Frequently Asked Questions
Soil Moisture Sensor
- TEROS 21 - Water potential - Soil Moisture Sensor - GENERAL - T8 Tensiometer - T4 Tensiometer - T5 Tensiometer How can you measure kPa or MPa? And what tools can you use for container production?
kPa and MPa are really just a preference. You convert between the two by moving the decimal point. In containers, you can use tensiometers which are highly accurate in the wet range but not in the dry range. Matric potential sensors such as the TEROS 21 also work well. They aren’t as accurate as a tensiometer in the wet end, but they give you a better range and require less maintenance.
- Soil Moisture Sensor - TEROS 11 - Volumetric Water Content - TEROS 12 - GENERAL - TEROS What tools can I use to measure soil moisture along a soil profile of 40cm depth?
- Soil Moisture Sensor - ECH2O 5TE - Volumetric Water Content - TEROS 12 - GENERAL - GS3 What will measuring electrical conductivity give you a metric of versus VWC?
EC can give you the solute concentration of the soil, but is trickier to interpret than VWC since the VWC can be a confounding variable.
- TEROS 21 - Water potential - Soil Moisture Sensor - TEROS 11 - Volumetric Water Content - TEROS 12 - GENERAL - GS3 - TEROS What are important considerations when thinking about measuring water content and water potential in peatlands (with organic soils)?
Variability of your substrate is a big one. There is a lot of variability in soils as well, but we have better mechanisms to capture and account for variability in mineral soils. Good substrate-to-sensor contact is critical and trickier to accomplish (good installation), but it is achievable. You will most likely require a custom calibration for water content.
- Soil Moisture Sensor - ECH2O 5TE - TEROS 11 - ECH2O 5TM - Volumetric Water Content - TEROS 12 - GENERAL - ECH2O EC-5 - TEROS What is the difference between the FDR method and the capacitance method of VWC measurement? Are they the same?
They are technically not the same. For the strictest technical accuracy, FDR makes a frequency scan and capacitance measures the charge time of a capacitor. From a practical standpoint there is little difference in the performance.
- TEROS 21 - Water potential - Soil Moisture Sensor - TEROS 11 - Volumetric Water Content - TEROS 12 - GENERAL - TEROS Would you agree that with the impact of soil moisture on the atmosphere, measuring water content alone is not enough?
It depends on your specific goals. If you are studying the impact of soil water on atmospheric impact then you would need water potential. There are plenty of cases where water content alone is sufficient if you also have information about your soil.
- TEROS 21 - Soil Moisture Sensor - GENERAL - TEROS If I use the TEROS 21 to measure soil water potential when planning irrigation, do I need to know the soil type?
No. With the TEROS 21 you just need to know the matric potential limits of your plants, and you do not need to worry about soil type.
- TEROS 21 - Water potential - Soil Moisture Sensor - WP4C - HYPROP - GENERAL What is matric potential?
Matric potential is the force that would need to be exerted to move a water molecule from the surface of a soil particle. For example, a matric potential of -100 kPa would require a force of -101 kPa to pull that water molecule off of the soil particle. It is one component of the total water potential. Learn more about the different components of water potential here.
- Soil Moisture Sensor - ECH2O 5TE - GS3 Can your 5TE or GS3 tell me the soil salinity or the pore water EC?
Our sensors measure bulk EC, not soil salinity or pore water EC. Pore water EC can be derived from bulk EC using various models, including the Hillhorst model. This is described more in our application note about soil EC.
- Soil Moisture Sensor - GENERAL Why doesn’t my soil moisture sensor read 100% VWC in pure water?
Testing your sensor in water can be a great quick check for basic sensor function, but it is a poor test for accuracy. The calibration of all METER soil moisture sensors is optimized for 0 – 50% volumetric water content (VWC), the usual range of soil water content.
Water will tell you if a sensor responds to a change in water content. But the reading itself will vary. Please contact email@example.com for recommendations to test the absolute accuracy of your sensors.
- Soil Moisture Sensor - GENERAL What does my soil moisture value in a frozen soil mean?
Volumetric water content (VWC) from a frozen soil will look much like dry soil. Your sensor will carry on merrily, but you will not see any change in water content until you start to get liquid water near the sensor again.