DISTRIBUTION OF NITROGEN IN THE BLACK SOLONETZIC AND BLACK CHERNOZEMIC SOILS OF ALBERTA
More N was brought into solution by hydrolysis with 6 N HCl from the Ah horizons of a Black Solonetz and a Black Solod than from the Ah horizon of a Black Chernozem soil of Alberta. The percentages of total N represented by the ammonium-N, amino acid-N and amino sugar-N were similar for the three soils. The proportion of soil-N present as amino acid-N and amino sugar-N decreased and that of ammonium-N increased with depth in all three profiles. The acid hydrolysis of the water-extract obtained from Ah horizon of the Black Solonetz released more (ammonium + amino acid + amino sugar)-N than did that of the Ah horizons of the other two soils. The humic acid fractions obtained from Ah horizons contained more total N than did the humic acids extracted from the B horizons of the three soils. While the proportions of N accounted for as (ammonium + amino acid + amino sugar)-N in the humic acid fractions from Ah horizons of the soils were similar, they increased in the order Chernozem > Solod > Solonetz for the B horizons. In general, there were few noteworthy differences in the amino acid distribution between the three soils or between the various horizons of the same soil. The hydrolyzates of the water-extracts of Ah horizons showed higher values for the molar distribution of threonine, serine, glycine and alanine, and lower values for aspartic acid and glutamic acid than did the corresponding hydrolyzates of the soils; the amounts of free amino acids in these extracts were very small. There was little difference in the amino acid composition of the humic acid fractions obtained from the three soils or from the different horizons of the same soil; it was, in general, similar to that of the soils. The data indicate that differences in the salt regime in the Solonetzic, Solodic and Chernozemic soils do not result in the different kinds of nitrogenous organic matter.