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.
On the Nutrition and Metabolism of Zooplankton II. The relationship between the marine copepod Calanus helgolandicus and particulate material in Plymouth sea water, in terms of amino acid composition
