth in both desert and sedimentary soils are the result of climatic conditions of high temperatures in as well as water and wind additions that helped the accumulation of salts in the surface horizons. The cation exchangeable capacity (CEC) varied between 10.06 and 40.58 cmolc.kg-1, consistently corresponding to the clay content present in the soil. Notably, desert soils exhibited superior crystallization indices for iron and manganese compared to sedimentary soils. However, there was a decline in the crystallization index of iron relative to manganese across all study soils, attributed to the high content of total iron in the parent material, with the presence of a certain pattern in the distribution in the desert soils, where it took a regular distribution with the depth. On another hand, in the sedimentary soils it took a random distribution with the depth due to influence of the sedimentary soils with the movement and transmission of the separate clay through the soil horizons. The ratio of iron to manganese crystallization varied from 0.140 to 14.142 Generally, it increased with depth in desert and sedimentary soils, except for Hauran valley and Al-Baghdadi valley soils, where it decreased due to high total iron content in their parent material.