Climate Science Program

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Michael Thompson

Professor of Soil Science
Pioneer Hi-Bred Professor of Agronomy



Office: 2503 Agronomy Hall

Phone: 515-294-2415





Department: Agronomy

Research Interests: Soil Mineralogy and Chemistry

Brief description of current research:

My primary research responsibility is in environmental soil mineralogy.

I am currently conducting a scale-integrated program to improve understanding of recalcitrant (decomposition-resistant) soil organic matter (RSOM) in cultivated Mollisols, the most widely distributed soils in the Upper Midwest. RSOM includes charcoal, lipids, lignin, and humic substances and is a critical component of biogeochemical models of carbon cycling. Yet little is known about its spatial distribution at the landscape or micrometer scales. The project examines both the spatial and temporal variability of belowground processes related to carbon. In two classic suites of Mollisols that are developed in till and loess, we are quantifying RSOM with respect to landscape position and depth. We are also measuring the seasonal and annual rates at which recalcitrant components in crop biomass are added to the soil. With a focus on quantifying the spatial distribution of RSOM components, this project is unique in its explicit attempt to connect measurements of molecular-scale soil properties with their distribution in soil at landscape scales.

My primary teaching responsibility is for Agronomy 459, Soil Chemistry (offered each year), and Agronomy 555 and 555L, Soil Clay Mineralogy and Soil Clay Mineralogy Laboratory (offered in alternate years).

Recent publications:
Laird, D.A., M.A. Chappell, D.A. Martens, R.L. Wershaw, and M.L. Thompson. 2008. Distinguishing black carbon from biogenic humic substances in soil clay fractions. Geoderma. 143:115-122.

Pereira, T.R., D.A. Laird, M.L. Thompson, C.T. Johnston, B.J. Teppen, H. Li, and S.A. Boyd. 2008. Role of smectite quasicrystal dynamics in adsorption of dinitrophenol. Soil Sci. Soc. Am. J. 72:347-354.

Mao, J.D., X. Fang, K. Schmidt-Rohr, A.M. Carmo, L.S. Hundal, and M.L. Thompson. 2007. Molecular-scale heterogeneity of humic acid in particle-size fractions of two Iowa soils. Geoderma 140:17-29.

Khanal, S.K., B. Xie, M.L. Thompson, S. Sung, S.-K. Ong, and J. van Leeuwen. 2006. Fate, transport, and biodegradation of natural estrogens in the environment and engineered systems. Environ. Sci. Technol. 40:6527-6546.

Hundal, L., and M.L. Thompson. 2006. Soil aggregation as a source of variation in sorption isotherms of hydrophobic organic compounds. Soil Sci. 171:355-363.

Chappell, M.A., D.A. Laird, M.L. Thompson, and V.P. Evangelou. 2006. Co-sorption of atrazine and a lauryl polyoxyethylene oxide nonionic surfactant on smectite. J. Agric. Food Chem. 53:10127-10133.

Chappell, M.A., D.A. Laird, M.L. Thompson, H. Li, B.J. Teppen, V. Aggarwal, C.T. Johnston, and S.A. Boyd. 2005. Influence of smectite hydration and swelling on atrazine sorption behavior. Environ. Sci. Technol. 39:3150-3156.

Sonon, L.S., and M.L. Thompson. 2005. Sorption of a nonionic polyoxyethylene lauryl ether surfactant by 2:1 layer silicates. Clays Clay Miner. 53:45-54.