Glyphosate and phosphorus leaching and residues in boreal sandy soil

Abstract

Glyphosate [(N-(phosphonomethyl)glycine)] is a widely used herbicide and it is known to compete for the same sorption sites in soil as phosphorus. Persistence and losses of glyphosate were monitored in a field with low phosphorus status and possible correlation between glyphosate and phosphorus leaching losses was studied. Glyphosate and its metabolite AMPA (aminomethyl phosphonic acid) residues in soil samples were analysed after a single application in autumn. Twenty months after the application the residues of glyphosate and AMPA in the topsoil (0-25 cm) corresponded to 19% and 48%, respectively, of the applied amount of glyphosate, and traces of glyphosate and AMPA residues were detected in deeper soil layers (below 35 cm). These results indicate rather long persistence for glyphosate in boreal soils. Surface runoff and subsurface drainflow were collected continuously all year round for 20 months and analysed for glyphosate, AMPA, dissolved phosphate, total phosphorus and total suspended solids.The glyphosate concentrations in the surface runoff water were highest, with 99% of the total leaching losses obtained, during the periods of snow melting and soil thawing in the first winter following the autumn application. The total leaching of glyphosate was 5.12 g ha −1 and that of AMPA 0.48 g ha −1 , corresponding to about 0.51% and 0.07%, respectively, of the applied amount of glyphosate. No residues of glyphosate and AMPA were detected in the subsurface drainflow. The correlations between concentrations of glyphosate and dissolved orthophosphate as well as glyphosate and total phosphorus in surface runoff were significant (p<0.01).

Distribution of glyphosate and aminomethylphosphonic acid (AMPA) in agricultural topsoils of the European Union

“…Here GlyBH are usually applied one (cereals and oilseeds) to three times a year (orchard crops and vines), at recommended rates between 0.72 and 2.88 kg glyphosate ha −1 per treatment, and at a maximum annual application rate of 4.32 kg glyphosate ha −1 (EFSA, 2013(EFSA, , 2015. Numerous laboratory and field studies have been performed to investigate glyphosate and/or AMPA behavior in more detail, especially their transport to the aquatic environment (Al-Rajab and Hakami, 2014;Borggaard and Gimsing, 2008;Daouk et al, 2013;Laitinen et al, 2006Laitinen et al, , 2009 indicating some recognition and concern that these substances can move towards surface waters. At the same time, glyphosate and AMPA are only sporadically detected in deep groundwater systems and at low concentrations (Battaglin et al, 2014;Horth, 2012;Poiger et al, 2017) indicating that the leaching of these compounds is generally unlikely and probably negligible.…”

“…In fact, despite some recent studies on the distribution of glyphosate and AMPA in soils from Argentina (e.g., Aparicio et al, 2013;Lupi et al, 2015;Primost et al, 2017), U.S.A. (e.g., Battaglin et al, 2014;Scribner et al, 2007) or Australia (e.g., Todorovic et al, 2013), in Europe, where the approval for GlyBH use will be decided by the end of 2017, information on occurrence and levels of these substances in soil is still very limited and out of date (Grunewald et al, 2001;Laitinen et al, 2006Laitinen et al, , 2007Laitinen et al, , 2009. The European long term use of GlyBH, as the most sold herbicide in Europe, urgently require monitoring of residues in agricultural soils.…”

Short-term transport of glyphosate with erosion in Chinese loess soil — A flume experiment

“…Leaching occurs after short heavy rains, attributed to an increase in the probability of leaching through soil macropores, especially in unstructured soils (Gjettermann et al, 2009;Kjaer et al, 2005;McGechan, 2002;Stone and Wilson, 2006;Styczen et al, 2011;Vinten et al, 1983). Based on 28 months of field monitoring, 99% of the lost glyphosate (5.12 g ha −1 ) was found in the runoff, and glyphosate and AMPA accounted for 0.51 and 0.07%, respectively, of the applied glyphosate (Laitinen et al, 2009). Limited amounts of glyphosate and AMPA are found in leachates and runoff, but the potential risk of contamination in ground/surface water is often not considered, especially by suspended particles (Ruiz-Toledo et al, 2014).…”

Glyphosate biodegradation and potential soil bioremediation by Bacillus subtilis strain Bs-15

“…Furthermore, these methods allow glyphosate to be quantified at low levels in natural samples. While glyphosate applied in bioremediation is typically applied to soils in the form of aqueous solutions at approximately 0.03 M (Candela et al, 2010) or higher (Laitinen et al, 2009), these high concentrations are also environmentally relevant. Any investigation of glyphosate should address these high concentrations.…”