ARS | Publication request: Differentiating sources of soil water soluble organic matter by UV-visible spectral models

Submitted to: Soil Organic Matter
Publication Type: Abstract Only
Publication Acceptance Date: March 30, 2011
Publication Date: July 11, 2011
Citation: Zhang, M., He, Z. 2011. Differentiating sources of soil water soluble organic matter by UV-visible spectral models [abstract]. 3rd International Symposium on Soil Organic Matter Dynamics. July 11-14, 2011, Leuven, Belgium. p. 419.

Technical Abstract: UV-visible spectral models have been used to differentiate sources of dissolved organic matter in sea/fresh waters. Little information is available on using these models to characterize soil soluble organic matter. The objective of this study was to determine sources of soil soluble organic matter by use of spectral models. Soil samples (different times and soil depths) were taken from agricultural fields under different cropping management practices in the USA. Soluble organic matter was extracted by deionized water with a soil:solution ratio of 1:10 followed by filtering with <0.45 um membranes. The carbon and nitrogen concentrations and UV-Vis absorbance in the water extracts were determined. Spectral slopes were obtained by use of a nonlinear approach to simulate solution absorptivity from different treatments.Results indicated that spectral slopes increased over time for all treatments. Little difference in spectral slopes was found between poultry and chemical fertilizer treatments. For different soil sampling depths, spectral slopes decreased as the sampling depth increased. In summary, spectral modeling showed promises for characterization of soil soluble organic matter. Future work should emphasize model comparisons and optimal wavelength for simulation.