Copper Cycle Harvest Plant residue Hydrous oxides & carbonates Cu additives in feed Copper Cycle Harvest Plant residue Hydrous oxides & carbonates Parent material Soil Solution: Cu2+ and soluble Cu Fertilizers, fungicides, atmospheric deposition Microbes Organo-metallic complexes Microbial residue Weathering Adsorption pH > 7 Desorption pH < 6 Precipitation Dissolution Complextion pH > 6 Release pH <6 Clay & OM Soluble Cu2+ & chelated Cu (under extreme conditions) Leaching Toxic to sheep when Cu: Mo ratio > 10:1 Sewage sludge Animal waste Mining