Soil Moisture Meters

Written by
Steve Troy
Published on
April 1, 2022 3:50:49 PM PDT April 1, 2022 3:50:49 PM PDTst, April 1, 2022 3:50:49 PM PDT

Soil Moisture Meters

Take some of the guesswork out of irrigation design, installation, and maintenance

What is the importance of Soil Moisture and when to use which kind of moisture meter? The amount of moisture or soil water is important to know because:

  • Soil water serves as a solvent and carrier of food nutrients for plant growth
  • The yield of a crop is more often determined by the amount of water available rather than the deficiency of other food nutrients
  • Soil water acts as a nutrient itself
  • Soil water regulates soil temperature
  • Soil forming processes and weathering depend on water
  • Microorganisms require water for their metabolic activities
  • Soil water helps in chemical and biological activities of soil
  • It is a principal constituent of the growing plant
  • Water is essential for photosynthesis

The fact that soils hold water (moisture) is due to their colloidal properties and aggregation qualities. The water is held on the surface of the colloids and other particles and in the pores. The forces responsible for retention of water in the soil after the drainage has stopped are due to surface tension and surface attraction and are called surface moisture tension. This refers to the energy concept in moisture retention relationships. The force with which water is held is also termed as suction.

Types and Uses

Soil Moisture Meters

Although good moisture levels in the soil help determine plant health, many still rely on just guesswork. And as the best moisture level constantly changes based on temperature, plant size, rain, and many other factors; guessing becomes less and less helpful. Timers can help but irrigation systems based on timers rarely keep soil in that ideal moisture range — not too wet or too dry. The cheap, c. $10 moisture meters can give you a very rough idea but readings stay far from accurate and easily break.

Volumetric Meters

Watermark Digital Meter

This kind of meter estimates the volume of water content. Less expensive and more convenient in some ways, they need to be calibrated to take into account temperature, soil type, and conductivity. They read the percentages of moisture.


Digital Moisture Meter

Tensiometers measure water potential, soil moisture tension. They take a little longer to give information than Volumetric Meters but often give more accurate information in determining when and how much to water. They give readings in mBar, psi, cBar, kPa. 1 bar = 1000 mBar (millibar)

Pump System Meters

Liquid Filled 100 PSI Pressure Gauge

Meters for pumping systems confirm that the system is working properly as well as indicating and helping to diagnose problems. A meter before and one after a filtration system indicates when the filters need to be replaced or cleaned. Generally when the pressure after the filters drops below the pressure reading before the filters.

Root Demand GrowStream Systems

Hose Thread Fitting Kit

These root demand systems give a range of water flows based on the pressure and work best in the 1 to 3 psi range (should not be over 8 psi). Our End Cap Meters make it easy to check pressure at the end of lines to make sure not too high and to help adjust moisture levels.

Remote Read-and-Control meters

Watermark Monitor

High - end meters (both the most expensive and most useful) sense moisture and send the readings to a remote cell phone and/or computer. Some of these can automatically start and stop watering cycles based on this information.