Evaluation of Deficit Irrigation and Fertilizer Levels on Water Productivity and Yield of Tomato at Hawa Galan District, Western Oromia, Ethiopia

This study was conducted to address the critical challenges of water scarcity and inefficient input use in tomato production. The specific objectives were: 1) to evaluate the water productivity of tomato under different combinations of irrigation levels and fertilizer rates, 2) to quantify the amount of irrigation water saved using these combinations, and 3) to recommend the best water and fertilizer-saving technique for the study site. A factorial experiment was arranged in a Randomized Complete Block Design with three replications. The treatments included three irrigation levels (50%, 75%, and 100% of crop evapotranspiration - ETc) and three fertilizer (NPS) rates (50%, 75%, and 100% of the recommended amount). The results showed that the combination of 75% ETc and 75% fertilizer rate (150 kg NPS ha<sup>-1</sup>) achieved the highest water productivity (8.39 kg ha<sup>-1</sup> mm<sup>-1</sup>) and a high yield of 23,901 kg ha<sup>-1</sup>, which was statistically on par with the full irrigation and fertilizer treatment. This optimal treatment resulted in water savings of 25% (94.95 mm) compared to the full irrigation regime. It is concluded that applying 75% of both the recommended irrigation water (ETc) and fertilizer rate is the best technique for the study site, enabling significant resource conservation without compromising yield. This strategy is recommended for extension to farmers to enhance sustainable productivity.