Effects of Irrigation with Disposed Produced Petroleum Water on the Soil and Plants at Khartoum Refinery, Sudan

Abstract

This study aimed to assess the effect of irrigation interval with disposed produced petroleum water (DPPW) on the soil and vegetation cover at Khartoum Refinery Company (KRC). Thirty-six soil samples (at depths of 0-30, 30-60 and 60-90 cm) were taken from tree plantation blocks. The treatments were P0 (none irrigated, as a control) and P1 and P2 were irrigated for four and eight years, respectively, and were analyzed for pH, cation exchange capacity (CEC), total soluble Na+, Ca++, Mg++ and Cl-. Twenty-one samples of tree leaves were collected from P0, P1 and P2 and analyzed for Na, Ca and Mg. The results showed that at the soil surface (0-30 cm) no differences within and between blocks in pH that was about 7.0 where the CEC of P0 and P2 have lower content compared to P1. Application of the DPPW increased the soluble Na+ of P1 and P2 compared to P0 (2.2, 0.46 and 0.04 Meq/L respectively), and the same trend was shown by soluble Ca++ (74.5, 18 and 2.5), and Mg++ (3.0, 2.5 and1.0). Cl- content increased as irrigation interval increased (4.5, 104.5 and 30.0 Meq/L for P0, P1 and P2, respectively). Systematic decrease of all soil chemical content with depths was shown for P0, P1 and P2. For the plant, there was an increase in Na as irrigation interval increased (50.67, 516.67 and 723.33 for Po, P1 and P2 respectively), whereas Ca and Mg increased in P1 compared to P2 and P0. The risk of accumulation of soluble salts is expected to occur with time, therefore, specific treatments to decrease the salts content of DPPW are crucial.