Long-Term Effects of Municipal Wastewater Irrigation on Some Properties of a Semiarid Region Soil of Iran

To investigate the effect of long-term irrigation of wheat farms on the soil properties, a field study was carried out in Varamin Station located in southern Tehran, Iran. The soil samples were collected from the area with 29 years using wastewater irrigation and comparing the results with soil properties extracted from the previous control profile of the pedological study in 1981. Some soil properties of the samples such as electrical conductivity (EC), soil reaction (pH), organic carbon (OC), bulk density (pb), and saturate hydraulic conductivity (Ks) were measured for comparison. The obtained paired data were analyzed with T-test. The results showed that using wastewater significantly increased the soil organic carbon and bulk density in depth of 0–20 centimeters (p<0.05). Saturated hydraulic conductivity in depth of 0–20 centimeters and soil reaction in both depths of 0–20 and 20–40 centimeters significantly decreased (p<0.05). The reason may be due to filling of colloidal particles suspended in wastewater within the soil porosity. Wastewater quality and, possibly soil properties, appear to play an important role in the effect of using wastewater irrigation on the soil physical properties.