Field soil dissipation studies

The four main phases involved in a field soil dissipation study are (I) planning and design phase, (II) field-conduct phase, (III) sample processing/analysis phase, and (IV) data handling/reporting phase. Each phase is vitally linked to the next and each is critical to study success. Results from an otherwise perfectly executed study may be made useless by uneven test substance application or improper sampling, sample handling, and/or analytical techniques. Each of these phases is discussed below. 

Figure 1 Inter-related factors affecting the design of terrestrial field soil dissipation studies...

The time of year in which a pesticide is applied significantly affects its dissipation rate due to temperature, moisture, and solar-irradiance effects on abiotic and biotic dissipation processes. For example, dissipation rates for agrochemical applications made in the springtime are normally greater than those observed for fall (autumn) applications. Thus, the timing of agrochemical applications made in field soil dissipation studies should closely match those occurring under acmal-use conditions. 

At this stage in planning, the essential study design information listed below should be determined and a written study plan (i.e., protocol) including these key study details prepared. A formal, pre-approved study plan is required for field soil dissipation studies conducted under Good Laboratory Practice (GLP). A written study plan for non-GLP studies is highly recommended since the document serves as valuable guidance for study personnel. 

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