As recommended by the soil microbial
tests workgroup at the workshop on standardised test methods for soils (Fairbrother
et al. 1999), toxicity in natural soils containing indigenous
microbial communities was examined.
We selected three control subsoils representative of
metal-contaminated sites in New Zealand. However, we were unable
to obtain satisfactory and reproducible dose-response relationships
between nitrogen mineralisation and exposure to metals using this
microbial test method, in all except one test.
We are therefore unable to report the ecotoxicity
values for micro-organisms in New Zealand soils.