Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: September 23, 2005
Publication Date: June 10, 2008
Citation: Eigenberg, R.A., Nienaber, J.A., Woodbury, B.L., Ferguson, R.B. 2008. Four-year summary of the use of soil conductivity as a measure of soil and crop status. In: Allred, B., Daniels, J.J., Ehsani, M.R. editors. Handbook of Agricultural Geophysics. Vol. 124. Boca Raton, FL: CRC Press. p. 273-280. Technical Abstract: Soil nutrient N needs for crop production can be met with animal manure; however, management of animal manure to match crop needs throughout the crop growing season can be a challenge. This study was conducted to examine changes in electromagnetic induction (EMI) soil conductivity and available N levels over four growing seasons in relation to manure/compost application and use of a green winter cover crop. A series (weekly surveys) of soil conductivity maps of a research cornfield were generated using global positioning system (GPS) and EMI methods with simultaneous soil samples. The study site was treated over a ten-year period with a winter wheat (Secale cereale L.) winter cover crop and no cover crop. The cornfield research site was split for sub-treatments of manure and compost at rates matching either the P or the N requirements of silage corn (Zea mays L.). Sequential measurement of profile weighted soil electrical conductivity (ECa) was effective in identifying the dynamic changes in plant-available soil N, as affected by animal manure and N fertilizer treatments, during four corn growing seasons. This method also clearly identified the effectiveness of cover crops in minimizing levels of available soil N before and after the corn growing season, when nitrate is most subject to loss. The EMI method for assessing soil condition provides insights into the dynamics of available N transformations that are supported by soil chemical analyses. This real-time monitoring approach could also be useful to farmers in enhancing N use efficiencies of crop management systems, and in minimizing N losses to the environment.