title: Persistence of glyphosate and aminomethylphosphonic acid in loess soil under different combinations of temperature, soil moisture and light/darkness.
abstract: The dissipation kinetics of glyphosate and its metabolite aminomethylphosphonic acid (AMPA) were studied in loess soil, under biotic and abiotic conditions, as affected by temperature, soil moisture (SM) and light/darkness. Nonsterile and sterile soil samples were spiked with 16mgkg-1of glyphosate, subjected to three SM contents (20% WHC, 60% WHC, saturation), and incubated for 30days at 5°C and 30°C, under dark and light regimes. Glyphosate and AMPA dissipation kinetics were fit to single-first-order (SFO) or first-order-multicompartment (FOMC) models, per treatment combination. AMPA kinetic model included both the formation and decline phases. Glyphosate dissipation kinetics followed SFO at 5°C, but FOMC at 30°C. AMPA followed SFO dissipation kinetics for all treatments. Glyphosate and AMPA dissipation occurred mostly by microbial activity. Abiotic processes played a negligible role for both compounds. Under biotic conditions, glyphosate dissipation and AMPA formation/dissipation were primarily affected by temperature, but also by SM. Light regimes didn't play a significant role. Glyphosate DT50 varied between 1.5 and 53.5days, while its DT90 varied between 8.0 and 280days, depending on the treatment. AMPA persisted longer in soil than glyphosate, with its DT50 at 30°C ranging between 26.4 and 44.5days, and its DT90 between 87.8 and 148days. The shortest DT50/DT90 values for both compounds occurred at 30°C and under optimal/saturated moisture conditions, while the largest occurred at 5°C and reaching drought stress conditions. Based on these results, we conclude that glyphosate and AMPA dissipate rapidly under warm and rainy climate conditions. However, repeated glyphosate applications in fallows or winter crops in countries where cold and dry winters normally occur could lead to on-site soil pollution, with consequent potential risks to the environment and human health. To our knowledge, this study is the first evaluating the combined effect of temperature, soil moisture and light/dark conditions on AMPA formation/dissipation kinetics and behaviour.
authors: Soil Physics and Land Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen, the Netherlands. Electronic address: celia.martinsbento@wur.nl.
authors: Célia P M
authors: CPM
authors: Bento
authors: Soil Physics and Land Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen, the Netherlands; Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074, China.
authors: Xiaomei
authors: X
authors: Yang
authors: Biometris, Wageningen University, PO Box 100, 6700 AC Wageningen, the Netherlands.
authors: Gerrit
authors: G
authors: Gort
authors: State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau of Northwest A&F University, Yangling, 712100 Shaanxi, China; Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Education, Yangling, 712100 Shaanxi, China.
authors: Sha
authors: S
authors: Xue
authors: RIKILT - Wageningen UR, P.O. Box 230, 6700 AE Wageningen, the Netherlands.
authors: Ruud
authors: R
authors: van Dam
authors: RIKILT - Wageningen UR, P.O. Box 230, 6700 AE Wageningen, the Netherlands.
authors: Paul
authors: P
authors: Zomer
authors: RIKILT - Wageningen UR, P.O. Box 230, 6700 AE Wageningen, the Netherlands.
authors: Hans G J
authors: HGJ
authors: Mol
authors: Soil Physics and Land Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen, the Netherlands.
authors: Coen J
authors: CJ
authors: Ritsema
authors: Soil Physics and Land Management, Wageningen University, P.O. Box 47, 6700 AA Wageningen, the Netherlands; Institute of Crop Science and Resources Conservation (INRES), University of Bonn, 53115 Bonn, Germany.
authors: Violette
authors: V
authors: Geissen
mesh_terms: D003624:Darkness; D005998:Glycine / Q000031:analogs & derivatives* / Q000032:analysis; D006540:Herbicides; D007555:Isoxazoles / Q000032:analysis*; D007700:Kinetics; D009426:Netherlands; D012987:Soil / Q000737:chemistry*; D012989:Soil Pollutants / Q000032:analysis*; D013696:Temperature; D013777:Tetrazoles / Q000032:analysis*; D000097797:Glyphosate
chemical_list: D005998:Glycine; D006540:Herbicides; D007555:Isoxazoles; D012987:Soil; D012989:Soil Pollutants; D013777:Tetrazoles; D000097797:Glyphosate; C418233:2-amino-3-(3-hydrox-5(2-methyl-2H-tetrazol-5-yl)isoxazol-4-yl)propionic acid
keywords: AMPA; Aminomethylphosphonic acid; Dissipation; Glyphosate; Kinetic models; Loess soil