1 Plant Archives Vol. 21, Supplement 1, 2021 pp. 1338-1344 e-ISSN:2581-6063 (online), ISSN:0972-5210 Plant Archives Journal homepage: http://www.plantarchives.org doi link : https://doi.org/10.51470/PLANTARCHIVES.2021.v21.S1.2010 IDENTIFICATION AND COMPARISON OF CLAY MINERALS IN SOME GYPSIFEROUS SOILS IN NAJAF AND SALAH AL-DIN GOVERNORATES Basim Sh. Obaid AL-Obaidi, Mahmood A. Lateef* and Jassam S. Jasim Department. of Soil & water Science., College of Agriculture., University. of Tikrit, Iraq *Email: mhoo_1979@yahoo.com ABSTRACT This study was conducted to identify clay minerals in the soils of the sedimentary plain and compare their composition and minerals content to the clays of gypsiferous soils located within the sediments of the Tigris and Euphrates, as six pedons were chosen distributed by three to the sediments of the Tigris River (Salah al-Din) and three others within The sediments of the Euphrates River (Najaf) revealed the pedons and described their morphologically and obtained soil samples from the surface and subsurface horizon for the purpose of conducting mineral analysis on them using the reflection method of X-rays, where the results showed the following: The heterogeneity of the mineral arrangement of the clays in the horizons diagnosed for the pedons of the study soil, with the exception pedon 5 uncultivated. The dominance Palygorskite in all the studied horizons except for the surface horizons pedon 1 and 2,site of Salah al-Din, as the dominance of chlorite and smectite respectively, as well as the pedon 6, site of Najaf, where chlorite occupied the first place. Increase in the percentage of palygorskite in the subsurface horizons In return, it was accompany him by decrease in the proportion of smectite for those horizons and for both sites. Increasing the relative abundance of Illite in the horizons of Najaf compared to Salah al-Din. The pedons exploiting the Tigris and Euphrates deposits showed a marked increase in the ratio of expanded minerals 2:1 (smectite) compared to the untapped pedons. Similarity mineral composition of the sediments of the Tigris and Euphrates, with the relative content of the two between them different. Keywords : Gypsiferous soils, Najaf , Salah al-Din, clay minerals. Introduction It has long been known that clay minerals strongly influence the main physical and chemicals properties of soils, and thus, questions regarding the origin, distribution and composition of these minerals have occupied a prominent place in soil research. (Owliaie et al., 2006; Wilson, 1999). Abbaslou and Abtahi (2007) observed during their study of the origin and distribution of clay minerals in the soils of southern Iran that the mineral composition in them is of the type of palygorskite, chlorite, Illite, and smectite with absence of kaolinite and vermiculite due to unfavorable and unstable conditions for their formation. That the abundance of these two minerals in the soil is largely related to their presence in the parent rocks, chlorite is inherited in the studied soil, and Illite in the soil arises from rock fragmentation (mechanical weathering), while Khademi and Mermut (1998) indicated that these minerals serve as a precursor to pedogenic formation. For other clay minerals in arid and semi-arid regions. Hasan (1981) studied the mineral composition of soils in the Gezira region found the predominance of the minerals of Illite, palygorskite, and kaolinite in the clay part and the soils that were all studied except for one of them, where was the dominion for chlorite, also noted the presence of palygorskite in all studied horizons. Hashemi, (2013) showed when studying the relationship between clay minerals and different soil moisture regimes in gypsiferous soils of Fars Province in southern Iran represented by arid and semi-arid climate that parent material and climatic conditions the most important factor affecting clay minerals distribution,Through which ithas been determining Palygorskite, smectite, chlorite, illite, and kaolinite were identified as the main clay minerals in gypsiferous soils are inherited from parent material and their contents in the different moisture regimesare almost constant,Therefore the present study aims to identify clay minerals in the soils of the study area, and then comparison of the mineral composition of clay in gypsiferous soils of the Tigris and Euphrates precipitations. Materials and Methods Preliminary and field proceedings Field surveys were execution in order to determine the pedons representing for selected locations according on method (Free soil survey) As stated in the US Soil Survey manual Division (1993), The different sites for gypsiferous soil were selected depending on the physiographic location, The nature of sedimentation of the Tigris and Euphrates rivers, The nature of agricultural exploitation, The nature of soil management, The relative content of gypsum in the surface horizons distributed by six pedons, consideration the distance of more than 500 meters from the paved roads, and the pedons locations were determined using a GPS device table (1).