The method described in this Test Guideline is designed for evaluating aerobic and anaerobic transformation of chemicals in soil. The experiments are performed to determine the rate of transformation of the test substance, and the nature and rates of formation and decline of transformation products, to which plants and soil organisms may be exposed.
About 50 to 200 g soil samples (a sandy loam or silty loam or loam or loamy sand) are treated with the test substance and incubated in the dark, in biometer-type flasks or in flow-through systems under controlled laboratory conditions. The treatment rate should correspond to the highest application rate of a crop protection product recommended in the use instructions. Also untreated soil samples are incubated under test conditions. These samples are used for biomass measurements during and at the end of the studies. The rate and pathway studies should normally not exceed 120 days. Duplicate incubation flasks are removed at appropriate time intervals and the soil samples extracted with appropriate solvents, of different polarity, and analysed for the test substance and/or transformation products. Volatile products are also collected for analysis using appropriate adsorption devices. Using 14C-labelled material, the various mineralisation rates of the test substance can be measured by trapping evolved 14CO2 and a mass balance, including the formation of soil bound residues, can be established.