Title: Characterization of organic matter in beef feedyard manure by ultraviolet-visible and Fourier transform infrared spectroscopies Authors
Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: September 15, 2013
Publication Date: November 4, 2013
Citation: Waldrip, H., He, Z., Todd, R.W., Hunt, J.F., Rhoades, M.B., Cole, N.A. 2014. Characterization of organic matter in beef feedyard manure by ultraviolet-visible and Fourier transform infrared spectroscopies. ASA-CSSA-SSSA Annual Meeting Abstracts. poster number 1105. Technical Abstract: Manure from beef cattle feedyards is a valuable source of nutrients for crops and assists with maintaining soil fertility and quality. However, the humification and decomposition processes that occur during feedyard manure’s on-farm life cycle will influence the forms, concentrations, and availability of carbon (C) and nutrients such as nitrogen (N) and phosphorus (P) for utilization by crops and soil microorganisms, thereby affecting its fertilizer value. An improved understanding of the chemistry of feedyard manure organic matter (OM) will provide better estimates of the potential fertilizer value of manure taken from different sources on a feedyard and help identify factors that could lead to nutrient loss via NH3 and N2O volatilization and NO3- leaching. In this study, we utilized Fourier-transform infrared (FT-IR) and UV-visible (UV-vis) spectroscopies to characterize the structural and functional properties of OM in feedyard manure and water extractable OM (WEOM) taken from different locations (surface manure, manure pack, settling basin, retention pond) from a typical commercial beef feedyard in the Texas Panhandle. In addition, we also used FT-IR and UV-vis spectrocopies to evaluate the changes in OM and WEOM of pen manure following surface application to rangeland. The primary findings were that, as beef manure completes its on-farm life cycle, concentrations of dissolved organic C and N can be decreased by 98 and 95%, respectively. UV-vis spectral analysis of WEOM indicated large differences between the manures from different sources in molecular weight, lignin content, and proportion of humified OM. FT-IR spectra of whole manures and WEOM were typical of humic acids, and comparison of manures from the different sources showed preferential decomposition of fats, lipids, and proteins over aromatic polysaccharides such as lignin. Further work is still required to evaluate how the application of different feedyard manures will influence soil metabolic functioning and fertility.