Studies on the Carbon and Nitrogen Cycles in the Soil. VII. The Nature of the Organic Nitrogen Compounds of the Soil: “Humic” Nitrogen

Abstract

The investigations described in this paper show that:1. The nitrogen contained in purified preparations of humic acid obtained from Rothamsted soils cannot be eliminated by methods which would be expected to remove simple nitrogenous impurities.2. The distribution of the nitrogen in the products of hydrolysis of these preparations of humic acid by hydrochloric acid, as determined by the Van Slyke method, is similar to that found in the hydrolysates of proteins.3. A mixture of egg albumen and artificial humic acid from lignin resembles soil humic acid in regard to the effect of various methods of treatment on its nitrogen content. In both cases, the greater part of the nitrogen is not removed by the action of proteoclastic enzymes.