The soil water content measured by ML3 within one small locality can be affected by:
- Variations in soil density and composition
- Stones close to the rods
- Roots (either nearby or pierced by the rods)
- Earth worm holes or mole holes
- Subsoil drainage
- Small scale variability in transpiration and evaporation losses
Take this into account when deciding on the number of probes to be used at any particular location. If the soil is very heterogeneous, it is necessary to take measurements from at least 3 closely spaced locations.