Glyphosate fate in soils when arriving in plant residues. (July 2016)

• Record Type: Journal Article
• Authors: Mamy, Laure; Barriuso, Enrique; Gabrielle, Benoît
• Is Part Of: Chemosphere. Volume 154(2016)
• Page Start: 425
• Page End: 433
• Publication Date: 2016-07
• Subjects: Glyphosate-tolerant crop -- Oilseed rape -- Mineralization -- Extractability -- Non-extractable (bound) residues -- AMPA; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2016.03.104
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: A significant fraction of pesticides sprayed on crops may be returned to soils via plant residues, but its fate has been little documented. The objective of this work was to study the fate of glyphosate associated to plants residues. Oilseed rape was used as model plant using two lines: a glyphosate-tolerant (GT) line and a non-GT one, considered as a crucifer weed. The effects of different fragmentation degrees and placements in soil of plant residues were tested. A control was set up by spraying glyphosate directly on the soil. The mineralization of glyphosate in soil was slower when incorporated into plant residues, and the amounts of extractable and non-extractable glyphosate residues increased. Glyphosate availability for mineralization increased when the size of plant residues decreased, and as the distribution of plant residues in soil was more homogeneous. After 80 days of soil incubation, extractable 14 C-residues mostly involved one metabolite of glyphosate (AMPA) but up to 2.6% of initial 14 C was still extracted from undecayed leaves as glyphosate. Thus, the trapping of herbicides in plant materials provided a protection against degradation, and crops residues returns may increase the persistence of glyphosate in soils. This pattern appeared more pronounced for GT crops, which accumulated more non-degraded glyphosate in their tissues. Graphical abstract: Highlights: Better insight into the fate of pesticide returned to soils via plant residues is needed. Incorporation into oilseed rape residues hampered the mineralization of glyphosate in soils. Incorporation into plant residues increased the amounts of glyphosate and of its metabolite in soils. The trapping of pesticides into plant materials increases their persistence in soils.