Irrigation with ponds effluent – impacts on soils and groundwater
Waste stabilization ponds – the source of effluents to be reused beneficially for irrigation purposes, have been discussed together with specific guidelines and criteria regulating the practice of wastewater irrigation. The impacts of long-term irrigation with ponds effluent on soils and ground water quality have been assessed by means of a specific case study of pasture irrigation at Imbwa farm in Chitungwiza, Zimbabwe during the period 2000–2001. Results show that the quality of naturally acidic soils has been improved in terms of increase of the pH and the essential nutrients content. The metals content of soils were far below the recommended maximum values. Adverse impacts on ground water were found with respect to metals – Cd, Zn and specifically Cr, which showed high background values increased by the irrigation practice. High contamination with respect to ammonia, and pronounced pollution with respect to EC, nitrate, phosphate and FC was found as well. Recommendations to improve the present practice have been made.