Glyphosate and nutrient retention in preferential flow pathways

GIACCIO, G. C; PEDRO LATERRA; VIRGINIA APARICIO; JOSE LUIS COSTA; MARINO PURICELLI

ECOLOGÍA AUSTRAL

ASOCIACIÓN ARGENTINA DE ECOLOGÍA

Lugar: Buenos Aires; Año: 2019 vol. 29 p. 329 - 338

0327-5477

Riparian vegetation strips (RVS) reduce surface runoff volume and retain sediments, pesticides andnutrients that are transported across them from adjacent crop-fields (CF). The ability of these strips to retainglyphosate has been demonstrated using experimental plots, but the spatial variability of that process isunknown. In this work, the influence of microtopography inside the RVS on the retention of glyphosate (andits major metabolite, AMPA), phosphorus and nitrogen were analyzed within a RVS of agricultural landscapes.Retention levels inside and outside preferential flow pathways (PFP) were compared under presence andabsence of a tree stratum. Soil glyphosate + AMPA concentration within PFP was 88-fold higher than outside.Phosphorus and nitrogen soil concentrations, clay and bulk density were also higher inside than outside thePFP. The tree stratum did not modify soil concentration of glyphosate + AMPA, phosphorus, nitrogen, claycontent, nor the morphometry of the PFP. Bulk density and clay content recorded in adjacent CF and in PFP,in addition to the high glyphosate, phosphorus and nitrogen concentrations in PFP soil, are consistent with ahydraulic connection between the CF and the PFP. These results contrast with some conclusions obtained fromexperimental studies under uniform plots and emphasize the importance of taking into account the genesisand structure of PFP in the design, evaluation and management of the filtering function of RVS.