Bioavailability of the NH-N Fraction

A comparison of the mean amino acid composition of the soils with those of algae, bacteria, fungi, and yeasts showed the greatest similarity to that of bacteria. [4] This suggests, perhaps not too surprisingly, a major role for microorganisms in the synthesis in the soil of amino acids, peptides and proteins from plant and animal residues, and also explains the relatively uniform amino acid composition in different soils. 

To establish whether refluxing with hot 6M HC1 for 24 h hydrolyzed all proteinaceous materials in soils, Griffith et al. [5] hydrolyzed a number of soils first with hot 6M HC1, and subsequently hydrolyzed separate samples of add-treated residues with either 0.2 M Ba(OH)2 or 2.5 M NaOH under reflux. The results obtained showed that hot 6 M HC1 released almost all of the amino acids in the soils in 24 h. 

To find out whether the N in NH-N fractions of soils was bioavailable, NH-N fractions isolated from several soils were incubated with a soil rich in day minerals, a sandy soil, and a pure sand. [8] Most of the N in the NH-N fractions was found to be 

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