Boletín de la Sociedad Geológica Mexicana
Volumen 67, núm. 3, 2015, p. 509-516
pH dependence of Glyphosate adsorption on soil horizons
Hector R. Tévez1, Maria dos Santos Afonso2,*
1 Facultad de Ciencias Forestales, Universidad Nacional de Santiago del Estero. Avenida Belgrano Sur 1912. 4200 Santiago del Estero, Argentina.
2 INQUIMAE, Facultad de Ciencias Exactas y Naturales- Universidad de Buenos Aires. Ciudad Universitaria, Pabellón II, 3er Piso, Ciudad Autónoma de Buenos Aires, C1428EHA, Argentina.
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 (Γmax) were obtained. The results show the dependence of the parameters KL and Γmaxwith pH and also with the different horizons and particle size.
Keywords: Glyphosate, Adsorption isotherm, horizon, profile.