Electrical conductivity is the ratio of the electric current density to the electric field in a material. Electrical conductivity measurements are applied in studies of both agricultural and engineering problems. Soil scientists use such measurements mainly to characterize the salt contents of soil, irrigation or drainage waters, and occasionally as an indirect way of determining soil water content.
The electrical conductivity, or specific electrical conductance, of a solution is the reciprocal value of its electrical resistivity. Electrical resistance R (ohms) is directly proportional to the distance L (cm) between two parallel electrodes immersed in a solution or soil extract and inversely proportional to the cross‐sectional area A (cm 2) of the material (solution) between the electrodes. Thus R = rL/A, where r is a proportionality constant known as the electrical resistivity. The units for electrical resistivity (r) are ohm‐cm. The electrical resistance (R) is expressed in ohms;...
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