ASSESSMENT OF SALINITY STATUS OF SOILS AND IRRIGATION WATER QUALITY IN DRY SEASON WHEAT PRODUCTION IN SELECTED DISTRICTS OF WEST HARARGHE ZONE, ETHIOPIA

Abstract

Soil salinity problem is predominantly severe in developing countries, particularly in arid and semiarid regions, resulting in short-term damage to people's livelihoods and long-term repercussions on the country's food security. It is also a major challenge in Ethiopia and west Hararghe in particular where small-scale irrigated agriculture is practiced. Against this backdrop, this study was conducted to assess the soil salinity and irrigation water quality in dry season wheat production in Dhungeta, Hule Mandhera, and Kinteri irrigation sites in west Hararghe Zone, Ethiopia. Based on in situ field survey, pit opening, surface soil and irrigation water sampling sites were identified. A total of 30 composite surface soil samples were collected from a depth of 0-30 cm. Three pits were opened from which 15 samples from different depths and 9 composite irrigation water samples were collected by mixing several sub-samples. Soil and irrigation water data were analyzed by using R Studio. The soil texture was sandy clay loam for Dhungeta and Kinteri whereas sandy loam was recorded for Hule Mandhera. The mean bulk density of surface and pit soil, at Dhungeta (1.43 gcm-3 and 1.49 gcm-3), Hule Mandhera (1.48 gcm-3 and 1.5 gcm-3), and Kinteri (1.44 gcm-3 and 1.45 gcm-3) which is within an acceptable range. The mean of soil and water pH at Dhungeta (7.47, 7.00) and Hule Mandhera (7.86, 7.94) and Kinteri (7.93, 7.45) fields were grouped in moderately alkaline levels for soil and the normal range for irrigation water, respectively. The electrical conductivity of surface and sub-surface soil was (1.11, 0.24 dSm-1), (2.32, 1.65 dSm-1) and (1.11, 0.65 dSm-1) for Dhungeta, Hule Mandhera and Kinteri, respectively. The salinity hazard of irrigation water at Dhungeta was medium (0.67 dSm-1), Hule Mandhera high (1.03 dSm-1) and Kinteri (0.99 dSm-1). In the same order of sites, soils were low to medium in OC content ranging (0.51 - 1.96%), (0.54 - 1.88%) and (0.48 - 1.92%). The CEC of soil ranged from medium to high while PBS was high in Hule Mandhera and high to very high in other sites. Exchangeable bases were in the order of most agricultural soil which is Ca > Mg > K > Na for both surface and subsurface soil samples of the entire study sites. The salinity/ sodicity qualify parameter showed that 10%, 20% and 40% of collected samples from Dhungeta, Kinteri and Hule Mandhera had salinity problem respectively. The total mean of dissolved salt showed water has no restriction for use at Kinteri (153.6 mg L-1) and Dhungeta (426.67 mg L-1) while slight to moderate restriction of water for use was recorded at Hule Mandhera (708.27 mg L-1). The sodicity (alkalinity) hazard class of irrigation water was S1 (low sodium hazard). The mean of residual sodium carbonate was a marginal hazard at Hule Mandhera and safe at Dhungeta and Kinteri. Based on the permeability index, magnesium hazard water was found to be suitable for irrigation. Kelley’s index, Percentage sodium (Na+ %), and potential salinity specified that Hule Mandhera water is unsuitable whereas Dhungeta and Kinteri water were suitable for irrigation. irrigation water grouped as a low restriction (70-85) based on the irrigation water quality index. Generally, there is a prospect to decide that the irrigation water quality of the study sites is suitable for wheat production.