Evaluation of the Quality of Irrigated Soil by Wastewater in Taiz City, Yemen

Abstract

A field study was conducted for soil which was irrigated by partially treated and untreated sewage in the Surroundings of Taiz City. The study aims at evaluating the level of degradation on agricultural soil in the study area as a result of the wastewater application. Four samples of soils have been collected from four different sites within the areas of Al-Qurf, Al-Hawajalah, Al-Buraihy and Hidran Al-Dabab, in addition to a control sample of soil from agricultural land irrigated only from seasonal rainwater at Mafraq Sharab. The results of mechanical analysis of the soil showed that the soil texture at the four different sites varied from one location to another. For instance, at Al-Qurf and al-Hawjalah areas, the soil texture was found to be Silt-Loam, whereas at Al-Buraihy and Hidran Al Dabab, the soil texture was clay, while the soil texture in Mafraq Sharab was loam. The results of the chemical analysis of the soil samples indicate that the soil irrigated from partially treated and untreated wastewater compared to the irrigated soil of rainwater was most affected by the high level of salinity and the calcium carbonate ratio. In addition, the chemical and heavy metals elements contents of the soil are high which is probably accumulated in soil over several years. This suggests an action of rapid treatment of land where salinity has accumulated significantly through soil rehabilitation, including soil tillage mixed with limited quantities of gypsum and soil leach with fresh, low-salty water, and thus soil cultivation with barley or sorghum yield and rotation of freshwater and treated wastewater irrigation.