Gravimetric water content (GWC) is the most accurate measure of soil moisture. It involves physically drying the soil sample and measuring the mass of water lost. GWC is typically expressed as a percentage of the dry soil mass.
Volumetric water content (VWC) is another common measure of soil moisture. It represents the volume of water in a soil sample relative to the total volume of the sample. VWC is usually expressed as a percentage or as a decimal fraction.
Water potential (Ψ) is a measure of the energy required by a plant to extract water from the soil. It reflects the relative ease with which water moves through the soil. Water potential can be measured using tensiometers or psychrometers.
Electrical conductivity (EC) measures the ability of soil to conduct electricity. It is influenced by the amount of dissolved salts in the soil, which can vary with soil moisture. EC can be measured using conductivity probes.
Neutron scattering is a non-destructive technique that uses neutrons to measure soil moisture. It is often used for measuring large soil volumes or in-situ measurements.
The choice of the best measure of soil moisture depends on several factors:
Measuring soil moisture is essential for managing soil and water resources. The best measure depends on the specific application and the available resources. By considering the factors discussed above, decision-makers can choose the most appropriate method to accurately assess soil moisture conditions.