Preparation of study protocol

Field studies in at least two paddies where the sediment has different characteristics of pH, texture and organic carbon contents are required for registration purposes. Since especially clay content and organic carbon content affect the agrochemical behavior in sediments, it is desirable that both systems have widely different characteristics with respect to these two criteria. These paddies should have cultivation history records on type of crop, variety, and agrochemical applications for at least 5 years. 

When aimed at a single paddy field, the waterway connected with a paddy field serves as a target for a survey. Since a water intake and a drain are installed in each paddy, a major flow of water prevails from the intake to the drain. Hence, starting and ending points should be considered when water sampling is done. For the sampling of water, at least one point in the upstream of the inflow and more than one point in the downstream of the drain should be set. 

When aimed at a group of paddy fields (an area or a region), sampling points should be set at locations where all the irrigation canals come into the area and all the drainage canals go out from the area. 

For water sampling from drainage or streams, points near a drain port of a paddy field or an industrial factory, etc., should be avoided in order that water monitoring reflects the concentration of agrochemicals in the entire area rather than a point source. 

The times of sample collection for a single paddy survey are set with respect to the application time, such as just before an application, immediately after, and 1, 3, and 7 days post-application, and at longer intervals as appropriate. For an area survey of water and waterway sediments, samples are usually collected periodically over a cultivation season focusing on the application time. 

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