AMINO ACIDS PRESENT IN HUMIC ACIDS FROM SOILS UNDER DIFFERENT CULTIVATIONS

摘要

The composition of bound amino acids in humic acids (HA) prepared from two kinds of soils was investigated: one from a meadow and another from a plowed area. The sample from the plowed area contained a 7% higher concentration of total bound amino acids as compared to that of the meadow. In both samples, the amino acids having a neutral net charge at pH 7 showed the highest concentrations. 'Basic' amino acids with a positive pH 7 net charge, on the other hand, had the lowest concentrations. In both HA samples, glutamic acid, glycine, alanine, and valine dominated. The lysine and β-alanine concentrations were higher in the meadow sample indicating a higher microbial biomass, since these two amino acids are typical constituents of the bacterial cell walls.