抄録
The runoff loadings and characteristics of pesticides applied to paddy fields after transplanting of rice plant were estimated by means of analysis of pesticides in drainage river water in weekly and at the rainfall events.
The largest loadings of herbicides were found between one and two weeks after transplanting of rice plant. On the other hand, the largest loadings of insecticides were found at about ten days later than that of herbicides.
The runoff loadings of herbicides during one rainfall event ranged 20 to 25% of total runoff amounts. Therefore, the runoff investigation of pesticides in river water at and after the rainfall are very important for estimation of pesticides runoff from agricultural fields to drainage river.
The runoff characteristics of insecticides and herbicides were differed, and it was recognized that the runoff loadings of insecticides were decreased more rapidly than herbicides at the rainfall event.
The runoff rates of pesticides were ranged from 25% for fenobucarb to 0.02% for fenitrothion.
From this results concerned in rainfall event, the runoff rates of pesticides from agricultural fields to river were more higher than that of the previous literature.
