Methods to Measure Soil Moisture
Soil moisture monitoring can give a homeowner more knowledge on about his or her yard and how a landscape can become more water-wise. This article will outline some of the general methods and instrumentation used when measuring soil moisture.
Volumetric Field Methods- these types of testing estimate water volume from a sample of undisturbed soil.
- Neutron Moderation- Radioactive neutrons collide with soil particles to give a proportional count of the volume of water present.
- Advantages: accurate, inexpensive, not affected by salinity or air gaps
- Disadvantages: safety hazard (radiation), requires certified personnel
- Frequency Domain- Uses electrical current to measure soil moisture
- Advantages: accurate, reads in high salinity, relatively inexpensive
- Disadvantages: sensitive to air gaps and temperature, small sensing area
- Heat Dissipation- thermal conductivity is used to measure moisture in the soil
- Advantages: wide measurement, no maintenance, not affected by salinity
- Disadvantages: sophisticated controller needed, slow reaction time
- Dielectric Method-Electromagnetic waves are used to measure soil saturation
- Advantages: accurate, minimal soil disturbance, soil calibration not usually required
- Disadvantages: expensive, sensitive to salinity
|Neutron moisture meter/probe. Photo credit: Texas AgriLife Research & Extension Center at San Angelo|
There are many other ways to measure soil moisture. It is important to gain as much information as possible about your yard to maximize water efficiency.
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