Agriculture Reference
In-Depth Information
Chapter 5: Electrical Properties of Soils
In this chapter we're going to jump into the science of soils from an electrical perspective.
What this means is that we're primarily going to focus on soils as an electrolytic medium,
or in other words, its ability to conduct electricity.
Due to the results of the soil-forming process, the distribution and movement of electrical
charges in soils can vary quite drastically, usually due to the following properties:
• The types & charges of materials
• Moisture levels
• Cation Exchange Capacity (also known as the CEC)
• And more.
Since ionic compounds present in soil tend to clump together due to their intrinsically
chargednature(sincepositivechargedparticlestendtobeelectricallyattractedtonegatively
chargedones),soilaggregatesofvaryingnetchargewillcollectinvariousregionsofagiven
soil mass. The difference in charge between any two or more regions of the soil will result
in a voltage difference between those regions (albeit a very small one). Any time a voltage
is present within the soil, it implies that there will also be an electric field present, too.
Chemical properties such as humus content, CEC, mineral composition, and the amount
of soluble salts all have an influence on how ions are exchanged within soils. Nutrient
availability, pH and the degree of how easily ions are adsorbed and desorbed from soil
particles determine the overall functionality of a soil with regards to its ability to support
life.
Electrical Resistivity and Conductivity
Electrical resistivity is a physical property that describes how well a particular material
resists the flow of electric current through it. According to Ohm's Law, Voltage(V)=
Current(I) x Resistance(R). As shown in the diagram below, the amount of resistance of a
particular material is based on its geometry and volume.
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