What Types of Soil Conduct Electricity?

Moisture

• Water conducts electricity exceptionally well. Soils with high water content are better able to conduct electricity than dry soils. Clay and loam soils hold more water for longer periods of time than sandy soils. The reason for this is due to the size and texture of the soil's particles. Sandy soils are made of large particles and are highly porous. Water drains rapidly from these soil types. Clay soil has small particles that are densely stacked against one another. This is what causes clay soils to feel sticky. Clay soils are highly conductive. Loam is a soil type with average sized particles but this soil has high amounts of organic materials. Organic materials provide water-retentive bulk. The retained water and extra moisture helps to make loam a good electrical conductor.

Cation Exchange Capacity

• Cations are electrons that are essential in moving electricity from one place to another. Cations are naturally present in many minerals found in soil. Manganese, potassium, phosphorous and calcium. Other positively charged elements like hydrogen and sodium also increase soil's cation exchange capacity. A high exchange capacity indicates a high electric conductivity potential. Clay particles and organic matter tend to have more of the minerals and elements that contribute to a high cation exchange capacity than do low organic, sandy soils.

Temperature

• Temperature also plays a role in electrical conductivity. When the ground freezes, or comes close to freezing, soil particles move farther apart in much the same way as water particles do when they freeze. Frozen materials expand. When soil particles separate electric conductivity potentials decrease. Some soils, like clay and loam, are better able to retain heat and are therefore better able to conduct electricity, even when temperatures plummet.

Considerations

• Polluted soils often contain high amounts of heavy metals. These metals are left as residue from industrial mining as well as from acid rain. Since metals conduct electricity, soils full of heavy metal residue are capable of conducting electricity. Scientists use sensors to measure electric conductivity and sometimes metallic, underground structures can give false readings.