DEGREES:
- B.A., Chemistry and Mathematics, Chadron State College, 1971
- PhD., Soil Fertility and Chemistry, University of Nebraska, 1977
RESEARCH INTERESTS:
Soil and crop management, crop rotations, soil fertility, site specific farming.
MAJOR PROJECT ACTIVITIES:
My project activities 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. My research is also extensively involved with the development of decision tools (remote sensing, etc.) for use in precision agriculture.
SELECTED PUBLICATIONS:
· Varvel, G. E. 1995. Precipitation use efficiency of soybean and grain sorghum in monoculture and rotation systems. Soil Sci. Soc. Am. J. 59:527-531.
· 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. Agron. J. 88:1-5.
· Blackmer, T. M., Schepers, J. S., Varvel, G. E., and Meyer, G. E. 1996. Analyses of aerial photography for nitrogen stress within corn fields. Agron. J. 88:729-733.
· Varvel, G. E., Schepers, J. S., and Francis, D. D. 1997. Chlorophyll meter readings and stalk nitrate as complementary nitrogen indices for residual nitrogen. J. Prod.Agric. 10:147-151.
· Varvel, G. E., Schepers, J. S., and Francis, D. D. 1997. Ability for in-season correction of nitrogen deficiency using chlorophyll meters. Soil Sci. Soc. Amer. J. 59:1233-1239.
· Eghball, B. and Varvel, G. E. 1997. Fractal analysis of temporal yield variability of crop sequences: implications for site-specific management. Agron.J. 89:851-855.
· Yamoah, C. F., Francis, C. A., Varvel, G. E., and Waltman, W. J. 1998. Weather and management impact on crop yield variability in rotations. J. Prod. Agric. 11:219-225.
· 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.
· Wilhelm, W. W., Liebig, M. A., Varvel, G. E., and Blackmer, T. M. 1999. Midseason stalk breakage in corn as affected by crop rotation, hybrid, and N-fertilizer rate. Agron. J. 91:160-165.
· 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.
· Varvel, G. E. 2000. Crop rotation and nitrogen effects on normalized grain yields in a long-term study. Agron. J. 92:938-941. 2000.
· Liebig, Mark A., Varvel, Gary E., and Doran, John W. 2001. A simple performance-based index for assessing multiple agroecosystem functions. Agron. J. 93:
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