Preparation of the Soil Sample Ready for Ecotoxicity Testing

3 Preparation of the Soil Sample Ready for Ecotoxicity Testing 

The test material is mixed with a known amount of soil and placed in a plastic box. The test is performed at room temperature with water content adjusted to a fixed value. The material is periodically inspected to verify the degree of disintegration. Under these conditions an accelerated disintegration process is expected because of the controlled environmental conditions. A sample of a reference soil, obtained in parallel with a reference material, should be used as a negative control. In outdoor tests great care must be taken to mark the area and the depth of burial. A practical system is based on plastic sheets fixed into the soil as a barrier of perimeter, used to delimitate the burial area. 

The inhabitants of the soil include the nematodes (the most numerous multicellular animals on Earth), oligochaetes (earthworms), arthropods (crustacea, arachnids, insects), and gastropods (snails). The ecotoxicity tests which have been mostly used to test the effect of biodegradable polymers on solid substrates (such as compost and soil) are the Earthworm Acute Toxicity Test, ISO 11268-1 [76] and the Daphnia (a widespread crustacean) Acute Immobilisation and Reproduction Test [77]. 

The assessment of the effects on plant growth is of most importance, for evident reasons, (i.e., for agricultural applications). The test method mostly applied is the OECD Guideline for Testing of Chemicals 208 - Terrestrial Plants, Growth Tests [78]. 

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