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. Additional research activities include utilization of long-term field experiments with multiple management scenarios (tillage, N fertilizer, cropping systems, corn residue removal) to determine their effects on crop production and soil properties, with emphasis on soil organic matter levels.
Cambardella, C.A., Johnson J.M.F., and Varvel, G.E. 2012. Soil Carbon Sequestration in Central USA Agroecosystems. In Liebig, M.A., A.J. Franzluebbers, and R.F. Follett (Eds.) Managing agricultural greenhouse gases: Coordinated agricultural research through GRACEnet to address our changing climate. Elsevier Publ., San Diego, CA. p. 41-58.
Vogel, K.P., Follett, R.F., Varvel, G.E., Mitchell, R.B., and Kimble, J.M. 2012. Soil carbon sequestration by maize and switchgrass grown for bioenergy. BioEnergy Research. 2012, DOI: 10.1007/s12155-012-9198-y.
Wienhold, B.J., Varvel, G.E., and Jin, V.L. 2011. Corn cob residue carbon and nutrient dynamics during decomposition. Agronomy Journal 103:1192-1197.
Varvel, G.E., and Wilhelm, W.W. 2011. No-tillage increases soil profile carbon and nitrogen under long-term rainfed cropping systems. Soil & Tillage Research 114:28-36. http://hdl.handle.net/10113/49806
Karlen, D.L. Varvel, G.E., Johnson, J.M-F., Baker, J.M., Osborne, S.L., Novak, J.M., Adler, P.R., Roth, G.W. and Birrell, S.J. 2011. Monitoring Soil Quality to Assess the Sustainability of Harvesting Corn Stover. Agron. J. 103:288-295.
Mitchell, R.B., Wallace, L., Wilhelm, W.W., Varvel, G.E., and Wienhold, B.J. 2010. Grasslands, Rangelands, and Agricultural Systems. Ecological Applications. www.esa.org/biofuelsreports
Varvel, G.E., and Wilhelm, W.W. 2010. Long-term Soil Organic Carbon as Affected by Tillage and Cropping Systems. Soil Science Society of America Journal. 74:915-921. http://hdl.handle.net/10113/42536
Wilhelm, Wally W., Hess, J. Richard, Karlen, Douglas L., Johnson, Jane M.F., Muth, David J., Baker, John M., Gollany, Hero T., Novak, Jeff M., Stott, Diane E., and Varvel, Gary E. 2010. Review: Balancing limiting factors & economic drivers for sustainable Midwestern us agricultural residue feedstock supplies. Industrial Biotechnology 6(5): 271-287.
Wienhold, B.J., Varvel, G.E., and Wilhelm, W.W. 2009. Container and Installation Time Effects on Soil Moisture and Temperature and Inorganic Nitrogen Retention for an In Situ Mineralization Method. Communications in Soil Science and Plant Analayses. 40:2044-2057. http://hdl.handle.net/10113/32342
Follett, Ronald F., Varvel, Gary E., Kimble, John M., and Vogel, Ken P. No-Till Corn after Bromegrass: Effect on Soil C and Soil Aggregates. Agronomy Journal. 101:261-268. 2009.
Varvel, G.E., and Wilhelm, W.W. 2008. Corn Cob Biomass Production in the Western Corn Belt. Bioenergy Research. 1:223-228.
Varvel, G.E., and Wilhelm, W.W. 2008. Soil Carbon Levels in Irrigated Western Corn Belt Rotations. Agronomy Journal 100:1180-1184. http://hdl.handle.net/10113/18315
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
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.
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
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
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
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.
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
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/10113/16822
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/10113/16821
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.
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/10113/17398
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
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).
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/10113/16820
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/10113/16816
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/10113/17395
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/10113/17394
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.