RESEARCH INTERESTS:

Soil fertility and plant nutrition; root ecophysiology; crop yield potential; nutrient cycling processes; soil organic matter, soil quality and the sustainability of intensive cropping systems; renewable energy agriculture; global food security.

MAJOR PROJECT ACTIVITIES:

The need to meet food demand while protecting environmental quality and natural resources for future generations is a scientific challenge that has been grossly underestimated, and this theme provides a unifying framework for my research. Agricultural systems must ultimately contribute to solving the most pressing environmental problems facing humankind because agriculture is practiced on 33% of the earth’s surface. Hence, the ultimate goal of my research and educational programs is to ensure that increases in food production do not compromise the quality of soil and water resources or threaten the ecological integrity of natural ecosystems. Current projects focus on understanding process controls on carbon sequestration in agricultural soils, energy efficiency of major rainfed and irrigated cropping systems in the north-central USA, the potential for ecological intensification of maize-based cropping systems, and use of crop simulation models to improve crop and soil management decisions. As a member of interdisciplinary research teams, our goal is to seek fundamental knowledge about the dynamic, interactive effects of climate and crop/soil management practices on short- and long-term performance of agroecosystems—with a focus on carbon sequestration, greenhouse gas emissions, nitrogen and energy efficiency, and crop productivity. The ultimate goal is to apply this knowledge towards four objectives:

• To quantify and simulate the potential for net carbon sequestration in agricultural soils at the field, regional, and global levels when all embodied carbon "costs" of production inputs (fossil fuel, fertilizer, irrigation, etc) are accounted for;
• To improve the precision of nutrient management, especially for nitrogen, to optimize profit and fertilizer efficiency while minimizing nutrient losses that have the potential to pollute water resources or contribute to greenhouse gas emissions;
• To improve soil quality to assure long-term sustainability of food production systems.
• To contribute to sustained increases in cereal crop yields on existing cultivated land that is suitable for intensive cultivation to spare natural ecosystems and wildlife from further expansion of agriculture.

EDUCATIONAL INTERESTS:

Having recently stepped down as Head of the Department, my specific role in classroom teaching and extension has yet to be defined. Future contributions will be consistent with my expertise and interests as listed above. Initial contributions have involved training in "Digital Agronomy" ( http://ardc.unl.edu/2005CMWP-Digital.htm ), and organizing the "Nebraska Biofuel Renewable Energy Workshop" on July 20 2005 ( http://webvideo.unl.edu/biofuel.html ).

SELECTED PUBLICATIONS:

• Verma, S.B., Dobermann, A., Cassman, K.G., Walters, D.T., Knops, J.M., Arkebauer, T.J., Suyker, A.E., Burba, G.G., Amos, B., Yang, H.S., Ginting, D., Hubbard, K.G., Gitelson, A.A., Walter-Shea, E.A. 2005. Annual carbon dioxide exchange in irrigated and rainfed maize-based agroecosystems. Agric. Forestry Meteorol. In press.
  
  
• Peng, S, Huang J, Sheehy JE, Laza R, Visperas RM, Zhong X, Centeno GS, Khush G, Cassman KG. 2004. Rice yields decline with higher night temperature from global warming. Proc. Natl. Acad. Sci. (USA) 101: 9971-9975.
  
  
• Yang, H.S., Dobermann, A., Lindquist, J.L., Walters, D.T., Arkebauer, T., and Cassman, K.G. 2004. Hybrid Maize-A maize simulation model that combines two crop modeling approaches. Field Crops Res. 87: 131-154.
  
  
• Nguyen Bao Ve, Olk, D.C., and Cassman, K.G. 2004. Characterization of two humic acid fractions improves estimates of soil N mineralization kinetics in for tropical lowland rice. Soil Sci. Soc. Am. J. In Press.
  
  
• Cassman, K.G., Dobermann, A., Walters, D.T., Yang, H. 2003. Meeting cereal demand while protecting natural resources and improving environmental quality. Annu. Rev. Environ. Resour. 28: 315-358.
  
  
• Tillman, D., Cassman, K.G., Matson, P.A., Naylor, R. and Polasky, S. 2002. Agricultural sustainability and intensive production practices. Nature 418: 671-677.
  
  
• Cassman, K.G., Dobermann, A., and Walters, D. 2002. Agroecosystems, nitrogen-use efficiency, and nitrogen management. AMBIO 31:132-140.
  
  
• Cassman, K.G. 2001. Crop science research to assure food security. In Noesberger, J. et al. (eds) Crop Science: Progress and Prospects. CAB International, Wallingford, UK. pp. 33-51.
  
  
• Cassman, K.G. 1999. Ecological intensification of cereal production systems: Yield potential, soil quality, and precision agriculture. Proc. National Acad. Sci. (USA) 96: 5952-5959.
  
  
• Cassman, K.G. 1999. Ecological intensification of cereal production systems: Yield potential, soil quality, and precision agriculture. Proc. National Acad. Sci. (USA) 96: 5952-5959.
  
  
• Cassman, K.G., S. Peng, D.C. Olks, J.K. Ladha, W. Reichardt, A. Dobermann, and U. Singh. 1998. Opportunities for increased nitrogen-use efficiency from improved resource management in irrigated rice systems. Field Crops Res. 56:7-39.
  
  
• Cassman, K.G., R. Steiner, and A.E. Johnston. 1995. Long-term experiments and productivity indexes to evaluate sustainability of cropping systems. In V. Barnett, R. Payne, and R. Steiner (eds.) Agricultural Sustainability in Economic, Environmental, and Statistical Terms. John Wiley & Sons, Ltd., London, U.K. pp. 231-244.
  
  
• Cassman, K.G. and R. R. Harwood. 1995. The nature of agricultural systems: Food security and environmental balance. Food Policy 20: 439-454.
  
  
• Brouder, S.M. and K.G. Cassman. 1994. Evaluation of a mechanistic model of potassium uptake by cotton in a vermiculitic soil. Soil Sci. Soc. Amer. J. 58:1174-1183.
  
  
• Cassman, K.G., P.W. Singleton, and B.A. Linquist. 1993. Input/output analysis of the cumulative soybean response to phosphorus on an ultisol. Field Crops Res. 34:23-36.
  
  
• Cassman, K.G., B.A. Roberts, and D.C. Bryant. 1992. Cotton response to residual fertilizer potassium as influenced by organic matter and sodium in a vermiculitic soil. Soil Sci. Soc. Am. J. 56:823-830.
  
  
• Cassman, K. G. and D.W. Rains. 1986. A cropping systems approach to salinity management in California. Am. J. Alternative Agric. 1:115-121.
  
  
• Cassman, K. G., D. N. Munns, and D. P. Beck. 1981. Phosphorus nutrition of Rhizobium japonicum: strain differences in phosphate storage and utilization. Soil Sci. Soc. Am. J. 45:517-520.
  
  
• Cassman, K. G., and D. N. Munns. 1980. Nitrogen mineralization as affected by soil moisture, temperature, and depth. Soil Sci. Soc. Am. J. 44:1233-1237.