Total nitrogen

Abstract

The determination of total nitrogen in soils and other complex heterogeneous materials containing several forms of nitrogen presents many difficulties, and with soils these difficulties are increased by the inadequacy of knowledge concerning the forms of nitrogen present and by the low nitrogen content of the material under analysis. Two methods have gained general acceptance for determination of total-nitrogen: the Kjeldahl method, which is essentially a wet-oxidation procedure, and the Dumas method, which is fundamentally a dry-oxidation technique. The standard Dumas method is a time-consuming and complicated procedure, and the comparatively rapid and simple Kjeldahl method has been used almost exclusively for determination of nitrogen in soils. The Kjeldahl procedures generally employed for determination of total-nitrogen involve two steps: digestion of the sample to convert the nitrogen to ammonium; determination of the ammonium in the digest.