Crop Water Requirements and Irrigation Scheduling for Selected Crops in Semi-arid Beledweyne District

Abstract

This paper aims to estimate crop water requirements and irrigation schedules for selected crops—tomato, maize, sweet pepper, and sorghum—in Beledweyne District, a semi-arid region of Somalia. The Penman-Monteith equation was used to estimate reference evapotranspiration (ET0) based on 20 years of meteorological data obtained from NASA POWER and CLIMWAT. The estimated ET0 values were then combined with crop coefficients and effective rainfall to determine crop water and irrigation requirements. The findings revealed substantial seasonal variation in ET0, with a mean of 7.46 mm day-1. Total annual rainfall was 510 mm year-1, of which 436 mm year-1 was effective. Tomato had the highest seasonal crop water requirement (987 mm) and irrigation water requirement (749 mm), whereas sorghum had the lowest requirements (731 mm and 499 mm, respectively), suggesting its suitability for water-limited conditions. The irrigation schedules indicated that water demand was highest during the mid-season growth stage. Therefore, careful irrigation management during this stage is essential to meet crop water requirements efficiently and optimize water use during this critical period of crop development. The results demonstrate the importance of crop-specific irrigation management based on local climatic conditions for improving agricultural sustainability and water-use efficiency in water-scarce areas such as Beledweyne. This model-based methodology provides a useful framework for sustainable irrigation planning, supporting livelihoods and advancing climate-resilient agriculture in semi-arid regions.