Fractionation of humus and optical properties of humic acids originating from different soil types
2006
Ľubica Pospíšilová | Naděžda Fasurová | Lubomír Jurica
Assesment of soil organic matter quality is one of the urgent problems of contemporary agriculture. Determination of humic acids (HAs) optical properties using spectroscopic techniques could be a reliable step for this evaluation. We followed differences in the functional groups of HAs preparations and showed correlation between optical indexes and fractional composition of humus. UV-VIS and SFS spectral lines and indexes were measured in mixture 0.1M pyrophosphate sodium solution and 0,1M NaOH, after filtration and appropriate dilution. Differences in the structural composition of HAs originating from different soil types were studied after isolation of HAs preparations using FTIR spectroscopy (KBr + HAs pellets, SRATR FTIR method). Results showed that studied HAs preparations could be divided into two groups. First group included HAs isolated from Chernozem and Haplic Luvisol with higher content of aromatic constituents and condensation degree. The second group were HAs isolated from Eutric Cambisol and Fluvi-Eutric Gleysol. They reflected lower content of aromatic compounds, lower condensation degree and more aliphatic structural groups in the HAs molecule. Linear correlation between fractional composition of humus and optical indexes (I501/I487, Q4/6) was found.
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