In the arid and semiarid regions, the use of treated sewage water increases as an alternative for non-renewable resources in irrigation. The objective of this research is to identify the effect of irrigation with sewage effluent and well water for long periods on some soil properties, as well as to identify the spatial variability of some characteristics of soil using geo-statistics methods. To achieve such goals soil samples on grid 50 m apart have been collected from three farms for forage crop production projects at Al-Hair, 30 km south of Riyadh. 236 soil samples were taken at two depths (i.e. surface and subsurface). Results showed that the EC values ​​where higher in subsurface compared to surface in all farms, depending upon the source of irrigation. These values were (3.48, 2.20 and 2.21 dSm^-1)  in the surface layers of the first, second and third farms respectively, while the respective values in the subsurface layers reached (4.53, 3.23 and 2.60 dSm-1) respectively. On the other hand the concentrations of Zn, Cu, and Fe. Ni were higher at the sewage treated farms than the well irrigated ones. As the values were 28.87, 16.95, 4225, and 72.26 mg.kg^-1 for Zn, Cu, Fe. Ni in first farm and 42.4, 60.5, 11215, and 180 mg.kg^-1 for the second farm. While for Pb in the surface layer of the soil at the first, second and third farms were 63.01, 37.10 and 27.69 mg.kg^-1 soil, respectively. The spatial variability of the pH values of the surface and subsurface layers at a range = 50.60, 69.90 meters, respectively. In conclusion, results of geostatistic showed the spatial variation for soil properties were very minimum and the calculated enrichment factor did not show any contamination in soils of the studying farms with exception of As.