Water scarcity is a major constraint facing vegetable production sustainability in open field farming of arid regions like the Kingdom of Saudi Arabia. This study was carried out in an open field of the Research and Training Station of King Faisal University in the eastern region of the Kingdom. The objective was to assess the influences of the polymer addition (PA), deficit irrigation regime (DIR), and their combination on the production and water use efficiency (WUE) of muskmelons. PA treatments of 0.0, 0.2 and 0.4% and the irrigation treatments of 100, 75 and 50% of reference evapotranspiration (ET<sub>o</sub>), were imposed throughout the growth stages of muskmelons under surface drip irrigation (DI) and subsurface drip irrigation (SDI). The polymer addition of 0.4% enhanced the field water holding capacity of the medium sandy soil within the locality of the emitters by 43.6%. The soil water content of the surface layer within the vicinity of the polymer amended soil layer increased in a range of 72.4 to 99.4% to the combined influences of the 0.4% PA with the DI and SDI, but were marked more under the SDI. The combination of the 100% ET<sub>o</sub> DIR with polymer additions significantly (P < 0.05) enhanced the muskmelon fruit yield (MFY) under the SDI compared to DI. The PA of 0.4% improved WUE and MFY by 67.7, 70.4% under the SDI, and 58.6, 24.2% under the DI, respectively. Without the polymer addition (0.0% PA), the MFY significantly (P < 0.05) decreased with the increase of the DIRs under both DI and SDI.
The current study is aimed to assess water use efficiency and evaluate economic viability of hydroponic and conventional production of barley green fodder by keeping in view the water scarcity challenges in Saudi Arabia. A hydroponic system and open field experimental plot was used to evaluate the water use efficiency for different irrigation regimes. Economic indicators for both production systems are estimated and compared to accomplish economic assessment. Estimated indicators include returns from inputs and net profit; benefit-cost ratio; break-even levels of prices, production, and yield; returns over variable cost; and returns on investment. Results indicated that the yield of barley green fodder produced under hydroponic conditions overtopped the yield under conventional cultivation. Under hydroponic and conventional conditions, WUE was decreased with increasing the harvesting date. However, WUE for the hydroponic technique was much higher than the conventional one. The returns and net profits supported the conventional cultivation methods, where lower dry matter content coupled with higher fixed and variable costs incurred by the hydroponic technique outweighed returns leading to economic loss. Cost-benefit ratios, returns over investment, and break-even prices and yield suggested that growing barley fodder under the hydroponic technique is economically not suitable for small-scale farming. However, regarding water conservation, hydroponic barley cultivation showed superiority over conventional field cultivation. Further research on the adoption of hydroponic fodder cultivation is highly recommended for water-scarce arid regions, such as the Kingdom of Saudi Arabia.
Date palm needs sufficient water of acceptable quality to reach its potential yield. The present study conducted in Al-Hassa Oasis located in the Eastern Region of the Kingdom of Saudi Arabia aiming to estimate the daily, monthly and annual actual evapotranspiration (ETa) for date palm using Landsat-8 satellite data during 2017/2018. Also, an attempted was made to compare between the computed ETa and the actual water applied in the field. The Surface Energy Balance Algorithm for Land (SEBAL) supported by climate data was used to calculate the ETa. The SEBAL model outputs were validated using the FAO Penman-Monteith method coupled with field observation and measurements. The results showed that the highest daily ETa value observed during the summer season was 9 mm.day−1, and the lowest value was 2 mm.day−1 in winter. The mean monthly water applied in the farms was 15% higher than that suggested by SEBAL during the peak summertime. The annual ETa varied between 800 and 1,400 mm.year−1, while the annual irrigation requirement for date palm was in the range of 11000 – 13000 m3.ha−1. The validation measure showed a significant agreement level between the SEBAL model and the FAO Penman-Monteith method with RMSE of 0.84 mm.day−1. The study concludes that the ETa calculated from the satellite data and the SEBAL model is useful for guiding the daily operation of date palm water management at the farm scale. Also, this information is essential for water planners and policymakers to formulate strategies and make decisions for managing water resources over large agricultural areas.
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