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Combined Effects of Constant versus Variable Intensity Simulated Rainfall and Reduced Tillage Management on Cotton Preemergence Herbicide Runoff
Author(s) -
Potter Thomas L.,
Truman Clint C.,
Strickland Timothy C.,
Bosch David D.,
Webster Theodore M.,
Franklin Dorcas H.,
Bednarz Craig W.
Publication year - 2006
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/jeq2005.0444
Subject(s) - surface runoff , environmental science , tillage , loam , runoff curve number , hydrology (agriculture) , metribuzin , intensity (physics) , metolachlor , soil science , soil water , agronomy , pesticide , weed control , atrazine , ecology , geology , geotechnical engineering , biology , physics , quantum mechanics
Pesticide runoff research relies heavily on rainfall simulation experiments. Most are conducted at a constant intensity, i.e., at a fixed rainfall rate; however, large differences in natural rainfall intensity is common. To assess implications we quantified runoff of two herbicides, fluometuron and pendimethalin, and applied preemergence after planting cotton on Tifton loamy sand. Rainfall at constant and variable intensity patterns representative of late spring thunderstorms in the Atlantic Coastal Plain region of Georgia (USA) were simulated on 6‐m 2 plots under strip‐ (ST) and conventional‐tillage (CT) management. The variable pattern produced significantly higher runoff rates of both compounds from CT but not ST plots. However, on an event‐basis, runoff totals (% applied) were not significantly different, with one exception: fluometuron runoff from CT plots. There was about 25% more fluometuron runoff with the variable versus the constant intensity pattern ( P = 0.10). Study results suggest that conduct of simulations using variable intensity storm patterns may provide more representative rainfall simulation‐based estimates of pesticide runoff and that the greatest impacts will be observed with CT. The study also found significantly more fluometuron in runoff from ST than CT plots. Further work is needed to determine whether this behavior may be generalized to other active ingredients with similar properties [low K oc (organic carbon partition coefficient) ∼100 mL g −1 ; high water solubility ∼100 mg L −1 ]. If so, it should be considered when making tillage‐specific herbicide recommendations to reduce runoff potential.