3.1 According to the list of standard fertilisers, this method is applicable to products containing calcium cyanamide.
3.1.1 In the absence of nitrates, the sample is subjected to direct Kjeldahl digestion.
3.1.2 In the presence of nitrates, the sample is subjected to Kjeldahl digestion after reduction with the aid of metallic iron and stannous chloride.
In both cases, the ammonia is determined according to Method 2.
Note: If analysis shows an insoluble nitrogen content of more than 0.5%, it is presumed that the fertiliser contains other forms of insoluble nitrogen not specified for fertilisers covered by the list in paragraph 2.