pH dependence of Glyphosate adsorption on soil horizons

Abstract

Pesticides bring many problems to the environment and to human health. The first rationale for their use is increased food production. Glyphosate N-(phosphonomethyl)glycine (PMG) is a non-selective, post emergent, and broad spectrum herbicide, very well known for its extensive application in agriculture worldwide. PMG adsorption experiments were carried out in three horizons of a Typic Haplustoll soil from the Province of Santiago del Estero, Argentina. Adsorption isotherms were fitted using Freundlich and Langmuir models. The affinity constants (KF and KL), the adsorption intensity (1/n) and the maximum surface coverage (Gmax) were obtained. The results show the dependence of the parameters KL and Gmax with pH and also with the different horizons and particle size.