PLANT-GROWTH AND UPTAKE OF MINERAL ELEMENTS AT AN OILY SLUDGE LANDFARMING SITE IN KUWAIT

Oily sludge landfarmed in Kuwait soil contains higher concentrations o f certain elements than that of the untreated of, soil, e.g. S, Cu, Cr , Zn, Pb, Ni, Mo and V. The growth and elemental content of three diff erent plants grown on a sandy soil previously treated with different c oncentrations of oily sludge were studied. Tested plants differed in t heir response to landfarmed oily sludge; ryegrass was the least affect ed followed by oats, then barley. Uptake of elements differed both qua litatively and quantitatively between test plants. In barley, Zn incre ased in plants cultivated in soil treated with oily sludge, whereas ot her metal concentrations were reduced or not affected, namely, Cu, Pb, Ni, V. The uptake of P was greater in plants grown on treated soil co mpared with those on untreated soil, whereas Na, Ca, K, were either re duced or unaffected. In oats, Zn, Ni, Cu, Pb, V, were not significantl y changed. Uptakes of K, Ca, P, and Na in plants from treated soil wer e higher than that of the control. In ryegrass, heavy metal concentrat ions were either reduced or remained the same as that of the control. In all cases, concentrations of essential heavy metals and other true elements under investigation were still lower than the levels consider ed to be sufficient for micronutrients. Thus, the oily sludge was a so urce of certain micro-nutrients which were deficient in the sandy soil . Further, it appears that uptake and distribution of elements in plan t tissues were both highly variable according to the plant, species, a nd the soil characteristics.