OECD 216: Soil microorganisms (nitrogen transformation test)
Soil microorganisms: a nitrogen transformation test assesses the long-term impact of a one-time chemical exposure on the nitrogen transformation activities of soil microorganisms. Soil is treated with the test chemical and observed regularly over a 28-day period. If, after 28 days, a significant difference (>25 %) exists between nitrogen transformation activity in the test and control soils, up to 72 additional days of observation may be conducted.