Impact of recycled wastewater irrigation on soil chemical properties in an arid region.

The present study was undertaken to assess its impacts on soil quality. Analysis for soil was done from the area used for wastewater irrigation. Soil sample were collected from ten locations such as pasture and irrigated fields of Sistan area near Zabol city. Analysis was done for Electrical Conductivity (EC) and soil texture and key chemical parameters. Results indicated that soils (sampled to 12 cm) from pasture with RWW irrigation exhibited 0.3 units of higher pH and 172, 34 and 40% higher concentrations of extractable Na, B and P, respectively. Compared with sites irrigated with surface water, sites irrigated with RWW exhibited 176% higher EC and 485% higher Sodium Adsorption Ratio (SAR). Comparison of soil chemical properties before and 3 or 5 year after RWW irrigation on two parts of pasture also revealed the following findings: 89 to 136% increase in Na content; 44 to 63% increase in B content and 88 to 116% increase in P content at the surface depth. Regular monitoring of site-specific water and soil and appropriate management are needed to mitigate the negative impacts of sodium and salts accumulations.