GENESIS AND THE DEGREE OF DEVELOPMENT OF THE CLAY AND CALCAREOUS HORIZONS OF SOME SOILS IN NORTHERN IRAQ.

The study was conducted in two selected sites representing some of the soils of Kirkuk and Erbil, northern Iraq, with a total of six pedons. Prospects are revealed and diagnosed morphologically. Samples from each horizon of each pedon were obtained from the soil of the study sites in order to carry out some laboratory tests for physical and chemical properties. In addition to that, unexcited soil samples were taken from the surface and subsurface diagnostic horizons to study the precise morphological characteristics. The results of examining the micro-morphological characteristics of the study sites' soil pedons confirmed the existence of pedogenic evolution, through the presence of some micro morphological features, including Argillans and Calcitans, as well as the presence of coating films on the outer surfaces of the interfacial gaps. The results also showed the presence of discontinuous mud films that are not integrated as for the dominant structure in most of the study soils pedons. It is the complex structure, which consists of the sub angular blocky and granular structures, as well as the spongy structure. The predominant pores are Channels and Vughs, partially coated with carbonate minerals and sometimes clay minerals. It was found that there is a clear discrepancy in the subsurface diagnostic horizons, since the dominance of the Calcic horizon and the Argillic horizon in the pedons soils of the study sites. These results confirm the significant effective role of Pedogenic processes and their activity in the inheritance and development of the studied soils represented by the processes of Eluviation or Illuviation and the formation of Illuvialhorizons. The study soils were classified within the order Aridisols and to the suborders Calsids and Argids. A great groups of Haplacalcids and Calciargids were diagnosed with the presence of the subgroups of TypicHaplacalcids and Typiccalciargids in the study area. [ABSTRACT FROM AUTHOR]