该方法包括在酸性介质中用铬粉将硝酸盐还原为氨，在催化剂存在下用浓硫酸消化将有机氮和尿素氮转化为硫酸铵，从碱性溶液中蒸馏氨，并吸收过量的标准体积氢氧化钠溶液。对于有机物含量超过7%的材料，不建议使用该方法。

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.