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A Watershed Study of Glyphosate Transport in Runoff
Author(s) -
Edwards W. M.,
Triplett G. B.,
Kramer R. M.
Publication year - 1980
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1980.00472425000900040024x
Subject(s) - glyphosate , surface runoff , environmental science , watershed , agronomy , zoology , nonpoint source pollution , hydrology (agriculture) , aminomethylphosphonic acid , biology , ecology , geotechnical engineering , machine learning , computer science , engineering
Glyphosate ( N ‐[phosphonomethyl]glycine) 3 formulated as Round‐up® herbicide, 4 was applied on 0.3‐ to 3.1‐ha watersheds at rates of 1.10‐, 3.36‐, and 8.96‐kg/ha as a preseeding herbicide in the no‐tillage establishment of rescue ( Festuca arundinacea L.) and corn ( Zea mays L.). Runoff from natural rainfall following early springtime treatments was measured and analyzed to define concentration and transport of glyphosate under these conditions. The highest concentration of glyphosate (5.2 mg/liter) was found in runoff occurring 1 day after treatment at the highest rate. Glyphosate (2 µ g/liter) was detected in runoff from this watershed up to 4 months after treatment. For the lower application rates, maximum concentration of the herbicide in runoff was < 100 µ g/liter for events occurring 9–10 days after application and decreased to <2 µ g/liter within 2 months of treatment. The maximum amount of glyphosate transport by runoff was 1.85% of the amount applied, most of which occurred during a single storm on the day after application. In each of the three study years, herbicide transport in the first runoff event following treatment accounted for 99% of the total runoff transport on one watershed. Glyphosate residues in the upper 2.5 cm of treated soil decreased logarithmically with the logarithm of time; they persisted several weeks longer than in the runoff water.