Interlaboratory study cen-methods for the analysis of growing media and soil improvers

For testing phytotoxicity many methods have been developed. In this experiment some methods are compared. Tests with development of cucumber cotyledons, luminescence of bacteria, growth of duckweed and root growth of germinating seeds of kohlrabi and garden cress are compared. All tests were suitable but the bioassay where development of cucumber cotyledons is determined and the luminescence of bacteria were the most practicable. The different bioassays give comparable results but they cannot always be converted directly. The different bioassays can be used when in a short time results are needed or when experience has learned that e.g. phytotoxic substances can be expected from a certain production process. For a more robust general bioassay an adapted version of ISO 11269-2 (1995) standard for testing the soil quality looks promising, although the adaptations still have to be tested.