Irrometer Sensor operation description
The Irrometer sensor works a little different then the other two sensors on this project and therefore the chart reads a little different. This is because it measures soil tension, not the percentage of moisture.
This is another way to measure soil moisture. It is called a soil water tension indicator. Soil water tension is the measure of how strongly water is held in the soil. This indicates how hard the plant must work to extract water from the soil, the drier the soil, the higher the tension. Proper irrigation scheduling keeps the soil water tension below the stress level for the plant material.