The origin and identity of low molecular weight organic acids in soils will be studied in coniferous ecosystems in the Pacific Northwest. These acids along with fulvic acids may drive the soil formation process, podsolization, in these ecosystems. Some of these acids may control the availability of Ca and Al to plants from soil solution. The work could go a long way toward explaining the tolerance of conifers to high Al soils and to the maintenance of available Ca in the rhizosphere under these conditions. The work is also significant to understanding what controls the concentrations of dissolved organic carbon and Al that move from the soil to streams in the forested landscape. Three potential sources of organic acids will be examined; root exudates, decaying organic matter, and mycorrhizal fungi. Both field and laboratory studies of organic acid sources will be undertaken. Field research will include comparison of organic acids in soils of root-free and control plots. Soil solutions will be sampled by lysimetry and extractions. A variety of state-of-the-art techniques will be used to identify low molecular weight acids. These techniques include gas chromatography, high pressure liquid chromatography and GC/MS. The forms in which Al exist in the soil-root matrix will be determined using a special application of electron microscopy. Dr. Ugolini has an outstanding research record in this area. The institutional support available to him at the University of Washington is first-rate.
