THE FORMS OF NITROGEN IN THE ORGANIC MATTER OF DIFFERENT HORIZONS OF SOIL PROFILES

Abstract

A study was made of the amount of amide-N (as glutamine and asparagine) in soil materials by methylating the organic material with methanolic-HCl, reducing the resulting product with LiBH 4 and determining the loss of glutamic and aspartic acids. The data obtained lend support to the hypothesis that a percentage of the ammonia-N formed on acid hydrolysis, equal or nearly equal to the sum of the glutamic acid-N + the aspartic acid-N, is derived from glutamine and asparagine. An attempt to use other methods to determine the amount of amide-N in soil materials indicated that these methods would not, in general, be reliable, although they might give acceptable results when the degree of decomposition of the organic materials was not too great (e.g., in the A 00 or A 0 horizons).