The Irrigation Water Management Society
Certified Site Water Planner (CSWP)
How to understand the soil moisture data
Below is a sample graph that we display on the site. The green variable line is a sensor at 4" depth. The red variable line is at 8" depth. These lines show the soil moisture as a percentage. This is read on the left side of the chart.
The green horizontal line is approximate field capacity. This means that the soil is full of water without being over watered. This is the ideal condition for the plants shortly after an irrigation.
The yellow horizontal line shows when one should begin irrigation (again approximately).
The red horizontal line is when the soil is so dry that severe stress will occur with the plants.
The blue bars at the bottom represent when irrigation or rainfall has taken place. One can read the amount on the right side of the chart.
This site is located within 25’ of the Jefferson park weather station if you wish to see more detailed weather data please click here
The real-time soil moisture data can be found by clicking on the links below:
Below each soil moisture graph you will see another graph that looks like the one below. This is an ET (evapotranspiration) graph for the same period at the same site. It is displayed in inches which can be read on the left side of the chart.