ALBERT

Description: not available

Description: The nitrogenous products formed by 6 N HCl hydrolysis of a variety of peats including a cultivated mesic profile, a virgin humic profile, a sedge, a woody and a sphagnum fibric peat were studied. Peat fractions separated according to particle size, woody and herbaceous materials isolated from a peat sample, and Typha and Carex plants growing on peat soils were also analyzed. Of the two profiles examined, the cultivated mesic peat showed significant quantitative changes in the content of individual amino acids throughout the profile. Also the amino sugar and amino acid N increased to a maximum, then decreased. On the other hand, the virgin humic peat profile exhibited random variations in the content of the individual amino acids and in the amount of amino acid N. Of the other peats examined, the fibric sphagnum had the highest percentage of amino acid N. Among the separates, the 100- to 200-mesh material had the highest proportion of amino acid N. The amino acid composition of the plant remains from the peat was similar to that of the peat from which it was isolated. The amino acid composition of the Typha and Carex plants was different from that of peat in that 75% of their total N content could be accounted for on the basis of amino acid, amide and amino sugar N. The amounts of hydroxyproline and the amino sugars in peats vary more than that of the amino compounds. In contrast to inorganic soils, which tend to have a similar amino acid composition, these limited data suggest that the amino acid and amino sugar contents of peats may be characteristic of individual bogs.

Description: The effect of freezing and duration of storage of frozen soil on free amino acids and sugars was evaluated. Freezing caused a marked increase in the total amount of free amino acids and sugars extracted. The level of free amino acids and sugars, in frozen soil, remained fairly constant up to a storage period of 6 weeks, after which a prominent decrease occurred. Essentially there was no difference between single freeze-thaw and multiple freeze-thaw cycles. In general, soil respiration and dehydrogenase activity paralleled the level of extractable free amino acids and sugars.

Description: A system of separating asparagine, glutamine and citrulline from each other and from the other common amino acids, using lithium buffers and the Technicon amino acid analyzer and C2 resin in a 0.63 × 75-cm column, is described. The column was operated with a buffer flow rate of 37 ml/hour at 30 °C for the first 70 min, then at 50 °C. The buffer was 0.067 M in lithium citrate and adjusted to a pH of 2.80; 2% isopropanol was added to improve the separation of threonine and serine. The analysis was complete through citrulline in 4 hours. If a second buffer, pH 4.15, 0.25 N in lithium was added after 3.5 hours, most of the common acidic and neutral amino acids found in soil extracts were separated in 6 hours. Some data on the determination of asparagine and glutamine by amide hydrolysis is included.

Description: Forms of nitrogen in 92 samples were measured in a study designed to determine the similarities and differences in the nitrogen distribution in various horizons of a wide range of Canadian soils. The samples, representing all of the nine soil orders, were chosen from different climate and vegetation zones. Some peat soils were analyzed also. The data were first grouped according to the nitrogen content of the samples, but the amino acid composition of the soil "protein" did not appear to be related to this. The data were then grouped according to LFH, A, B and C horizons and also according to the Ah, Ap, Ae, Bhf, Bh, Bm and Bt layers. Again, few significant differences in the amino acid composition could be found. Data for the average amino acid composition and standard deviations for 92 mineral soils, 6 LFH and 2 ’O’ horizons of these and 18 peat soils were calculated. Since the analytical and sampling errors appear to be relatively small and would not account for all the variation between samples, there appeared to be real but relatively small and random differences in the amino acid composition of the different samples. The data for the individual soils supported this conclusion; for instance, some samples had very small or barely detectable amounts of hydroxyproline, while with other soils it made up 1–2% of the amino acid nitrogen. The amino sugar composition was more variable and the glucosamine/galactosamine ratio varied from 2:1 for the LFH horizons to 1:1 for the peat soils. In general, however, the soil "protein", which is probably largely the result of microbial degradation and synthesis, is remarkably similar to its amino acid composition. Amino acid nitrogen made up over half of the total nitrogen of the LFH and O horizons. This underestimated the "protein" nitrogen, since there is probably some amide nitrogen (about 5%) not included. In the mineral soils probably about 40% was "protein" nitrogen (including aminde), 5% was amino sugar nitrogen, 18% hydrolyzable unidentified nitrogen and 13.5% was insoluble in the acid used for hydrolysis. Clay-fixed ammonium made up 17% of the total nitrogen and much of the hydrolyzable ammonium came from this.

Description: The free amino acids and the total ninhydrin-reacting material found in the rhizosphere of plants grown under field conditions were compared with those in the nonrhizosphere soil and with root extracts. Water, 20% ethanol and carbon tetrachloride-water were used as extractants. While the last two removed more amino acids than the water, this was probably the result of partial decomposition of the cellular material of the soil. The use of water as an extractant should give a better measure of the amount of amino acids in the soil under natural conditions. The rhizosphere contained greater quantities of amino acids than the soil from outside this zone. In general, the most prominent amino acids were aspartic acid, threonine, serine, glutamic acid, glycine and alanine; asparagine, glutamine and citrulline were also present. The amino acid content of the rhizosphere varied with the plant. Although root extracts contained very large quantities of amino acids, comparison of these extracts with the rhizosphere showed distinct differences in amino acid ratios, suggesting that the amino acids in the rhizosphere were not primarily the result of root-debris autolysis during the extraction procedure.