Evaluating phosphate leaching losses into the agricultural drainage water at Al-Hassa Oasis, Kingdom of Saudi Arabia

(Abdul Rahman bin Mohammed urban, Abdullah bin Musa al-Gosaibi and Ben Ali Abdul Khaliq humans)

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Abstract

In the current study, drainage water samples were analyzed for their phosphate (PO43-) concentrations. The samples were collected twice a month (beginning and mid of the month) from November 2008 till April 2009. They were collected from the D1 (8 locations) and D2 (5 locations) main drainage ditches in the Al-Hassa Oasis, KSA. The sampling locations were assigned by the GPS technique. The total samples collected from both ditches were 96 and 60, respectively. The selection of sampling locations were done to cover the cultivated area avoiding any interference with rural, municipal and industrial activities. While, the study period was assigned to include the period of the most agricultural activities in the Oasis that involve date palm soil fertilization and irrigation, as date palm cultivation covers 70% of the cultivated area that exceeds 8,200 ha of the 20,000 ha total area of the Oasis. The obtained results showed that there were significant differences between PO43- concentrations associated with their different locations (in each or among both ditches) and with their various sampling times. In the D1, PO43- values ranged between 0.76 and 1.79 mg/l with the highest value (1.79 mg/l 177;0.04) occurring on beginning of March 2009 (T9) and at the D1-5 location. In the D2, they ranged from 1.03 to 1.85 mg/l with the highest value (1.85 mg/l 177;0.04) was on mid March 2009 (T10) at the D2-1 site. Generally, the highest PO43-concentrations were spatially observed within the internal part of the Oasis in the middle of both dishes, whilst the lowest values were at their terminals. Temporally, the values were low at the starting time of the study period reaching their maximum values in March after which they declined. It is thus concluded from these results that the agricultural activities and its intensity in the Oasis impose vital impacts on PO43- leaching losses. Thus, environmental consequences of such losses on natural resources in the Oasis ought to be recognized taking into considerations the long-term sustainable farming programs adopted by the responsible authorities in the Oasis. Key Words: Al-Hassa Oasis, Phosphate, Leaching loss, Environmental Pollution, Nutrients.
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