To study the genesis and developments of illuviation horizons in Iraqi arid region, three pedons were selected in the Pripj region bottom, which formed the larger region in Iraqi southern desert in Muthana governorate, the pedons were morphologically described and obtained disturbed soil samples from every horizon for the purpose of conducting some physical and chemical analysis, in addition to undisturbed soil samples from second horizon to study the micro morphological property.
The result of micro morphological properties examination emphasized existence development in studied soils, through some micro morphological appearances like Argillans and Calcians, which emphasis the movement for some soil composed from above horizon to the lower as result to active some soil formation process. Also the results showed absence the clay skin clearness in some cases because its crashed by swelling and shrinkage process for clay minerals and to additions for some materials as carbonates in alluvial horizon. The examination for thin section showed supremacy microstructure type complex with existence the pores type Vahgu which covered partly with carbonate minerals accumulation sometimes clay minerals. We showed difference in nature of sub surface diagnosis horizons, the supremacy was to Argillic and Calcic horizons in all pedions. These results indicated the roll of dominant ecological factor in activation some pedological process, which contributed to formation and development that horizons like the darkness development process and loss and illuviation process in addition to salinity remove Calcification and Decalcification. Studied soils classification within Aridisols order, Argids and Calsids sub orders, also within Haplacalcids and Haplargids great soil group and sub great soil group Typic Haplacalcids and Vertic Haplargids in the region.