Rapid Characterization of Northern Cold-Region Soil Organic Matter
Infrared spectroscopy discriminated variations in soil properties and extent of organic matter decomposition for Alaskan soils.
Multivariate analysis of mid-infrared spectra of soils collected from a 2800-km latitudinal transect across Alaska identified spectral bands that can be used to quickly discriminate variations in soil properties, estimate the quantity and chemical composition of soil organic matter (SOM), and assess the degradation state of organic matter stored in northern cold-region soils.
Soil analysis using traditional laboratory methods are often time consuming and expensive, and require relatively large samples—limiting the availability of information on the spatial variability of SOM composition and other soil properties. Mid-infrared spectroscopy of small soil samples proved to be a promising technique for quickly and reliably estimating carbon content and differentiating the degradation state of organic matter stored in northern cold-region soils.
The amount and vulnerability of soil carbon stocks in northern cold-region soils are major sources of uncertainty in the representation of terrestrial biogeochemical cycles in Earth system models. Researchers led by Argonne National Laboratory investigated the suitability of diffuse reflectance Fourier transform mid-infrared (DRIFT) spectroscopy—a nondestructive, cost-effective infrared light analysis method—to discriminate variations in soil physical and chemical properties needed to improve estimates of the spatial variability of carbon stocks and the extent of organic matter decomposition in these soils. Archived soils collected from a 2800-km latitudinal transect across Alaska were analyzed to provide a representative range of climate, vegetation, surficial geology, and soil types for the region. The chemical composition of organic matter, as well as site and soil properties, exerted strong multivariate influences on the DRIFT spectra. Spectral differences indicated that soils with less decomposed organic matter contained greater abundance of relatively fresh materials, such as carbohydrates and aliphatics, whereas clays and silicates were incorporated into more degraded soils. A single spectral band was identified that might be used to quickly estimate soil organic carbon and total nitrogen concentrations. Overall, the study demonstrated that DRIFT spectroscopy can serve as a valuable tool for quickly and reliably assessing variations in the amount and composition of organic matter in northern cold-region soils.
Julie D. Jastrow
Argonne National Laboratory
This study was supported by the Climate and Environmental Science Division’s Terrestrial Ecosystem Science Program of the Office of Biological and Environmental Research, within the U.S. Department of Energy Office of Science under contract DE-AC02-06CH11357 to Argonne National Laboratory.
Matamala, R., F.J. Calderón, J.D. Jastrow, Z. Fan, S.M. Hofmann, G.J. Michaelson, U. Mishra, C.L. Ping. “Influence of site and soil properties on the DRIFT spectra of northern cold-region soils.” Geoderma 305, 80–91 (2017) [DOI:10.1016/j.geoderma.2017.05.014]
Argonne National Laboratory
Lemont, IL 60439