Adjusted Crop Coefficient for Wheat Using Energy Balance Systems in North Nile Delta of Egypt

Abstract

Accurate crop coefficient (Kc) is essential for optimizing irrigation water use as well as enlargement water productivity in agriculture. This study aims to update the Kc values for wheat in the North Nile Delta, Egypt, using an energy balance (EB) system powered by Campbell Scientific instrumentations. Field experiments were conducted during three consecutive wheat-growing seasons of 2022/23,2023/24 and 2024/25 at Sakha Agricultural Research Station, covering an area of 4.2 hectares. Actual evapotranspiration (ETa) was measured using energy balance techniques, and Kc values were derived by comparing ETa with reference evapotranspiration (ETo) from FAO Penman Monteith approach. Results showed that FAO-56 Kc values tend to underestimate Kc during the initial (ini) and late-season (end) growth stages, while slightly overestimating mid-season Kc. The obtained Kc values for wheat were: 0.43–0.68 (Kc ini), 0.75–1.02 (Kc dev), 0.94–1.11 (Kc mid), and 0.4–0.64 (Kc end), differing from FAO-56 values. The findings suggest that local calibration of Kc is necessary for precise irrigation scheduling, enhancement water management efficiency, and consequently sustainable wheat production under water-scarce conditions.