Estimation of Actual Water Requirements and Water Productivity of Date Palm (Phoenix dactylifera L.) cv. Barhi under the Conditions of Southern Iraq

Date palms (Phoenix dactylifera L.) struggle in arid places due to water scarcity and rising demand. Therefore, we must find more efficient ways to water them to maintain economically viable water use. Researchers in the southern portion of Basrah Governorate (Abu Al-Khasib District) employed the bubbler irrigation method to analyze water productivity under different irrigation levels and calculate Barhi date palm water requirements in 2023 and 2024. ETO was calculated using the US Class A Pan method. We then adjusted the crop coefficient (Kc) using FAO calculations to account for local climatic parameters as wind speed, relative humidity, and plant height. T1 (45%), T2 (65%), T3 (85%), and TC (100%) irrigation levels represented varied proportions of water demand. Seasonal water application rates per tree were 99, 143, 188, and 221 m³. Nine replications produced 36 experimental units using a randomized complete block design (RCBD). Daily ETo readings ranged from 2.86 to 13.33 mm/day, averaging 7.8 mm/day annually. Across all crops, ETc adj was 2955 mm/year, while Kc ranged from 0.77 to 1.15. Summer and winter watering frequency disturbances occurred at 5-day and 32-day intervals. Analysis of variance among irrigation settings revealed significant differences in water productivity and agricultural output. Treatment 1 had the highest water productivity (0.77 kg/m³), followed by T3, T2, and TC (0.59, 0.54, and 0.50 kg/m³). T3 and TC yielded the most at 110 and 111 kg/tree, respectively, with no difference. According to research, increasing irrigation water did not increase productivity correspondingly but did diminish water efficiency. Date palms in water-scarce areas can be irrigated at 45% of the total need (T1) without a yield drop, indicating that this strategy is practicable.