The mobility of thiobencarb and fipronil in two flooded rice-growing soils.
The mobility of the rice pesticides thiobencarb (S-[(4-chlorophenyl) methyl] diethylcarbamothioate) and fipronil ([5-amino-3-cyano-1-[2,6-dichloro-4-(trifluoromethyl)phenyl]-4-[(trifluoromethyl)sulfinyl]pyrazole) were investigated in the glasshouse under flooded conditions using two Australian rice-growing soils. When using leakage rates of 10 mm day(-1), less than 20% of applied thiobencarb and fipronil remained in the water column after 10 days due to rapid transfer to the soil phase. Up to 70% and 65% of the applied thiobencarb and fipronil, respectively, were recovered from the 0-1 cm layer of soils. Only 5-7% of each pesticide was recovered from the 1-2 cm layer, and less than 2% was recovered from each 1 cm layer in the 2-10 cm region of the soils. Analysis of the water leaking from the base of the soil cores showed between 5-10% of the applied thiobencarb and between 10-20% of the applied fipronil leaching from the soil cores. The high levels of pesticide in the effluent was attributed to preferential flow of pesticide-laden water via soil macropores resulting from the wetting and drying process, worm holes and root channels.
Doran
Gregory
G
Cooperative Research Centre for Sustainable Rice Production, Charles Sturt University, Wagga Wagga, Australia. gdoran@csu.edu.au
Eberbach
Philip
P
Helliwell
Stuart
S
D004190:Disasters; D012275:Oryza / Q000254:growth & development*; D010575:Pesticides / Q000032:analysis* / Q000633:toxicity; D018517:Plant Roots / Q000254:growth & development; D011720:Pyrazoles / Q000032:analysis* / Q000633:toxicity; D012989:Soil Pollutants / Q000032:analysis* / Q000737:chemistry / Q000633:toxicity; D013859:Thiocarbamates / Q000032:analysis* / Q000633:toxicity; D013997:Time Factors; D014872:Water Movements; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000633:toxicity
D010575:Pesticides; D011720:Pyrazoles; D012989:Soil Pollutants; D013859:Thiocarbamates; D014874:Water Pollutants, Chemical; C037925:benthiocarb; C082360:fipronil