Zinc speciation in soil solution of selected Poland's agricultural soils

The influence of soil properties (pH, organic carbon content, soil texture, content of available zinc (Zn)) on the percentage share of the various forms of Zn in the soil solution of 62 arable soils of Poland were investigated. The soil solution was obtained following the vacuum displacement method. Speciation of zinc ions (Zn2+) was determined with MINTEQA2 for Windows software. The investigation showed that the concentration of active Zn2+ in the soil solution and related Zn bioavailability for the most part relies upon soil reaction when compared with other investigated physical and chemical soil properties. The effects of soil texture, and above all those of organic matter contents in soil, are significantly lesser. The results of speciation analysis showed that apart from physical and chemical soil properties active Zn2+ are the main forms of Zn occurring in the soil solution. Depending on soil properties these ions add up to from 60% to almost 80% of all Zn forms in the soil solution. Zinc forms can be arranged with regard to their percentage share in the soil solution as follows: Zn-DOC > ZnCO3 > ZnCl+ > ZnHCO3+ > ZnOH+.