EXTRACTION OF NITROGEN-CONTAINING ORGANIC MATTER FRACTIONS FROM A BROWN FOREST SOIL

Abstract

After treatment with hydrofluoric acid, the soil was successively extracted with pyrophosphate, 0.03 N NaOH, 0.2 M acetylacetone and 0.5 N NaOH. Other samples of the soil were extracted with 0.2 M acetylacetone, then with a chelating resin. The extracts were dialyzed to remove soluble inorganic and low molecular weight organic material, and freeze-dried. Except for the pyrophosphate extract, the amount of ash remaining in the extracts was high. More nitrogen was lost in the various dialysates than was recovered in the dried extracts. The percent recovery of amino acid nitrogen in the pyrophosphate + 0.03 N NaOH extracts and their residue was higher than that of ammonia nitrogen, while that of the hexosamine nitrogen was intermediate. The amino acid distribution was similar in the soil, the extracts and the residues. However, the amino acid nitrogen as a percentage of the total nitrogen was, in general, higher in the extracts while the percentage of hexosamine was lower. Except for the 0.5 N NaOH, the extractants removed a small proportion of the glucosamine. The alkali extractions may have decomposed some of the asparagine and glutamine.