Professor of Soil Science

Iowa State University
Agronomy Department
Ames, Iowa 50011

Telephone: 515-294-2415
E-mail: thompsonm@iastate.edu

The research program centers on environmental soil chemistry and mineralogy. The program's primary thrust is the investigation of organomineral complexes, phosphorus, and anthropogenic organic compounds in soils. The overall aim of these studies is to identify chemical and physical conditions that favor movement and transformations of
organic matter, contaminants, and clay in soils.


1. Recalcitrant Soil Organic Matter in Agricultural Landscapes
Principal Investigators: M.L. Thompson, Agronomy, and K. Schmidt-Rohr, Chemistry, ISU.

This research is 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. To identify and quantify recalcitrant components of soil organic matter, we apply advanced nuclear magnetic resonance spectroscopy as well as diffuse reflectance Fourier-transform infrared spectroscopy, extractions with organic solvents, and thermal oxidation techniques. Both scanning and transmission electron microscopy are critical to understanding the effects of chemical extractions on RSOM as well as documenting its association with inorganic soil components at the micrometer and nanometer scales. Energy dispersive x-ray analysis will allow us to differentiate organic compounds from inorganic minerals in plant tissue and in the soil, either before or after labeling the RSOM with heavy metals. 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.

2. Colloid-Mediated Transport of Hormones with Land-Applied Manure
Co-Project Directors:  Robert Horton and  Michael L. Thompson, Agronomy Department, ISU

Endocrine-disrupting hormones may enter the environment via land application of livestock manure. With respect to both livestock production and soils, Iowa is the prototype for agriculture in the Midwest. Our hypothesis is that the risk of hormone transport can be better understood by knowledge of the mechanisms of sorption, desorption, and transport of colloid-hormone complexes. Objectives are to (1) determine the rate, intensity, and capacity for adsorption and desorption of estrogens by colloidal components of cattle manure and three Iowa soils, (2) quantify the impact of physical and chemical variables that regulate colloid-mediated transport of estrogens in soils, and (3) quantify colloid-mediated pathways in the profile-scale dissipation of manure-associated estrogens. The research plan focuses on: (1) adsorption-desorption processes that determine how much of a land-applied hormone is transferred from manure to the aqueous phase or to the soil, (2) leaching of colloid-associated estrogens through aggregated, structured soils, and (3) transport of colloid-associated estrogens with runoff. This scale-integrated research will strengthen the development of transport models that are indispensable for assessing the environmental risk of hormones in land-applied livestock waste. The work proposed and will address issues where current knowledge is critically incomplete. At the project’s conclusion, we will have identified key mechanisms by which estrogens interact with colloidal organics in cattle manure and in soil. We will also have identified how those mechanisms can be incorporated into predictive models of hormone transport in or over soils.

3. Comparison of Biofuel Systems: COBS
Project Investigators: Matt Liebman, Robert Horton, Rick Cruse, Michael Thompson, Matt Helmers, Kirsten Hofmockel, Fernando Miguez, and Robert Anex

This project seeks to identify and develop cropping systems that produce large quantities of biofuel feedstocks while protecting soil and water resources and increasing biodiversity on the Iowa landscape. Treatments in the COBS experiment include a conventional corn-soybean cash grain system; continuous corn grown for grain and stover, with and without a winter cover crop; a mixture of perennial prairie plants fertilized for high biomass production; and a highly diverse, unfertilized mixture of prairie plants, which serves as a benchmark for understanding the functional characteristics of a native plant community.

Our central premise is that cropping systems designed to produce large amounts of biomass, with high net energy return, can simultaneously create significant environmental benefits. Our working hypotheses are that (1) cover crops can reduce nutrient losses from corn production systems, (2) diverse mixtures of perennial plants can produce nearly as much biomass as conventionally managed corn, but with greater economic and energetic efficiency; and (3) diverse plant mixtures used for feedstock production can emit fewer pollutants to drainage water, sequester more carbon, and reduce greenhouse gas emissions relative to corn- and soybean-based cropping systems.

We are comparing systems by measuring plant productivity, resource use efficiency, nutrient dynamics, soil organic matter maintenance and production, carbon sequestration, CO2 emissions, and drainage water quantity and quality. Direct comparisons within a spectrum of cropping systems lead to informed analyses of the advantages and disadvantages of each system.

Agronomy 459 / 559, Soil Chemistry (with laboratory)
Agronomy 259X, Organic Compounds in Plant and Soil Environments

Agronomy 388X, Agronomic Sciences in Theory and Practice

Ohio State University, Columbus, OH, Ph.D., Agronomy (Soil Genesis), 1980
University of Illinois, Urbana-Champaign, B.S., with High Honors, Agricultural Sciences, 1974

Agronomy Department, Iowa State University, Ames
Professor (2005-present), Pioneer Hi-Bred Professor of Agronomy (2007 – 2010)
Associate Professor (1989-2005), Assistant Professor (1980-1989)

Associate Editor, Journal of Environmental Quality (2002 – 2008)
Chair-elect, Chair and Past-Chair of Division S-9 (Soil Mineralogy), Soil Science Society of America, 2005 – 2007

Fellow, American Association for the Advancement of Science, 2010
Fellow, Soil Science Society of America, 2008
Fellow, American Society of Agronomy, 2008
Outstanding Associate Editor, Journal of Environmental Quality, 2008


Recent Research Publications
(*graduate students and post-doctoral research associates)

Hongthanat*, N., J.L. Kovar, M.L. Thompson. 2011. Sorption indices to estimate risk of soil phosphorus loss in the Rathbun Lake Watershed, Iowa. Soil Sci. 176:237-244.

Fang, X., T. Chua, K. Schmidt-Rohr, and M.L. Thompson. 2010. Quantitative 13C NMR of whole and fractionated Iowa Mollisols for assessment of organic matter composition. Geochim. Cosmochim. Acta. 74:584-598.

Laird, D.A., M.A. Chappell*, D.A. Martens, R.L. Wershaw, and M. 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. In press.

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. In press.

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.

Mbila*, M.O. and M.L. Thompson. 2004. Plant-available Zn and Pb in soils at the Mines of Spain, Iowa. J. Environ. Qual. 33:553-558

Han*, N., and M.L. Thompson. 2003. The influence of biosolids-derived dissolved organic matter on Cu transport in an aquifer material. J. Environ. Qual. 32:1829-1836.

Mbila*, M.O., M.L. Thompson, J. Mbagwu, and D.A. Laird. 2003. Morphological and chemical properties of selected sludge-amended Nigerian soils. Soil Sci. 168:660-669.

Mao, J.-D., L.S. Hundal*, K. Schmidt-Rohr, and M.L. Thompson. 2003. Nuclear magnetic resonance and diffuse-reflectance infrared Fourier-transform spectroscopy of sludge-derived biocolloidal organic matter. Environ. Sci. Technol. 37:1751-1757

Lee, J., L.S. Hundal*, R. Horton, and M.L. Thompson. 2002. Influence of ionic strength and flow velocity on sorption and transport behavior of naphthalene in aggregated soil. J. Environ. Qual. 31:1716-1721.

Mao, J.-D., L.S. Hundal*, M.L. Thompson, and K. Schmidt-Rohr. 2002. Correlation of poly(methylene)-rich aliphatic domains in humic substances with sorption of a nonpolar organic contaminant, phenanthrene. Environ. Sci. Technol. 36:929-936.

Hundal*, L.S., M.L. Thompson, D.A. Laird, A.M. Carmo*. 2001. Sorption of phenanthrene by reference smectites. Environ. Sci. Technol. 35:3456-3461.

Mbila*, M.O., M.L. Thompson, J.S.C. Mbagwu, and D.A. Laird. 2001. Distribution and movement of sludge-derived trace metals in a Nigerian Ultisol. J. Environ. Qual. 30:1667-1674.

Sui*, Y., and M.L. Thompson. 2000. Phosphorus sorption, desorption, and buffering capacity in a biosolids-amended Mollisol. Soil Sci. Soc. Am. J. 64:164-169.

Carmo*, Ana M., L.S. Hundal*, and M.L. Thompson. 2000. Sorption of hydrophobic organic compounds by soil materials: Application of unit equivalent Freundlich sorption coefficients. Environ. Sci. Technol. 34:4363-4369.

Hundal*, L.S., A.M. Carmo*, W.L. Bleam, M.L. Thompson. 2000. Sulfur in biosolids-derived fulvic acid: characterization by XANES and selective dissolution approaches. Environ. Sci. Technol. 34:5184-5188.

Wu, J., D.A. Laird, and M.L. Thompson. 1999. Sorption and desorption of copper on soil clay components. J. Environ. Qual. 28:334-338.

Han*, N., and M.L. Thompson. 1999a. Soluble organic carbon in a biosolids-amended Mollisol. J. Environ. Qual. 28:652-658.

Han*, N., and M.L. Thompson. 1999b. Copper-binding ability of dissolved organic matter derived from anaerobically digested biosolids. J. Environ. Qual. 28:939-944.

Sui*, Y., M.L. Thompson, and C.W. Mize. 1999a. Redistribution of biosolids-derived total P applied to a Mollisol. J. Environ. Qual. 28:1068-1074.

Sui*, Y., M.L. Thompson, and C. Shang*. 1999b. Fractionation of phosphorus in a Mollisol amended with biosolids. Soil Sci. Soc. Am. J. 63:1174-1180.

Recent Chapters in Books
Sandor, J., L. Burras, and M. Thompson. 2004. Human impacts on soil formation. Encyclopedia of Soils in the Environment, edited by D. Hillel. p. 520- 532. Elsevier. Invited.

Thompson, M.L., and L. Ukrainczyk. 2002. Micas. p. 431-466. In J.B. Dixon and Darrell Schulze (ed.) Soil Mineralogy with Environmental Applications. Soil Sci. Soc. Am. Book Ser. 7. Madison, WI. Invited.

Olson, C.G., M.L. Thompson, and M.J. Wilson. 1999. p. F77-F123. Phyllosilicates. In Malcolm Sumner (ed.) The Handbook of Soil Science. CRC Press, Boca Raton , FL. Invited.

Recent Technical Reports

Thompson, M.L., J. Seibel, T. Chua. 2007. Nutrient Loading in Streams Near Two Wastewater Treatment Plants in Central Iowa. Final Project Report to Environmental Protection Agency, Office of Water, Office of Science and Technology, Health and Ecological Criteria Division, Ecological and Health Processes Branch, Nutrient Criteria Program.

Thompson, M.L., and K.J. Poppens. 2004. Using the Iowa Phosphorus Index to assess risk of off-site P movement in biosolids management. A demonstration project for the Iowa Water Pollution Control Association. Compact disk published by the Agronomy Department, Iowa State University.

Thompson, M., R. Blaisdell, R. Conant, W. Dick, A. Dobermann, C. Izaurralde, M. Ransom, C. Rice, P. Robertson, J. Stuth. 2003. Recommended procedures for collecting, processing, and analyzing soil samples in CASMGS research projects. CASMGS web site: http://www.casmgs.colostate.edu.

Colletti, J., M.L. Thompson, R.C. Schultz, C.W. Mize, and I.C. Anderson. 1998. Demonstration of an agroforestry system to minimize pollution hazards from land application of treated municipal sludge. Final report for Project 95-47, Leopold Center for Sustainable Agriculture, Iowa State University.

Thompson, M.L. 1997. Colloid-facilitated transport of heavy metals in a sludge-amended agroforestry system. Technical Report for U. S. Environmental Protection Agency Grant No. R81-9996-01-0.

Thompson, M.L., J. Colletti, R.C. Schultz, C.W. Mize, and I.C. Anderson. 1996. Demonstration of an agroforestry system to minimize pollution hazards from land application of treated municipal biosolids. Report to the City of Ames by the Agronomy and Forestry Departments, Iowa State University.

Thompson, M.L., R.L. Scharf*, and C. Shang*. 1995. Zero-tension lysimeters: An improved design to monitor colloid-facilitated contaminant transport in the vadose zone. Characterization, Monitoring, & Sensor Technology Crosscutting Program, Office of Technology Development, U.S. Department of Energy. Ames Laboratory Publication IS-5117, UC-600.