Crop Water Requirement and Crop Coefficient of Tef (Eragrostis tef) in Central Rift Valley of Ethiopia

Tef is the most important native cereal crop to Ethiopia and widely grown under rain-fed agriculture. Irrigation is essential in arid and semi-arid areas where rainfall is unreliable and insufficient for crop production. Rational application of irrigation water is based on the knowledge of crop water requirement. Field study was undertaken at the experimental farm of Melkassa agricultural research center located in the central rift valley of Ethiopia. Non-weighing lysimeter was used to measure daily crop water requirement of tef grown on a clay loam soil. The reference evapotranspiration was determined from daily climatic data using Penman-Monteith method and Kc was obtained from the ratio of measured crop water requirement as obtained from water balance equation to estimated reference evapotranspiration. The measured crop water requirement values tef during growth stages of initial, development, mid-season and late season were 36.4 mm, 109.9 mm, 166.5 mm, and 50.9 mm, respectively. The corresponding Kc-values as a fraction during growth stages were 0.46, 0.88, 1.03 and 0.57. Fifth-order polynomials function was found to fit well to predict the crop coefficient values as functions of days after sowing that can be applicable in similar agro-climatic region for irrigation design and water management practices. Keywords: Crop water requirement, reference evapotranspiration, Kc, drainage lysimeter, tef DOI: 10.7176/JNSR/11-15-04 Publication date: August 31 st 2020