Tracking movement dynamic of fenitrothion and thiobencarb in rice paddy using a field lysimeters at different levels of soil depth

In this study, the movement dynamic of fenitrothion (50% EC) and thiobencarb (50% EC) was investigated using the field lysimeter in the presence of rice plant at four different levels of soil depth. Iodide was used as an indicator of the mobility of these pesticides through the soil in the field lysimeter. Iodide was detected in the leachates collected at level 1 and 2 only, the concentration of iodide collected from level 2 was more than those collected from level 1. The highest breakthrough curve for fenitrothion or thiobencarb was produced from the level 4 (deep level) followed by level 3 while the breakthrough curve of level 1 was the lowest peak. Significant differences were observed among the cumulative amounts of fenitrothion or thiobencarb collected from different depth levels. The pesticide residues in the leachates increase with the depth of soil profile increase. The cumulative amounts of the two tested pesticides were compatible with the concentration of treatments, and were higher in high-treatment (50 μg/g soil) compared with that in low-treatment (25 μg/g soil). Our results obtained leaching of thiobencarb was slightly higher than the leaching of fenitrothion. These results are useful in understanding the movement of pesticides and agrochemicals in the agricultural environment.