Submitted to: International Humic Substances Society Conference
Publication Type: Proceedings
Publication Acceptance Date: 5/1/2008
Publication Date: 9/14/2008
Citation: He, Z., Ohno, T., Olk, D.C., Wu, F., Honeycutt, C.W., Mao, J. 2008. Capillary Electrophoresis and Fluorescence Excitation-Emission Matrix Characterization of Soil Mobile and Calcium Humates. International Humic Substances Society Conference. From molecular understanding to innovative applications of humic substances, Vol. I. Humus Sapiens, Moscow, Russia.
Technical Abstract: Capillary electrophoresis (CE) and Excitation-emission matrix (EEM) fluorescence spectroscopy have been used in natural organic matter (NOM) studies. The mutual relevance of data collected from each of the two methods provides novel insight into the correlation of complex NOM fluorescence spectra to specific NOM fractions. We applied this approach to explore the characteristics of soil mobile humic acid (MHA) and recalcitrant calcium humate (CaHA) in relation to different cropping management practices. Soil samples were collected from a private farm in Hamilton County near Phillips, Nebraska, USA on an irrigated field with a continuous corn system. Nutrient management treatments included application of beef cattle feedlot manure, inorganic N fertilizer, and an unfertilized control. The MHA and CaHA fractions were extracted based on an established procedure. Our results demonstrated that the MHA and CaHA fractions extracted from these soils possessed characteristic capillary electrophoretic and EEM fluorescence profiles. UV irradiation caused these profiles to change. However, no remarkable difference in profiles among soils with different nutrient treatments suggested that crop management practices under the experimental period (6 years) did not significantly alter the chemical nature of humic fractions in these soils.