Characterization and Classification of Salt Affected Soils and Irrigation Water at Bule Hora District, West Guji Zone

Abstract

The study of soil physico-chemical properties and irrigation suitability was made on the soils of Galesa Negeso small scale supplementary irrigation located in West Guji Zone, Oromia Region. The objective of the study was to characterize, classify the soils and irrigation Water then to determine the suitability for agriculture. The physico-chemical properties of the soils were also characterized in the laboratory through the analysis of soil samples collected on depth wise. The results of the study revealed that the soil texture, bulk density, porosity, field capacity, permanent wilting point, total available water and chemical properties of soil such as soil pH, Electrical conductivity, cation exchange capacity, exchangeable catios and exchangeable sodium percentage in the soil profile of different land use systems such as Rainfeed field (Pedon1), irrigated field (Pedon2) and Fallow land (Pedon3). The highest average value of bulk density (1.36 g cm-3) was observed on the irrigated sugarcane field followed by 1.31 g cm-3 on the Rainfeed maize land and the lowest bulk density (1.20 g cm-3) was observed on the fallow land. The soil texture classes the same throughout the depth to sandy loam and sandy clay loam in the Pedon1 and Pedon2, respectively. The average value of total available water holding capacity of the Pedon1, 2 and 3 were 9.0, 11.9 and 7.9 %, respectively. The highest average value of pH (6.9) was observed on the Pedon3 followed by 6.43 on the Pedon1 whereas the lowest average value of pH (6.42) was observed on the Pedon2. The highest average values of exchangeable sodium percentage (14.43%) were observed in the Pedon1 followed by 10.34% in the Pedon2 and then followed by 7.23% in the Pedon3. In all of the land use systems the electrical conductivity & exchangeable sodium percentage of the soils was found to be less than 4dS/m & 15%, respectively, indicating that there would not be any actual and potential salinity & sodicity hazard in the soils of the study area. The sodium adsorption ratio (SAR) ranged from 11 in the irrigation water sampled from the Alfat River to 12 for Lake Habas water for the sampling at mid-rainy and mid-dry season. During the mid-rainy and mid-dry season, the EC of the different water sources varied from 151μmhos/cm to 165μmhos/cm for Alfat River and Lake Habas, respectively.The sodium adsorption ratio (SAR), electrical conductivity (EC) and RSC value were 11, (151 μmhos/cm), 0.14meq/l for Alfat River water for the sampling at mid-rainy season, respectively. SAR, EC and RSC contents of the Alfat River and Lake Habas water fell under the same class, low salinity hazard class (C1), medium sodium hazard class (S2) and safe (class1), respectively which were used for irrigation purpose according to the classification set.

Keywords: Salt affected soils, soil physicochemical properties; water quality