|Daniels, Jeffrey - OHIO STATE UNIV.|
|Collins, Mary - UNIV. OF FLORIDA|
|Doolittle, James - USDA/NRCS/NSSC|
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: November 20, 2002
Publication Date: July 16, 2003
Citation: DANIELS, J., ALLRED, B.J., COLLINS, M., DOOLITTLE, J. GEOPHYSICS IN SOIL SCIENCE. LAL. R., EDITOR. MARCEL DEKKER, NEW YORK, NY. ENCYCLOPEDIA OF SOIL SCIENCE. 2003. P. 1-5. Technical Abstract: Geophysics can be defined as the science of measuring physical property changes in the subsurface through the use of instruments located in boreholes, on (or near) the surface, or in the air. The instruments that make these measurements are designed to detect a particular phenomenon caused by a contrast in physical properties. In some cases there is a source of energy that stimulates a detectable physical change in the subsurface that can be detected by some type of detector which is separate from the source of energy. These methods are called active measurements. Other measurements simply detect a change in the natural background, and these methods are called passive measurements. Geophysical methods can be further classified based upon the general category of physical properties that are measured. The general classification includes electrical, seismic, nuclear, potential field, and thermal methods. The application of geophysical methods for agricultural purposes has been steadily growing over the past two decades. The impetus for these developments has been the primary need to improve the efficiency of agricultural processes. These improvements have required an increase in the knowledge of the physical and chemical properties at a given field site. The physical properties of interest include the soil texture, moisture, and density, and the location of drainage pipes in the subsurface. The chemical properties of interest include soluble salts, nutrients, and cation exchange capacity of soils. Electrical and neutron scattering methods have proven the most effective in addressing these problems.