Evaluate the chemical forms of zinc in the soil solutions of Vertisols used for cereal cropping.

• Soil solutions were obtained by a centrifugation method from 14 unfertilised and fertilised Vertisols.
• The soil solutions were analysed for all major cations and anions and organic carbon zinc in the soil solution exists mainly as free zinc2+ ions in these soils.
• Complexation of total soluble zinc by organic and inorganic ligands constituted 40% and 50%, respectively, of total soluble zinc in fertilised and unfertilised soil solutions.
• The organo-zinc complexes constituted 60-75% of the total inorganic Zn complexes.
• The Zn complexes with Sulphate and  hydroxide ion were less than 5% each of the total inorganic species in unfertilised soils; Zinc sulphate complexes were more common in fertilised soils.