Glyphosate mobility in piedmont soils of the Australes range in the south of Buenos Aires Province

Abstract

The increase in agricultural production is leading to an intensive use of chemical products to improve plant growth. This study of glyphosate soil adsorption took place in an experimental parcel of an agricultural sector of the Buenos Aires province. In this region the product is currently applied in areas of direct sowing and in very small doses. The tests in batch allowed the determination of the partition coefficient Kd, which relates the concentration of glyphosate in the water phase to the adsorbed one in the soil. The Kd coefficient was standardized according to the content of organic matter (Koc), and optimized using models based on the isotherm of Freundlich. The greater degree of adsorption of the glyphosate occurs at surface level and decreases with depth, owing more to variations in the structure and chemical composition of the clay sediments than to the effect of the organic matter. There is a very high adsorption of the glyphosate in the ground so that it would fall into the category of non leachable. This characteristic makes it potentially a little polluting agent, provided conditions of preferential flow that could significantly increase its mobility were not generated.