Phytoavailability of Lead (Pb) for Corn and Sunflower as Affected by Pb-enriched Sewage Sludge and Cow Manure

Abstract

This experiment was aimed to investigate the influence of Pb enriched sewage sludge and cow manure on Pb availability to sunflower (Helianthus annuus L.) and corn (Zea mays L. Single cross 704). A loamy sand soil was treated with organic and inorganic Pb salt. Lead was extracted in 1:2.5 soil: water using metal chelating exchange resin membranes. The VISUAL MINTEQ computer program was used to estimate concentrations of various soluble inorganic and organic species of Pb in the 1:2.5 soil: water extracts and chemical composition data obtained was considered as input data. Regardless of plant type, Pb bioavailability in soil amended with organic amendments was greater than in soil amended with Pb(NO3)2 salt. The soil Pb solution in sewage sludge and cow manure treatments was mainly complexed with dissolve organic carbon (Pb- DOC) and the other species of the metal in soil solution were low. A strong relationship between concentrations of soil Pb extracted by the Ca-saturated Chelex membrane with shoots and root corn Pb concentration showed that the resin membrane extraction can be used to estimate Pb phytoavailability of soil. According to the results, inorganic and organic components of organic treatments significantly affect Pb phytoavailability.