Agriculture Reference
In-Depth Information
Chapter 5
Sensing of Natural Soil Properties
Hermann J. Heege
Abstract
Site-specific sensing of varying natural soil properties is a prerequisite
for an adequate control of many field operations.
Topography can be mapped rather easily as a byproduct of other farming opera-
tions by means of RTK-GPS. Information about clay, moisture and salinity of soils
in a combined mode can be obtained via electric conductivity sensing. In humid
areas, salinity can be left out. So here the electric conductivity is defined mainly by
a combination of clay- and water content of the soil. The combined effect of these
factors is well related to the yield potential of soils. Hence in humid regions, electric
conductivity sensing can supply information that is needed for the control of farm
operations according to yield expectations.
Electric conductivity sensing is based on soil volumes that may include the top-
soil as well as the subsoil. In contrast to this, the reflectance of visible or infrared
light senses only soil surfaces and thus may be less representative. Yet reflectance
sensing might supply signals simultaneously about several soil properties such as
texture, carbon content, cation-exchange-capacity and water content.
Keywords
Capacitance • Electrical-conductivity • Permittivity • Reflectance •
Surface-sensing • Topography • Volume-sensing
