Knowledge of the chemical forms of Zn in the soil and the relationships with soil available concentrations are important for predicting its behavior. This work aimed to study the influence of zinc on the desorption, extraction and fractioning of Zn in samples from six Oxisols. The soil samples, with and without lime application, were kept incubated for 30 days after receiving Zn doses (0.0, 20, and 40 mg dm-3). After incubation, the micronutrient was extracted with Mehlich-1, Mehlich-3, DTPA and EDTA. Additionally, the samples were fractionated for Zn determination in the fractions: exchangeable, organic matter, manganese oxides, amorphous iron oxides, crystalline iron oxides, and residual fraction, as well as the total concentrations of the micronutrient. The micronutrient desorption was evaluated by successive extractions with cation exchange resin. It was concluded that, without liming, the application of the Zn doses to the soil resulted in retention of Zn mainly in the exchangeable and organic matter fractions. In general, liming reduced the exchangeable contents and increased organic matter, amorphous and crystalline iron, and manganese oxide fractions. Without liming, Zn in the exchangeable fraction was highly correlated with all extractors. With liming, all extractors presented high correlation with Zn in the organic matter fraction. Without liming, Zn lability in the fractions decreased in the order: Ex = OM > MnOx > AFeOx >> CFeOx, for EDTA. Mehlich-1, and Mehlich-3, presented best correlations with the total desorbed zinc amounts, while liming caused absence of Zn desorption.
Micronutrients; liming; soil analysis