Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 10/15/2008
Publication Date: 8/16/2011
Citation: Allred, B.J., Butnor, J., Corwin, D.L., Eigenberg, R.A., Farahani, H., Johnsen, K., Lambot, S., McInnis, D., Pettinelli, E., Samuelson, L., Woodbury, B.L. 2011. Agricultural Geophysics. In: Turk, A.S., Hocaoglu, A.K., Vertiy. A.A. (eds.) Subsurface Sensing. John Wiley & Sons, Inc., Australia. 618-643.
Technical Abstract: The four geophysical methods predominantly used for agricultural purposes are resistivity, electromagnetic induction, ground penetrating radar (GPR), and time domain reflectometry (TDR). Resistivity and electromagnetic induction methods are typically employed to map lateral variations of apparent soil electrical conductivity (ECa) within an agricultural field, which in turn often reflect horizontal soil property spatial patterns. Applications of GPR in agriculture are widespread, ranging from drainage pipe detection, to tree root biomass determination, to soil moisture mapping. The TDR systems presently available can be used to measure soil water content and ECa. The geophysical investigation depth for agricultural applications is typically much smaller than the geophysical investigation depths needed for environmental or engineering site evaluations. Accordingly, agricultural geophysics tends to be largely focused on the soil profile within 2 meters of the ground surface, which includes the entire crop root zone. With respect to agricultural geophysics applications, this extremely shallow 2 meter depth of interest is certainly an advantage, since most geophysical methods presently available have investigation depth capabilities that far exceed 2 meters. However, there are complexities associated with agriculture geophysics not typically encountered with the application of geophysical methods to other industries or disciplines, and these include transient field conditions, small-scale spatial variability, and the common need to resolve small features/objects. New applications of geophysics to agriculture continue to be discovered, and as such, it is expected that geophysics will become a more important tool for agricultural information acquisition in the future.