Zinc Fertilizers

Abstract

Zinc fertilizers are commonly applied to many crops around the world. The most common sources are ZnSO4 and ZnO, but other inorganic products and sources such as chelates and natural organic complexes also are used. Industrial by-products containing Zn also are being processed and sold as Zn fertilizers. The levels of water-soluble Zn and weak acid-soluble Zn in granular Zn products give a good measure of their effectiveness for crops. Insoluble ZnNH4PO4 compounds form in ammonium phosphate fertilizers; these reaction products are not very available for crops, especially on sandy, neutral to alkaline soils under dry conditions. Zinc fertilizers are applied to soil mainly with NPK fertilizers, either by incorporating at the factory or bulk blending in granular form with other granular fertilizers. Soluble Zn fertilizers also are applied as foliar sprays to fruit and vegetable crops. Choice of Zn fertilizer depends on the intended method of application, relative agronomic effectiveness, price per unit of Zn, compatibility, and convenience in applicatior either alone or with other fertilizers.