90.93 Standard confirmed Mar 13, 2023
ISO
ISO/TC 134 Fertilizers, soil conditioners and beneficial substances
International Standard
65.080 Fertilizers
The method consists in reducing of nitrate to ammonia by chromium powder in acid medium, converting of organic and urea nitrogen into ammonium sulfate by digestion with concentrated sulfuric acid in the presence of a catalyst, distilling of the ammonia from an alkaline solution and absorbing in an excess of standard volumetric sodium hydroxide solution. The method is not recommended for materials containing more than 7 % of organic matter.
PUBLISHED
ISO 5315:1984
90.93
Standard confirmed
Mar 13, 2023