Infiltration and Adsorption of Dissolved Atrazine and Atrazine Metabolites in Buffalograss Filter Strips
- L. J. Krutz *a,
- S. A. Sensemana,
- M. C. Dozierb,
- D. W. Hoffmanc and
- D. P. Tierneyd
- a Dep. of Soil and Crop Sci., Texas Agric. Exp. Stn., Texas A&M Univ., College Station, TX 77843
b Dep. of Soil and Crop Sci., Texas Cooperative Extension, Texas A&M Univ., College Station, TX 77843
c Blackland Res. Center, Texas Agric. Exp. Stn., Temple, TX
d Environ. Stewardship and Regulatory Policy, Syngenta Crop Protection, P.O. Box 18300, Greensboro, NC
Vegetated filter strips (VFS) potentially reduce the off-site movement of herbicides from adjacent agricultural fields by increasing herbicide mass infiltrated (M inf) and mass adsorbed (M as) compared with bare field soil. However, there are conflicting reports in the literature concerning the contribution of M as to the VFS herbicide trapping efficiency (TE). Moreover, no study has evaluated TE among atrazine (6-chloro-N-ethyl-N′-isopropyl-[1,3,5]triazine-2,4-diamine) and atrazine metabolites. This study was conducted to compare TE, M inf, and M as among atrazine, diaminoatrazine (DA, 6-chloro-[1,3,5]triazine-2,4-diamine), deisopropylatrazine (DIA, 6-chloro-N-ethyl-[1,3,5]triazine-2,4-diamine), desethylatrazine (DEA, 6-chloro-N-isopropyl-[1,3,5]triazine-2,4-diamine), and hydroxyatrazine (HA, 6-hydroxy-N-ethyl-N′-isopropyl-[1,3,5]triazine-2,4-diamine) in a buffalograss VFS. Runoff was applied as a point source upslope of a 1- × 3-m microwatershed plot at a rate of 750 L h−1 The point source was fortified at 0.1 μg mL−1 atrazine, DA, DIA, DEA, and HA. After crossing the length of the plot, water samples were collected at 5-min intervals. Water samples were extracted by solid phase extraction and analyzed by high performance liquid chromatography (HPLC) photodiode array detection. During the 60-min simulation, TE was significantly greater for atrazine (22.2%) compared with atrazine metabolites (19.0%). Approximately 67 and 33% of the TE was attributed to M inf and M as, respectively. These results demonstrate that herbicide adsorption to the VFS grass, grass thatch, and/or soil surface is an important retention mechanism, especially under saturated conditions. Values for M as were significantly higher for atrazine compared with atrazine's metabolites. The M as data indicate that atrazine was preferentially retained by the VFS grass, grass thatch, and/or soil surface compared with atrazine's metabolites.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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