Interaction of the herbicide glyphosate with copper in humic complexes

Glyphosate is a herbicide which is considered to be inactived in soil by bonding to clays and organic matter, possibly through metal bridges. In this paper it has been shown that copper in inner-sphere complexes with humic substances is complexed by the herbicide. After hydrolysis of the humic acid fraction with water followed by 6M HCl, the glyphosate was unable to react with copper in the humic-copper complex to form a glyphosate complex probably because the copper is more strongly bound on sites previously occupied by iron.