Effect of Sewage Sludge Application and Wheat (Triticum aestivum L.) Planting on Availability and Fractionation of Zinc in some Calcareous Soils

The amount of available micronutrients such as zinc (Zn) is a primary concern in treated soils with sewage sludge. This study was performed to evaluate Zn availability (DTPA-TEA، Mehlich 1 and Mehlich 3) and its fractionation in soils before and after treated with sewage sludge (1% w/w) and after wheat plantation in greenhouse conditions. The results of this study showed that mean of Zn extracted by using chemical extractants after sewage sludge application increased significant (P0. 05). The results of fractionation showed that residual Zn، exchangeable Zn، Zn associated with organic matter، Zn associated with iron-manganese oxides، and Zn associated with carbonates increased 11، 26، 94، 172، and 279% respectively. The results of mean comparison showed that different between mean of Zn fractions (except Zn associated with iron-manganese oxides) before and after planting was significant (P)