Evaluation of Surface and Ground Water Quality for Irrigated Agriculture in Ziway Area

Irrigation water, irrespective of its source, contains a great deal of harmful substances that may reduce crop yield and deteriorate soil quality. The quality of available water sources, in this regard, should be evaluated before using them for irrigation purposes. Therefore, this study was aimed at assessing the quality of irrigation water that farmers used in the area and suggesting possible management options. A total of 24 water samples were collected from 4 extensively used bore holes and 2 abstraction points along the Bulublla River in 2016 and 2017. Fourteen quality parameters were applied following standard laboratory procedures. General linear model of two ways analysis of variance was used to evaluate quality parameters across the locations and water sources. The results revealed that about 64.3% of the parameters showed remarkable variation at P<0.05 across water sources while 35.7% showed variation across locations. Moreover, about 93% of the quality parameters showed higher values in groundwater samples compared to surface water. This suggests that the quality of groundwater would be an issue in the area. Sodium adsorption ratios in all locations were found within acceptable limits for irrigation, but its highest value was observed in groundwater samples. Other secondary water quality indices had also remained very high in ground water samples. Thus, paying attention to thequality of groundwater was very important to maintain soil productivity. In general, all crops could be grown effectively with the assessed water sources. However, management practices such as; fallowing, conjunctive use of both sources and choice of salt tolerant crops might help to maximize yield if crops were irrigated with groundwater.