Salinization affects many irrigated soils mainly due to the use of brackish water in arid and semi-arid areas. This study was conducted in north western part of Lake Ziway, Adami Tulu Jido Kombolcha Woreda in the Central Rift Valley region of Ethiopia. The aim of the study was to assess the impact of ground and surface water use on soluble salt rise in soil and its effect on plant yield and biomass. Soil and water samples were systematically collected from surface and ground water irrigated fields for laboratory analysis and glasshouse experiment. The ground water had 0.98 ds/m electrical conductivity whereas surface water had 0.61 ds/m. The ground water irrigated soils from the study site had an electrical conductivity of 2.57ds/m while the surface water irrigated soils had 1.2 ds/m. Glass house experiment was carried out and results showed that after glass house experiment, the ground water treated soils were found to have less electrical conductivity of 1.27 ds/m than that of surface water treated soils having 1.37 ds/m. The ground water irrigated soils were not significantly different from the surface water irrigated soils in electrical conductivity level. There was no significant variation between surface and ground water irrigated plants in plant growth parameters (P<0.05). However, the yield was found to be affected by the salinity level. In conclusion, the ground water was found to be slightly saline and soil analysis results before experiment showed a moderately low salinity level. This could have resulted from irrigation water mismanagement. Therefore, there is a need to regulate irrigation water use in the study area.

Key words: Soil salinity, irrigation water, Ethiopia, ground water salinity.