The Wetting Front Detector (WFD) records the depth of infiltration of irrigation water. The WFD is buried in the root zone. When the infiltrating water goes past the WFD, it captures a water sample and pops up a magnetically latched indicator.
The WFD stores this soil water sample for later analysis. The water sample is removed using a syringe. All dissolved salts are measured using a VIA Electrical Conductivity (EC) meter. Nitrate, which is the most difficult nutrient to manage in irrigation, is measured with colour strips.
WFDs are used as irrigation management tools, particularly to identify over-irrigation and water logging. However, their main use is for solute monitoring in conjunction with the VIA EC meter and nitrate test strips.