Soil and Plant Analysis

2. Electrical conductivity method

This method is based upon the changes in electrical conductivity with changes in soil moisture. Gypsum blocks inside of which two electrodes at a definite distance apart are used in this method. These blocks require previous calibration for uniformity. The blocks are buried in the soil at desired depths and the conductivity across the electrodes measured with a modified Wheatstone bridge. These electrical measurements are affected by salt concentration in the soil solution and are not very helpful in soils with high salt contents.

Advantages

• Inexpensive

Disadvantages

• Each block requires individual calibration
• Calibration changes with time
• Life of device limited
• Provides inaccurate measurements