ESTIMATING RUNOFF EXPORT RATIO OF PESTICIDE RESIDUE USING RICEWQ MODEL FROM PADDY FIELD

摘要

Runoff export ratio (Ratio between losses by runoff and applied amount of pesticide) of six pesticides (Diazinon, Oxadiazone, Butachlor and Chlorpyrifos-me, 2,4-d, Carbaryl) from paddy fi eld was estimated using RICEWQ model. To refl ect water management of actual farmers, water balance of experimental paddy fi eld in Hampyung, Korea was monitored. The observed rainfall, irrigation, runoff, evapotranspiration, and infi ltration in 2007 were 952, 761, 665.3, 469 and 406 mm, respectively. Hydrology submodel was calibrated with observed water balance results. Laboratory incubation test was conducted and decaying pattern of pesticide concentrations was monitored. Parameters for pesticide submodel were determined using incubation test results after calibration. RICEWQ model simulated runoff and concentrations of the pesticide with calibrated hydrologic and pesticide submodel under conventional pesticide application scenario. Runoff ratio of each pesticide was estimated based on simulated results. When application of pesticide was varied up to 7 days, runoff ratio of Butachlor, Oxadiazone, Chlorpyrifos-me, Diazinon, 2,4-d and Carbaryl varied 13.1 ~ 17.5, 1.2 ~ 1.4, 0.57 ~ 0.66,12.0 ~ 20.5 %, 21.9 ~ 28.9 %, and 12,7 ~ 14.3 % respectively. In general, the longer half-life of pesticide resulted in the higher runoff ratio.