Optimal irrigation water allocation for enhanced productivity of haricot bean (Phaseolus vulgaris) and economic gain: An experiment conducted in the semi-arid area of Ethiopia

Haricot bean is an important cash crop widely grown in Ethiopia. This study was conducted to assess the effects of different irrigation levels on haricot bean yield and its related attributes. The experiment contained five irrigation levels: 60, 80, 100, 120, and 140 % manageable allowed depletion (MAD). The results indicated significant effects of varying irrigation levels on haricot bean yield and related attributes. The highest haricot bean yield was observed under the 80 % manageable allowed depletion treatment, with yields of 25.0, 26.0, and 23.43 qt/ha during the 2016, 2017, and 2018 experimental years, respectively with no significant difference in 100 % manageable allowed depletion. The lowest yield was recorded under the 140 % manageable allowed depletion treatment, with 18.1, 18.6, and 15.47 qt/ha during the 2016, 2017, and 2018 experimental seasons, respectively. This treatment showed significant variations compared to the other irrigation levels. The maximum average haricot bean yield of 24.80 qt/ha and the minimum yield of 17.8 qt/ha were observed under the 80 % and 140 % manageable allowed depletion treatments respectively, over the three experimental years. The lowest water productivity of 4.47 and 4.40 kg/mm was recorded under the 120 % and 140 % manageable allowed depletion treatments, while the highest values of 6.08 kg/mm and 6.07 kg/mm were obtained under the 100 % and 80 % manageable allowed depletion treatments, respectively, over the three experimental years. Moreover, the 80 % manageable allowed depletion treatment yielded the highest economic gain of 30,117.5 birr per hectare. Therefore, based on the current study's findings, it is recommended that applying 80 % manageable allowed depletion under furrow irrigation is more favorable for haricot bean production in semi-arid areas of Ethiopia and similar ecological contexts. • Irrigation water allocation is the efficient and fair water distribution for sustainable use. • Optimal irrigation scheduling for haricot bean was determined. • Soil moisture was monitored gravimetrically during the field experiment.