ARS | Publication request: FATTY ACID PROFILES OF HIGHLY-ERODIBLE LANDS IN THE SOUTHERN HIGH PLAINS

Submitted to: Trans American Geophysical Union
Publication Type: Proceedings
Publication Acceptance Date: October 1, 1997
Publication Date: N/A

Technical Abstract: Fatty acids, organic residues which become bound to the mineral portion of soils and sediment, have been widely used as a biomarker of source environ- ments in oceanography and limnology. We are investigating their feasibility as a tracer of aeolian sediment transport; the technique should be equally applicable to fluvial transport processes. Gas chromatography of fatty acid dmethyl esters was used to determine the presence and relative amount of 12 different fatty acids in 157 samples of highly-erodible land surfaces in the Southern High Plains. Principal component analysis and other statisti- cal techniques determined fatty acid assemblages which were significantly (p>.7) associated with specific soil or sediment types, agricultural systems, and other land uses. Discrete variations in the presence, absence, and/or relative amounts of fatty acids were associated with croplands and rangelands as general categories, as well as a few crops (wheat, cotton) and agricultural practices (chemical termination of wheat in rotation with cotton). Other fatty acid groups were associated with specific land uses (unpaved roads, landfill), soil/sediment textures (aeolian sand), road materials (earth-surface, calcium carbonate gravel), and specific geograph- ical areas (Terry County, Texas). Fatty acid profiles could not be reliably used to separate lands under most specific agricultural practices (irrigated vs. dryland fields, conventional tillage/reduced till/no-till), either at small (individual farm) or large (8000 sq. km) scales. These results show that fatty acids do have potential as a biomarker of soil erosion and terrestrial sediment transport from different land management systems.