The fertilising value and nitrifiability of humic materials prepared from coal (with three text-figures)

1. Humic acids and ammonium humates prepared by a patented process of gentle oxidation of coal were examined as fertilisers by laboratory nitrification experiments and pot-culture tests on four soils and by a number of field experiments on a range of soils and crops during a single season.2. In all tests the effects of ammonium humate could not be distinguished from those of ammonium sulphate of equal ammonium content. The nitrification tests and the pot cultures afforded some evidence of a slow production of nitrate or available nitrogen from the humic acid.3. In the field experiments as in the pots there was no clear evidence of any fertiliser value apart from that due to the ammonium present.