Trace metal concentration in durum wheat from application of sewage sludge and commercial fertilizer

Repetitive application of commercial fertilizer continually introduces potentially toxic trace metals to the soil. Such metallic elements are not biodegradable, accumulate in the soil, and are subsequently taken up by food crops. Sewage sludge, often disposed of in landfills, contains high nutrient and organic contents and is now being recycled and beneficially applied to agricultural land worldwide in increasing amounts. Metals in sewage sludge are generally organically bound and generally less available for plant uptake than the more mobile metal salt impurities found in commercial fertilizers. The purpose of this project was to determine the regions of metal accumulation within the wheat plant and to compare metal uptake by plants receiving a high metal load through the application of contaminated sewage sludge with that by plants receiving a commercial fertilizer and a metal-free control. Results of this research indicate that despite the high metal load received by the sludge-applied replicates, metal concentrations in those plants were similar to the concentrations resulting from application of the commercial fertilizer and the metal-free nitrogen control. Little or no change in metal concentration was seen between plants grown with fertilizer addition in comparison to the control plants. (C) 2000 Elsevier Science Ltd. All rights reserved.