A Simple Digestion Procedure for Estimation of Total Nitrogen in Soils and Sediments

Abstract A simple and convenient digestion procedure for total N analysis of soils and sediments is described. The digestion is carried out in pyrex Folin‐Wu tubes heated in an aluminum block placed on a hot plate. Samples up to 1 g in size may be used and a digestion time of 3 hours after clearing is adequate. The proposed and conventional semimicro‐Kjeldahl methods gave essentially the same values for total N in a wide variety of soils and sediments. The precision of the proposed method was almost as good as those reported for other semimicro‐Kjeldahl methods. The tube digestion method allows simultaneous digestion of 60 samples in a relatively inexpensive and maintenance‐free aluminum heating block, which occupies a minimum of laboratory space and appears applicable for routine determination of total N in soils having diverse properties.