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Water percolation in upper soil at Wadi Shueib in Jordan was investigated using different irrigational methods and amounts of irrigation water. Four investigative periods were designed: two during the summer and two during the winter. The percentage of recharge from irrigated plots ranged from 42% to 78%, depending on the amount of irrigation water and the climatic conditions that prevailed in the investigated area. The main factor that controlled the amount of percolation was soil water content. Different methods of irrigation showed apparent variations in the amount of water losses. The covered fields (mulched and subsurface methods) had the lowest water consumption as compared to the uncovered plots (bare and meandering irrigational methods). This is mainly due to the reduction in surface evaporation from the topsoils. Accordingly, any improvement in water use efficiency should take this factor into consideration.
This study was conducted in an arid area in southern Jordan to investigate the appropriateness of using treated wastewater for the cultivation of salt-tolerant fodder cover plants (i.e. Tamarix sativa, Medicago sativa, Pennisetum glaucum, and Atriplex hallimus) in Al-Lajoun Valley and its environmental impact in terms of heavy metal concentrations like copper, lead, chromium, and cadmium in soils and leaves in the context of arid land revegetation. Although the treated wastewater contains higher concentrations of Cu, Pb, Cr, and Cd than the Jordanian recommended maximum concentration of metals in irrigation water, the results showed no accumulation of heavy metals in irrigated soils and plants. Concentrations of metals in wastewater-irrigated soils were much lower than the critical soil total concentration. In addition, heavy metal concentrations in leaves of the grown cover plants were within the normal range in plants, which is advantageous if such plants are to be used as fodder for animals. Pollution load index and plant concentration factor varied with the grown cover plants. High transfer values of Cu, Pb, and Cr from soil to particularly P. glaucum were observed. An inverse relationship between transfer factor and total metal concentrations also was observed. In conclusion, treated wastewater can be used, at least in the short term, as a practical solution for irrigation water shortage to minimize soil degradation and for revegetation purposes.
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