Full Description ADOPTED_FROM:EN ISO 17155:2020 This International Standard specifies a test method for determining the activity of active aerobic, eterotrophic microbial biomass in soils. This method is applicable to the monitoring of soil quality and to the evaluation of the ecotoxic potential of soils and soil materials. It is also applicable for soils sampled along contamination gradients in the field and to soils that are contaminated experimentally in the field or in the laboratory.