The determination of nitrogen in soils by rapid high‐temperature Kjeldahl digestion and autoanalysis

Abstract

Kjeldahl digestion time can be reduced to 10 min after clearing by using a phosphoric - sulphuric acid mixture. The digest is analyzed for N by autoanalysis incorporating a distillation step. Agreement with a standard 5-h digestion procedure is satisfactory and acceptable level of precision is obtained. The method may be readily adapted to include NO2 and NO3 and recovery of added NO3 is satisfactory.