Submitted to: Italian Chapter of International Humic Substances Society
Publication Type: Abstract Only
Publication Acceptance Date: 8/16/1995
Publication Date: N/A
Technical Abstract: The utilization of municipal sewage sludge has become one of our major environmental problems. Regulatory agencies and the general public are determined to find an environmentally acceptable, socially responsible and economically feasible solution. Sludges contain nitrogen, phosphorus, potassium and trace elements that make it a good replacement for traditional fertilizers. The organic matter fraction of sewage sludge can be as high as 50%, benefiting soil physical properties. It is possible that specific compounds in the sludge may be incorporated into the humic substance fraction of the soil. 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 acids. At the end of 20 years, surface soil samples were taken at pre-determined sampling points on 2 sludge-amended terraces and on one control area. These samples were exhaustively extracted with 0.1M Na4P2O7/NaOH under N2 and humic acids were isolated using a modified IHSS standard procedure. Characterizations included: yield of humic acid (HA), elemental composition, cation exchange capacity, sugars and amino acids, Fourier transform infrared (FTIR), 13C-nuclear magnetic resonance (NMR), and fluorescence spectra. Sludge-amended soil HAs showed variations from the non-amended soil HAs in elemental , sugar, and amino acid contents. FTIR and NMR spectra reflected these differences. Sludge and soil HAs were markedly different in composition and spectra. The impact of sewage sludge application on soil HAs will be discussed.