Water Productivity Functions and Water Consumption Indicators for Faba Bean under Deficit Irrigation Conditions

Abstract

This study aims to evaluate the deficit irrigation strategy as a means of managing irrigation water and improving its use efficiency in faba bean production. It investigates the effects of different irrigation water quantities on growth and productivity and estimates some economic indicators of water consumption. The experiment was conducted in the Al-Shatwia area, south of the city of Zawia, during the fall and winter seasons of 2023/2024, using a Line Source Sprinkler Irrigation system. Seven different water treatments were applied to experimental plots, each measuring 1.5 meter × 6 meter. The volumetric soil moisture content was estimated at the beginning and end of the season. Irrigation amounts were monitored using a Class A evaporation pan and the modified Hargreaves-Samani equation, in addition to using a TDR device to track moisture variations. The study included measuring the number of pods when they were full and moist, as well as both the wet and dry weights of the grains. The water production function (WPF), water use efficiency (WUE), and return per unit of water (WPy and WP_M) were estimated. The results showed that changes in irrigation water amounts led to a non-linear decrease in productivity. The highest average dry grain yield was 2.37 tons/hectare when 2,617.7 m³/hectare of irrigation water was applied. The optimal irrigation water values required to achieve the highest yield were determined to be 3,027.08, 2,674.5, and 2,494.5 m³/hectare for moist pods, wet grains, and dry grains, respectively. The study concluded that precise irrigation water management using deficit irrigation can enhance water use efficiency without significantly affecting productivity, thereby promoting the feasibility of this technique in areas with limited water resources.