Physicochemical Soil Properties of Tendaho Irrigation Project Area and their Significance in Sustainable Sugarcane Production

In order to enhance the sugar production in the country, the government of Ethiopia is presently establishing the sugarcane farm in lower Awash plains with the construction of Tendaho dam at upstream near Logia town to make water available for irrigation and set-up sugar factory for processing sugar. Prior to implementing the project, this feasibility study was carried out in 2005. The project area, covering about 86000 ha, lies between 11° 30’ to 11° 50’ N latitude and 40° 45’ to 41° 03’ E longitude. The potential irrigable area covers both left and right banks of Awash River course. The upstream area is occupied by Dubti and Boyale farms, middle stream covers Dit Bahri farm, Bokaiti and Galifage area which comprises soils developed on lacustrine and old alluvial deposits. Downstream area, located below Assaiyita and extending up to Gamari and Afambo Lakes, is intensively cultivated and comprised of recent fertile alluvial soils. A detailed soil survey was carried out on 500 m × 500 m grid consisting 3196 auger holes and 105 soil profile observations. Based on laboratory analysis and field observations, the ranges in physicochemical characteristics were summarized. There were three dominant textural classes namely, silty clay loam, silty clay and clay. Soil reaction (pH), ECe, ESP, CEC, organic carbon (OC), available P and available K ranged between 7.54 to 8.44, 0.64 to 39.5 dS m⁻¹, 4.9 to 79.4%, 33.5 to 61.3 cmol(p⁺)kg⁻¹, 2.0 to 7.7 g kg⁻¹, 7.0 to 30.7 mg kg⁻¹ and 400 to 645 mg kg⁻¹, respectively. Major hydraulic properties influencing water availability and irrigation scheduling for sugarcane included infiltration rate, hydraulic conductivity and water holding capacity. Basic infiltration rate varied from 0.2 to 2.2 cm h⁻¹. In-situ hydraulic conductivity varied from 0.08 to 1.48 m d⁻¹. Water holding capacity varied from 180 to 220 mm m⁻¹ soil depth. These data were used for planning, design and scheduling of surface irrigation for sugarcane cultivation.