Monday 13 February 2017

Why my soil moisture sensor might be lying to me?

After choosing the type of moisture sensor you are going to invest in, the most crucial thing is to get the installation correct. It goes back to the old adage; rubbish in rubbish out, if you don’t get the installation correct everything that follows will at best be very marginal data.

Most probes are measuring a very small volume of soil within 10-20mm of the sensor itself, so good soil contact is imperative as well as a crop cover around the probe that is representative of the rest of the field being monitored.

If you are looking at installing a probe for next season or looking at maintenance on an existing probe then read on! These few basic does and don’ts will be of good use!


  • Don't leave the excess cables on the ground – it is an accident waiting to happen!
  • Don’t leave exposed cables for wildlife that want to see how tasty it is!
  • Don’t site the probe on a ridge or in a hollow!
  • Don’t site the probe in bare soil. Is there a crop growing over the probe site to give you a true representation of what is happening in the rest of the field? 
  • Don’t site under the fence line
Don't leave cables on the ground

  • Ensure you use good consistency of slurry around the probe to ensure good soil contact.
  • Ensure you know the soil type your moisture sensor is located in and how that compares to the rest of the area you are monitoring.
  • Make sure any tramlines or irrigation tracks miss the probe site by metres rather than millimetres!
  • If your probe is near an electric fence, do ensure any metalwork is earthed.
  • Do install the probe as early in the season as you can, so it has time to bed in and the crop over the top of it time to establish like the rest of the field.
  • Do ensure a competent and trained person installs the probe with the right equipment to do so!
  • If checking an old installation make sure there are no cracks around the probe site, the soil around the probe hasn’t sunk and the wires are in good order.

AquaLINK telemetry unit, away from AquaCheck probe out in the paddock
If you have any doubts about the site or installation of your probe, by installing it as early in the season as you can means that it can be moved and still have the winter to bed in again.
AquaCheck WEB, induvial sensor graph responding to irrigation and rain events.
Monitor your probe data and its response to rain or irrigation events, the beauty of the capacitance probes is that moving them is not an issue.

This article contains information from a post previously written by HydroServices but has been updated to include the experience from the Agri Optics team installing AquaCheck probes.