Effect of sewage sludge application and wheat (Triticum aestivum L.) planting on the availability and fractionation of copper in some calcareous soils of Chaharmahal-Va-Bakhtiari

Information about distribution and availability of copper (Cu) in calcareous soils treated with sewage sludge and after wheat planting is essential in management of sewage sludge application. This study was performed to evaluate Cu availability (using 3 extractants) and its fractionation in 10 calcareous soils of Chaharmahal-Va-Bakhtiari province before and after treated with sewage sludge (1% w/w) and also after wheat plantation in greenhouse conditions. The results of this study showed that among 3 extractants, mean of Cu extracted by Mehlich 3 increased (27%) significantly (P<0.05) after sewage sludge application and decreased (34%) significantly (P<0.05) after planting. After sewage sludge application and planting, Cu-fractions were changed significantly (P<0.05). After sewage sludge application, mean of Cu exchangeable, Cu associated with carbonates, Cu associated with iron-manganese oxides, Cu associated with organic matter and residual increased 89, 22, 17, 26 and 6%, respectively. After wheat planting in treated soils, mean of exchangeable Cu, Cu associated with carbonates and Cu associated with iron-manganese oxides decreased 65, 73, 17, and 11%, respectively and Cu associated with organic matter (47%) and residual Cu (8%) increased. The results of the present research showed that difference in supplier Cu fractions could be used to describe difference for Cu extracted with one-step methods after treatment.