In an electrolysis reaction, inert or non-reactive electrodes are placed in water and a
direct electrical current is passed between them. Non-reactive electrodes are typically used
because if they were made of a material that reacts with any of the components of water or
the electricity itself, there wouldn't be a clean split, as other compounds would be formed.
causes changes to occur at the cathode or negative electrode according to Equation 1:
Equation 1: 2H2O - 4e - → O2(gas) + 4H + (Known as oxidation )
At the positive(+) electrode, also known as the anode, electrons (negatively-charged) are
strippedfromwatermolecules,oxygen(O2)isreleased,andprotons(H + ,orhydrogenions)
are formed which travel through the electrolyte (water) towards the negative (-) electrode,
known as the cathode.
hydroxyl ions (OH - ), thus liberating hydrogen gas as shown in Equation 2.
Equation 2: 4H2O + 4e - → 2H2 (gas) + 4OH - (Known as reduction )
The reason this concept is important is because it forms the basis for the application of
electricity to materials containing water. Soil substances that are typically mixed with
pore water include organic and inorganic chemicals and molecules, colloids, and also
Thus, taking these concepts and applying them to soil we end up with reactions called
redox (reduction-oxidation) reactions. In the upcoming subsections, we'll cover how these
reactions affect the soil.
Electrolytes in the Soil
Soils and other plant growth mediums can vary in their innate electrical conductivities
ranging from being not-very-conductive like sand, to being more conductive, like clay
or humus. Most soils are conductive due to the presence of dissolved chemical ions that
include calcium, sodium, potassium, soluble fatty acids, nitrate, phosphate, and chloride
ions. These substances, known as electrolytes, are a class of substances that contain free
ions, which is what makes soils electrically conductive.
In order for soils to be conductive, they need to have a minimal amount of moisture
enough to provide a continuous path for these ions to move. This is essential for plants as