Available and potentially available zinc in arable black earths (gleyic chernozems) under conventional soil management

Based on a seven step sequential extraction procedure, available and potentially available fractions of zinc in agricultural soils classified to black earths (gleyic chernozems) being under conventional soil management were separated, it was found that zinc is present mostly in non available fractions and the content of labile zinc is scant. The total contents of Zn ranged from 22.7 to 221.0 mg/kg. The exchangeable Zn was low accounting for less than 7% of the total in most soils. Zinc availability is restricted due to fixation of metal to soil components: iron oxides and organic matter. Zinc was also found in significant amounts in residual fraction, which refers to metal tightly bound in crystal lattice of primary minerals. The study shows that in majority of analyzed soils, available zinc is below the deficit limit. It is necessary to recognize the scale of the problem due to possible application of Zn fertilizer.