General Considerations for Geophysical Methods Applied to Agriculture - Agricultural Geophysics - page 10

tAble 1.1
potential Agricultural Applications for Resistivity, electromagnetic Induction,
and Ground-penetrating Radar Methods

Geophysical Method Agricultural Application literature Source

Resistivity Soil drainage class mapping Kravchenko et al., 2002

Electromagnetic
induction

Determining clay-pan depth Doolittle et al., 1994

Electromagnetic
induction

Estimation of herbicide partition coefficients
in soil

Jaynes et al., 1995a

Electromagnetic
induction

Mapping of flood deposited sand depths on
farmland adjacent to the Missouri River

Kitchen et al., 1996

Electromagnetic
induction

Soil nutrient monitoring from manure
applications

Eigenberg and Nienaber, 1998

Ground-penetrating radar Quality/efficiency improvement and updating

of U.S. Department of Agriculture/Natural
Resources Conservation Service (USDA/
NRCS) soil surveys

Doolittle, 1987; Schellentrager et al., 1988

Ground-penetrating radar Measurement of microvariability in soil

profile horizon depths

Collins and Doolittle, 1987

Ground-penetrating radar Bedrock depth determination in glaciated

landscape with thin soil cover

Collins et al., 1989

Ground-penetrating radar Plant root biomass surveying Butnor et al., 2003; Konstantinovic et al.,

2007; Wöckel, et al., 2006

Ground-penetrating radar Identification of subsurface flow pathways Freeland et al., 2006; Gish et al., 2002

Ground-penetrating radar Farm field and golf course drainage pipe

detection

Allred et al., 2005a; Boniak et al., 2002;
Chow and Rees, 1989

Resistivity and
electromagnetic
induction

Soil salinity assessment Doolittle et al., 2001; Hendrickx et al., 1992;

Rhoades and Ingvalson, 1971; Rhoades
et al., 1989; Shea and Luthin, 1961

Resistivity and
electromagnetic
induction

Delineation of spatial changes in soil
properties

Allred et al., 2005b; Banton et al., 1997;
Carroll and Oliver, 2005; Johnson et al.,
2001; Lund et al., 1999

Resistivity, electromag-
netic induction, and
ground-penetrating
radar

Soil water content determination Grote at al., 2003; Huisman et al., 2003;

Kirkham and Taylor, 1949; Lunt et al.,
2005; McCorkle, 1931; Sheets and
Hendrickx, 1995

Substantial efforts have been devoted toward evaluating the capabilities of resistivity and elec-
tromagnetic induction methods for soil salinity assessment. The standard laboratory technique for
determining salinity involves measuring the electrical conductivity of water extracted from a soil
sample saturated paste (Smedema et al., 2004). The soil salinity obtained by the electrical con-
ductivity of a saturated paste extract is designated EC e . Resistivity and electromagnetic induction
methods are used in the field to measure an “apparent” electrical conductivity for a bulk volume of
soil beneath the surface, and this apparent electrical conductivity is designated EC a . By incorporat-
ing various soil moisture, soil density, and soil textural parameters, EC e can be calculated from EC a
(Rhoades et al., 1989, 1990). Discussions regarding the impact of soil conditions and soil properties
on EC a can be found in Chapters 2, 4, and 5. With the protocols now available for calculating EC e
from EC a , resistivity and electromagnetic induction methods are indeed valuable tools for monitor-
ing soil salinity levels in an agricultural field.
Precision agriculture is a growing trend combining geospatial data sets, state-of-the-art farm
equipment technology, GIS, and GPS receivers to support spatially variable field application of