Adsorption of glyphosate and aminomethylphosphonic acid in soils

Abstract

A b s t r a c t. The results showed that glyphosate is initially adsorbed mostly in the upper 2 cm. It is than transported and adsorbed after few days in deeper soil horizons with concomitant increasing content of its metabolite aminomethylphosphonic acid. Moreover, Fe-oxides seem to be a key parameter for glyphosate and aminomethylphosphonic adsorption in soils. This study confirmed previous studies: the analysis showed lower contents of dithionite-soluble and Fe-oxides for the Chernozem, with consequently lower adsorption of glyphosate and aminomethylphosphonic as compared with the Cambisol and the Stagnosol.K e y w o r d s: adsorption, glyphosate, aminomethylphosphonic acid, soils

Decay characteristics and erosion-related transport of glyphosate in Chinese loess soil under field conditions

“…The samples of the upper 2-cm soil layer had higher glyphosate contents in both years corresponding to the applications, with the rates being more significant in the higher than the lower application (p b 0.05), probably due to the difference in the applied doses in each case, similar to the results reported by Rampazzo et al (2013). The simple exponential model was developed to describe glyphosate decay in the loess surface soil (Eq.…”

“…Bergstrom et al (2011) reported that the residues of glyphosate and AMPA were mainly detected in topsoil (0-30 cm), despite the application of glyphosate 748 d earlier, and Shushkova et al (2010) reported that 57% of the glyphosate was concentrated in the 0-10 cm soil layer after 7 d. Studies also showed that glyphosate is initially absorbed mostly in the upper 2 cm of soil rather than transported and absorbed after a few days in deeper soil horizons (Rampazzo et al, 2013) which is similar to Yang et al (2015) and our results (Tables 2 and 3). Glyphosate and AMPA content then correspondingly decreased significantly in deeper soil layers (2-10 cm) and were even below the limit of detection in some layers.…”

“…The competition between the similar adsorption sites of glyphosate and phosphates, however, has a severe impact on glyphosate binding and hence on its mobility in soils (Borggaard and Gimsing, 2008;Zhao et al, 2009). The pH and the amounts of variable charges, clay fractions, and soil organic matter also influence the adsorption capacity of glyphosate in soils, which ranges from 62 to 2751 L kg −1 (Al-Rajab et al, 2008;Albers et al, 2009;Bergstrom et al, 2011;Gimsing and Borggaard, 2002;Gimsing et al, 2004;Gjettermann et al, 2011;Rampazzo et al, 2013;Sprankle et al, 1975;StrangeHansen et al, 2004;Wang et al, 2005Wang et al, , 2006Zhao et al, 2009). The variation of adsorption capacity in soils illustrates that glyphosate mobility is variable, and the risks of transport should be taken into account, especially in soils with high phosphate contents from the excessive application of phosphorus fertilisers (Borggaard and Gimsing, 2008).…”

Occurrence of glyphosate and AMPA in an agricultural watershed from the southeastern region of Argentina

“…The soil layer (5-10 cm) from S1, evidenced an AMPA increment in post-application period, indicating probably lixiviation from the upper layer. Rampazzo et al (2013) reported migration of glyphosate and AMPA up to 10 cm of depth after 28 days (loamy soil) and 12 days (sandy soil) of the application event. The concentration of AMPA in the soil profile decreased one order of magnitude for each 5 cm of depth in all plots and sampling times, with exception of S2 in post-application period where a decrease in two orders of magnitude was observed.…”

Glyphosate sorption to soils and sediments predicted by pedotransfer functions

“…This is indicated by the primary role of CEC in controlling Kd eq and Kf variability. Indeed, several studies have highlighted the role of CEC in the strong sorption of glyphosate to soils (da Cruz et al 2007;Mcconnell and Hossner 1985;Morillo et al 1997;Xu et al 2009), although others concluded that clay and Fe ox -Al ox play an even more important role (Bergström et al 2011;Rampazzo et al 2013;Wang et al 2005). Given the high correlation between CEC and Fe oxAl ox in our sample, it is likely that the influence of the latter property was masked by that of the former.…”