Zinc (Zn) is one of the most critical plant nutrients in soil, among 17 essential plant nutrients.
The activities of Zn in soil depend on different soil characteristics, parent material, climatic
conditions, and cropping systems (vegetation). The distribution of Zn decreases with an increase
in sandy soils, increasing pH or lime content with depth, mounting soil moisture regime, and
being low in organic matter. In general, the solubility of Zn is highest in soil reactions of 4.5 to
6.0 in organic soils and 5 to 7 in mineral soils. Soil reaction and organic matter level regulate the
behavior of zinc and the plant pools available. The formation of dissoluble stable organic-metal
complexes and organo-metal complexes through the organic substance plays role in the
availability of Zn. Adsorption and desorption are the critical processes in soil that regulate the
behavior of Zn in soil and act as a division between the solution and solid phases. Zinc is
released from soil minerals or added through organic and inorganic fertilizers, and equilibrium
reactions become operative between the solution and the exchangeable phase of the soil. The
application of the organic amendment will decrease the potential for leaching. The adsorption,
desorption, and equilibrium behavior of Zn in soil are affected by soil reactions, organic sources,
cation exchange capacity, clay content, and Fe/Al oxides.