Relationship between distribution of charred plant residues and humus composition in chernozemic soils
2009
Nishimura, S., Yamaguchi Univ. (Japan). Faculty of Agriculture | Tani, M. | Fujitake, N. | Shindo, H.
To gain a fundamental understanding about the relationship between the distribution of charred plant residues and the humus composition in chernozemic soils, 15 soil samples were collected from Kazakhstan, Ukraine, and Hungry. Total organic C (TOC) content of whole soil ranged from 16.2 to 61.4 g C/kg whole soil, and the organic C content of the fraction (mainly charred plant residues) of less than specific gravity 1.6 g/cubic cm (CPC) varied from 0.657 to 3.96 g C/kg whole soil, except for 2 samples. The percentage contribution of the CPC to the TOC ranged from 2.l6 to 9.29% and was 4% or more in 7 out of 15 soil samples. In all soils, the amounts of Type A humic acids exceeded greatly those of fulvic acids. The CPC was highly correlated (r0.770) with the TOC, amounts of humic and fulvic acids, and the color coefficient of humic acid. The sup(13)C nuclear magnetic resonance spectra of selected humic acids showed that the relative contents of the aromatic-C were the highest among carbon species and that the aromaticity values ranged from 0.464 to 0.742. It is assumed that in the chernozemic soils, charred plant residues contribute to the formation of Type A humic acid and fulvic acid as one of the constituents of soil organic matter, as in the case of Japanese Andosols.
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