Evapotranspiration and Crop Coefficient for Haricot Bean ( <i>Phaseolus vulgaris L</i> .) Using Nonweighing Lysimeter Under Semiarid Climate of Melkassa, Ethiopia

The primary objective of irrigated agriculture is to produce crops with the help of irrigation. This field study was conducted during the 2017 and 2018 cropping seasons at the experimental farmland of Melkassa Agricultural Research Center, Ethiopia. The actual crop evapotranspiration and crop coefficient for the haricot bean were determined from nonweighing lysimeter studies. The soil–water balance approach was applied to compute the actual crop evapotranspiration of the haricot bean, whereas the reference evapotranspiration was computed with the help of the Penman–Monteith method. The crop coefficient was obtained from the ratio between the measured crop evapotranspiration and the reference evapotranspiration. The seasonal crop evapotranspiration for the haricot bean was 493.0 and 410.1mm during the experimental period of 2017 and 2018, respectively. The mean crop evapotranspiration for the haricot bean over the two experimental years was 451.6 mm. The mean locally produced actual crop coefficient values were 0.5 at the initial stage, 1.16 during the mid‐season stage, and 0.67 at the end‐season stage. The average FAO‐adjusted Kc value over the two experimental years was 0.41 at the initial stage and 1.14 during the mid‐season. The FAO‐adjusted crop coefficient Kc values slightly differed from the crop coefficient Kc values developed. The findings provide valuable insights for enhancing the design and management of irrigated haricot bean production in the region. The specific crop coefficient Kc values determined for different growth stages are crucial for optimizing irrigation scheduling and improving water‐use efficiency, contributing to sustainable haricot bean production in the semiarid environment.