Rock to Crop: Micronutrients, Metals, and More.

Micronutrient fertilizer manufacture differs significantly from the manufacture of nitrogen, phosphorus, and potassium.  Macronutrient raw materials are harvested directly from naturally occurring sources – nitrogen from the atmosphere, phosphorus and potassium from various ore deposits.  Most micronutrient fertilizers are manufactured from by-products of other industries.  Metals such as zinc, manganese, copper, and iron are valuable resources produced by various metal manufacturing and other industrial processes.  These by-products, generally metal oxides,  are the primary raw materials for micronutrient fertilizers.  The metal micronutrient fertilizers may be manufactured by one of two basic processes.  One is a complete dissolution in concentrated acids, usually sulfuric acid, to form metal liquor which is then purified and granulated.  The other process is a partial reaction with acid in a granulation process.  Boron is the notable exception among the micronutrients.  Various boron ores are mined and purified to make soluble boron fertilizers.  There are wide differences in micronutrient raw material sources that directly affect the process chosen and the final product produced.  The raw materials, reactions, and processes also directly influence cost of production and quality of the final product.  Because of this there may be large differences in the variety of products available from which a user may choose.  Product quality differences may not always be indicated on the product label so the user is advised to be informed as to what these differences may be, and how they affect product cost, agronomic performance, and ultimate product value.  Micronutrient manufacturing recaptures valuable natural resources and converts them to usable plant nutrient sources that are essential to producing high yields of quality crops.