Submitted to: International Humic Substances Society Conference
Publication Type: Abstract Only
Publication Acceptance Date: 11/2/1996
Publication Date: N/A
Technical Abstract: Soils from a 16-ha terraced watershed at the Rosemount Agricultural Experiment Station of the University of Minnesota were studied to determine the effect of long-term application of sewage sludge on soil humic substances. At the end of 20 years, surface soil samples were taken on two sludge-amended areas and on the control area. These samples were exhaustively extracted and humic and fulvic acids were isolated. Selected freeze-dried sludges, representing anaerobic and aerobic treatment plants, and a recent application sludge were extracted and isolated for humic and fulvic acids in the same manner. Characterizations included: yield of humic and fulvic acids, elemental composition, cation exchange capacity, sugars and amino acids, and Fourier transform infrared (FTIR), **13C-nuclear magnetic resonance (NMR) and fluoresence spectroscopy. The two sludge-amended soil humic acids and the one non-amended soil humic were alike in chemical composition and exhibited aromatic structures. The four sludge humic acids were similar to each other, but markedly different from the soil humic acids in composition and were highly aliphatic in structure. The addition of sludge humic acids appear to have little impact on the chemical composition of soil humic acids. The fulvic acids of sludges and soils were correspondingly different from each other.