THE EFFECTS OF WASTEWATER IRRIGATION ON AGRICULTURAL SOILS
In arid and semi-arid areas, wastewater is often recovered for crop irrigation, contributing to the sustainable agriculture. Although positive effects have been observed on crop yields (50-80% growth) due to wastewater nutrients, the reuse of untreated wastewater harms both the environment and human health. Soil is mostly affected by excess salts, sodium, nutrients and heavy metals in wastewater. High salinity affects the upper layer of soil (0â€“30 cm); sodium and chlorine reduce crop yields by 40%; high content of organic matter in wastewater decreases soil pH, and heavy metals and pathogens enter the food chain. Irrigation technology is also important: sodium and salinity are higher in sprinkler than in furrow or subsurface irrigation; subsurface drip irrigation is more effective in reducing soil pathogens than surface drip irrigation. This paper examines the effects of wastewater irrigation on soil salinity, sodium, heavy metals and pathogen contamination.