Degrees:

• B.A., Chadron State College, 1971
• Ph.D. University of Nebraska, 1977

Research Interests:

Soil and crop management, cropping systems, soil fertility, carbon sequestration.

Major Project Activities:
My current projects include investigations into the effects of cropping system and N fertilizer combinations on fertilizer use efficiency, crop yields, precipitation use efficiency, residual N levels, and carbon storage (sequestration) in dryland and irrigated production systems. Research activities also include analyses of long-term data sets to develop decision tools for use in precision agriculture and investigations into the effects of residue removal on crop production and soil organic matter levels.

Publications:

Varvel, G.E., and Wilhelm, W.W. Soil Carbon Levels in Irrigated Western Corn Belt Rotations. Agronomy Journal 100:1180-1184. 2008.

Varvel, G.E., Vogel, K.P., Mitchell, R.B., Follett, R.F., and Kimble, J.M. 2008. Comparison of Corn and Switchgrass on Marginal Soils for Bioenergy. Biomass & Bioenergy. 32:18-21. http://hdl.handle.net/10113/17521

Varvel, G.E., Wilhelm, W.W., Shanahan, J.F., and Schepers, J.S. 2007. An Algorithm for Corn Nitrogen Recommendations Using a Chlorophyll Meter Based Sufficiency Index. Agronomy Journal 99:701-706. http://hdl.handle.net/10113/11211

Varvel, G.E. 2006. Soil Organic Carbon Changes in Diversified Rotations of the Western Corn Belt. Soil Science Society of America Journal 70:426-433. http://hdl.handle.net/10113/4144

Wienhold, B.J., Pikul, J.L., Jr., Liebig, M.A., Vigil, M.F., Varvel, G.E., and Doran, J.W. 2006. Cropping System Effects on Soil Quality in the Great Plains: Summary from a Regional Project. Renewable Agriculture and Food Systems. 21(1):49-59. http://hdl.handle.net/10113/8722

Varvel, G.E., Riedell, W.E., Deibert, E., McConkey, B., Tanaka, D.L., Vigil, M.F., and Schwartz, RC. 2006. Great Plains Cropping System Studies for Soil Quality Assessment. Renewable Agriculture and Food Systems. 21(1):3-14. http://hdl.handle.net/10113/284

Wilhelm, W.W., Varvel, G.E., and Schepers, J.S. 2005. Corn Stalk Nitrate Concentration Profile. Agronomy Journal 97:1502-1507. http://hdl.handle.net/10113/3719 (IANR Jr Series No.  14914).

Mitchell, R.B., Vogel, K.P., Varvel, G.E., Klopfenstein, T.J., Clark, R.T., and Anderson, B.E. 2005. Big Bluestem Pasture in the Great Plains: An Alternative for Dryland Corn. Rangelands. 27(2):31-35. (IANR Jr Series No.  14509)(ARS Log # 161917).

Liebig, M.A., Miller, M.E., Varvel, G.E., Doran, J.W., and Hanson, J.D. 2004. AEPAT: Software for Assessing Agronomic and Environmental Performance of Management Practices in Long-Term Agroecosystem Experiments. Agronomy Journal 96:109-115. http://hdl.handle.net/10113/8381

Varvel, G.E., and Wilhelm, W.W. 2003. Soybean nitrogen contribution to corn and sorghum in two-year cropping systems in the Western Corn Belt. Agronomy Journal 95:1220-1225. http://hdl.handle.net/10113/8527

Eghball, B., Shanahan, J.F., Varvel, G.E., and Gilley, J.E. 2003. Reduction of high soil test phosphorus by crop removal. Agronomy Journal 95:1233-1239. http://hdl.handle.net/10113/8528

Liebig, M.A., and Varvel, G.E. 2003. Effects of Western Corn Belt cropping systems on agroecosystem functions. Agronomy Journal 95:316-322.

Varvel, G.E., Liebig, M.A., and Doran, J.W. 2002. Soil organic matter assessments in a long-term cropping system study. Communications in Soil Science and Plant Analyses 33(13&14), 2119-2130.

Liebig, M.A., Varvel, G.E., Doran, J.W. and Wienhold, B.J. 2002. Crop sequence and N fertilization effects on soil properties in the Western Corn Belt. Soil Science Society of America Journal 66: 596-601. http://hdl.handle.net/10113/7978

Helmers, G.A., Yamoah, C.F., and Varvel, G.E. 2001. Separating the impacts of crop diversification and rotations on risk. Agronomy Journal 93:1337-1340. http://hdl.handle.net/10113/16642

Shanahan, J.F, Schepers, J.S., Francis, D.D., Varvel, G.E., Wilhelm, W.W., Tringe, J.M., Schlemmer, M.R, and Major, D.J. 2001. Use of remote sensing imagery to estimate corn grain yield. Agronomy Journal 93:583-589. http://hdl.handle.net/10113/17169

Liebig, M.A., Varvel, G.E., and Doran, J.W. 2001. A simple performance-based index for assessing multiple agroecosystem functions. Agronomy Journal 93:313-318. http://hdl.handle.net/10113/14472

Varvel, G.E. 2000. Crop rotation and nitrogen effects on normalized grain yields in a long-term study. Agronomy Journal 92:938-941. http://hdl.handle.net/10113/17412

Varvel, G.E., Schlemmer, M.R., and Schepers, J.S. 1999. Relationship between spectral data from an aerial image and soil organic matter and phosphorus levels. Precision Agriculture J. 1:291-300. http://hdl.handle.net/10113/17520

Wilhelm, W.W., Liebig, M.A., Varvel, G.E., and Blackmer, T.M. 1999. Effect of crop rotation, hybrid, and N-fertilizer rate on mid-season stalk breakage in corn. Agronomy Journal 91:160-165. http://hdl.handle.net/10113/17846

Yamoah, C.F., Varvel, G.E., Waltman, W.J., and Francis, C.A. 1998. Long-term nitrogen use and nitrogen-removal index in continuous crops and rotations. Field Crops Research. 57:15-27. http://hdl.handle.net/10113/17844 (IANR Jr Series No.  11,853).  115 submitted 3 97

Yamoah, C.F., Francis, C.A., Varvel, G.E., and Waltman, W.J. 1998. Weather and management impact on crop yield variability in rotations. Journal of Production Agriculture 11:219-225. http://hdl.handle.net/10113/17845 (IANR Jr Series No. 11,822).  115 submitted 2 97

Varvel, G.E., Schepers, J.S., and Francis, D.D. 1997. Ability for in-season correction of nitrogen deficiency in corn using chlorophyll meters. Soil Science Society of America Journal 61:1233-1239. http://hdl.handle.net/10113/17640 (IANR Jr Series No. 11,687).  115 submitted7  96

Varvel, G.E., Schepers, J.S., and Francis, D.D. 1997. Chlorophyll meter and stalk nitrate techniques as complementary indices for residual nitrogen. Journal of Production Agriculture 10:147-151.

http://hdl.handle.net/10113/17408 (IANR Jr Series No. 11,283).

Eghball, B. and Varvel, G.E. 1997. Fractal analysis of temporal yield variability of crop sequences: implications for site-specific management. Agronomy Journal 89:851-855. http://hdl.handle.net/10113/17162 (IANR Jr Series No.  11,747).  115 submitted 9 96

Blackmer, T.M., Schepers, J.S., Varvel, G.E., and Meyer, G.E. 1996. Analyses of aerial photography for nitrogen stress within corn fields. Agronomy Journal 88:729-733. http://hdl.handle.net/10113/16822IANR Jr Series No 11,038).

Blackmer, T.M., Schepers, J.S., Varvel, G.E., and Walter-Shea, E.A. 1996. Nitrogen deficiency detection using reflected shortwave radiation from irrigated corn canopies. Agronomy Journal 88:1-5. http://hdl.handle.net/10113/16821IANR Jr Series No 10,887).

Varvel, G.E. 1995. Precipitation use efficiency of soybean and grain sorghum in monoculture and rotation systems. Soil Science Society of America Journal 59:527-531. http://hdl.handle.net/10113/17399

Schepers, J.S., Varvel, G.E., and Watts, D.G. 1995. Nitrogen and water management strategies to reduce nitrate leaching under irrigated maize. Journal of Contaminant Hydrology. 20:227-239. http://hdl.handle.net/10113/17160

Ellis, J.R., Watson, D.M.H., Varvel, G.E., and Jawson, M.D. 1995. Methyl bromide soil fumigation alters plant element concentrations. Soil Science Society of America Journal 59:848-852.IANR Jr Series No 10,973).  115 submitted 3 91

Varvel, G.E. 1994. Rotation and nitrogen fertilization effects on changes in soil carbon and nitrogen. Agronomy Journal 86:319-325. http://hdl.handle.net/10113/17398115 to NPA July, 1993 (Journal Series #10495).

Varvel, G.E. 1994. Monoculture and rotation effects on precipitation use efficiency of corn. Agronomy Journal 86:204-208. http://hdl.handle.net/10113/17397 115 to NPA 2 93. (Journal Series #10273).

Karlen, D.L., Varvel, G.E., Bullock, D.G., and Cruse, R.M. 1994. Crop Rotations for the 21st Century. Adv. Agron. 53:1-45.(Book chapter). 115 prepared by Karlen Nov 93

Blackmer, T.M., Schepers, J.S., and Varvel, G.E. 1994. Light reflectance compared with other nitrogen stress measurements in corn leaves. Agronomy Journal 86:934-938. http://hdl.handle.net/10113/16820IANR Jr Series No 10593).

Brown, R.E., Varvel, G.E., and Shapiro, C.A. 1993. Residual effects of interseeded hairy vetch on soil nitrate-nitrogen levels. Soil Science Society of America Journal 57:121-124.  http://hdl.handle.net/10113/16816115 submitted 6 92 (IANR Jr Series #10055).

Varvel, G.E., and Peterson, T.A. 1992. Nitrogen fertilizer recovery by soybean in monoculture and rotation systems. Agronomy Journal 84:215-218. 1992. http://hdl.handle.net/10113/17395115 submitted 4 91 (Jr Series #9554 ).

Varvel, G.E., and Peterson, T.A. 1991. Nitrogen fertilizer recovery by grain sorghum in monoculture and rotation systems. Agronomy Journal 83:617-622. http://hdl.handle.net/10113/17394115 submitted 4 91

Varvel, G.E., and Peterson, T.A. 1990. Residual soil N as affected by continuous, two-year, and four-year crop rotation systems. Agronomy Journal 82:958-962. http://hdl.handle.net/10113/17393

Varvel, G.E., and Peterson, T.A. 1990. Nitrogen fertilizer recovery by corn in monoculture and rotation systems. Agronomy Journal 82:935-938. http://hdl.handle.net/10113/17392

Varvel, G.E., Havlin, J.L., and Peterson, T.A. 1989. Nitrogen placement evaluation for winter wheat in three fallow tillage systems. Soil Science Society of America Journal 53:288-292. http://hdl.handle.net/10113/17391

Peterson, T.A., and Varvel, G.E. 1989. Crop yield as affected by rotation and N rate. III. Corn. Agronomy Journal 81:735-738. http://hdl.handle.net/10113/16918

Peterson, T.A., and Varvel, G.E. 1989. Crop yield as affected by rotation and N rate. II. Grain sorghum. Agronomy Journal 81:731-734. http://hdl.handle.net/10113/16917

Peterson, T.A., and Varvel, G.E. 1989. Crop yield as affected by rotation and N rate. I. Soybean. Agronomy Journal 81:727-731.  http://hdl.handle.net/10113/16916

Gilley, J.E., Finkner, S.C., and Varvel, G.E. 1987. Size distribution of sediment as affected by sorghum and soybean residue. Transactions of the American Society of Agricultural Engineers 30:1419-1424. http://hdl.handle.net/10113/17201

Gilley, J.E., Finkner, S.C., and Varvel, G.E. 1987. Slope length and surface residue influences on runoff and erosion. Transactions of the American Society of Agricultural Engineers 30:148-152. http://hdl.handle.net/10113/17204

Varvel, G.E., and Severson, R.K. 1987. Evaluation of cultivar and nitrogen management options for malting barley. Agronomy Journal 79:459-463.

Gilley, J.E., Finkner, S.C., and Varvel, G.E. 1986. Runoff and erosion as affected by sorghum and soybean residue. Transactions of the American Society of Agricultural Engineers 29:1605-1610. http://hdl.handle.net/10113/17203

Varvel, G.E., Meredith, H.L., and Severson, R.K. 1986. Field evaluation of acid-base fertilizers on spring wheat. Agronomy Journal 78:775-779.

Varvel, G.E. 1984. A copper-phosphorus interaction in wheat. Journal of Plant Nutrition 7:1623-1634.

Varvel, G.E., and Severson, R.K. 1984. Pneumatic applicator for uniform distribution of dry fertilizer on small plots. Agronomy Journal 76:1021-1022.

Varvel, G.E. 1983. Effect of banded and broadcast placement of copper fertilizers on correction of copper deficiency. Agronomy Journal 75:99-101.

Varvel, G.E. 1982. The effects of anhydrous ammonia at planting time on spring wheat and barley. Agronomy Journal 74:1081-1083.

Varvel, G.E., Anderson, F.N., and Peterson, G.A. 1981. Soil test correlation problems with two phosphorus methods on similar soils. Agronomy Journal 73:516-520.

Peterson, G.A., Anderson, F.N., Varvel, G.E., and Olson, R.A. 1979. Uptake of ¹⁵N-labelled nitrate by sugar beets from depths greater than 180 cm. Agronomy Journal 71:371-372.

Varvel, G.E., Peterson, G.A., and Anderson, F.N. 1976. A revised method for determining phosphate-phosphorus levels in sugar beet leaf petioles. Journal of the American Society of Sugar Beet Technologists 19:138-142.