Division 1.6.2 Selection and number of soils

One single soil is used. The recommended soil characteristics are as follows:

• sand content: not less than 50% and not greater than 75%;

• pH: 5.5 -7.5;

• organic carbon content: 0.5 - 1.5%;

• the microbial biomass should be measured (8)(9) and its carbon content should be at least 1 % of the total soil organic carbon.

In most cases, a soil with these characteristics represents a worst case situation, since adsorption of the test chemical is minimum and its availability to the microflora is maximum. Consequently, tests with other soils are generally unnecessary. However, in certain circumstances, e.g. where the anticipated major use of the test substance is in particular soils such as acidic forest soils, or for electrostatically charged chemicals, it may be necessary to use an additional soil.