Tilted-bed Simulation of Erosion and Chemical Runoff from Agricultural Fields: II. Effects of Formulation on Atrazine Runoff1
- R. Don Wauchope2
The concentrations and loads of atrazine [6-chloro-N-ethyl-N′-(1-methylethyl)-1,3,5-triazine-2,4-diamine] in runoff water from “tilted-bed” soil trays under intense simulated rainfall were similar to losses reported in field studies. Atrazine was applied at rates of 2.7 to 3.4 kg/ha as emulsion, wettable powder, dispersible liquid, and dispersible granule formulations, on a loam soil in eight 2.2- by 1.2-m trays tilted to 1.3% slope. In simulated storms in which 3 cm of rainfall fell in 5 min and generated 0.7 cm of runoff, total atrazine losses ranged from 4 to 8% for the emulsion and dispersible-liquid applications and 9 to 12% for the dispersible-granule and wettable-powder formulations. One-fifth of the total losses occurred in the first liter of the runoff. This initial “flush” loss of atrazine in the water front resulted in concentrations up to 23 mg/L in the first runoff depending on the differing particle sizes of the spray deposits of the different atrazine formulations. The tilted-bed/rainfall simulator system appears to offer promise as an inexpensive and convenient supplement to field experiments for characterizing pesticide movement or yield in runoff and evaluating the potential of new chemicals for nonpoint source pollution.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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