Effects of Automated Irrigation Systems and Water Regimes on Soil Properties, Water Productivity, Yield and Fruit Quality of Date Palm

Applications of modern micro-irrigation methods are inevitable for optimum water use due to the limitations imposed by irrigation water resource scarcity. Regardless of water shortages and associated challenges in dry areas, the irrigation of date palm trees consumes an excessive quantity of water annually using conventional irrigation methods. Therefore, the present study was designed to evaluate the effects of modern surface and subsurface micro-irrigation systems, i.e., subsurface drip irrigation (SSDI), controlled surface irrigation (CSI), and surface drip-irrigation methods (SDI), with different irrigation water regimes, i.e., 50%, 75%, and 100% irrigation water requirements (IWRs), on the yield and fruit quality of date palms (cv. Khalas) and water conservation in the dryland region of Al-Ahsa, Saudi Arabia. The effects of three irrigation methods and IWRs were studied on macronutrients and soil chemical properties at three depths (0-30, 30-60, and 60-90 cm), as well as on water productivity, yield, and the fruit quality of date palms. The study was carried out over two years and was designed using a two-factorial randomized complete block design (RCBD) with nine replications. The results indicated that electrical conductivity (EC) increased as the depth of the soil increased. The soil chemical properties did not change much in all experimental treatments, while soil pH values decreased with the soil depth from 0-30 to 60-90 cm. Although the maximum fruit yield (96.62 kg palm(-1)) was recorded when 100% irrigation water was applied in the SSDI system, other treatment combinations, such as SDI at 100% IWR (84.86 kg palm(-1)), SSDI at 75% IWR (84.84 kg palm(-1)), and CSI at 100% IWR (83.86 kg palm(-1)) behaved alike and showed promising results. Similarly, the highest irrigation water productivity (2.11 kg m(-3)) was observed in the SSDI system at 50% IWR, followed by the SSDI at 75% IWR (1.64 kg m(-3)) and 100% IWR (1.40 kg m(-3)). Fruit quality attributes were also promoted with the SSDI system at 75% IWR. Hence, the SSDI method at 75% IWR appeared to be an optimal choice for date palm irrigation in arid areas due to its positive impact on water conservation and fruit characteristics without affecting soil chemical properties.