How do I correctly place the sensor in the soil?

How and where you put the sensor in the soil is important. This will affect the results you will get from the sensors. For irrigation purposes, we have put together a quick guide that may help guide you to finding the right setup for your use case. 

In order to be ready to place the sensor in the ground, we suggest to prepare

  • Sensor(s)

  • A bucket

  • Shovel, earth drill or similar digging tool 

  • Water

Before sensor installation, the Watermark sensor needs a certain preconditioning in water. Once a sensor was out of the soil for two days or more, preconditioning should be performed again. This is done to improve sensor response during the first few irrigations. To correctly set up the sensor, the following steps should be completed: 

During the soaking procedure the whole metal part of the sensor should be covered in water:

For sensor installation, a hole of the required depth needs to be made. Its diameter should slightly exceed the sensor diameter (25mm/1”). Once the hole is prepared, the sensor can be placed.

To place the sensor at the desired depth, keep an eye on the marks you can see on the sensor (see figure 6). You will be able to enter the amount of marks still visible after planting the sensor in our system, this way the system knows how deep the sensor was dug in. If you know the required depth and want to calculate the number of marks that must be visible for the respective depths, see figure 6.

The calculated depth is measured from the center of the watermark sensor to each mark on the shaft of the housing.

Example: If you intend to place the middle of the watermark sensor at 14 cm deth/5.5 inch you need to make sure that the top mark is at soil level (0 visible marks above soil level). If your intention is to place the middle of the sensor at 6.5cm depth (minimal depth) the first mark should be at soil level and 5 additional marks should be visible.

If not desired differently, or not stated otherwise: place the sensors at 14 cm depth.

To finish the physical sensor placement, mud is produced by mixing field soil with water. The space around the sensor is then filled with the mud (see figure 7 & 8). If necessary, some additional soil is added, so that the sensor can not wiggle anymore.

These general rules should be followed when installing a sensor into the ground:

  1. The soil in the area surrounding the sensor should not be excessively compacted/hardened. This can be avoided by digging a hole large enough to easily fit the sensor.

  2. The sensor must have full contact with the surrounding soil, this is very important to make sure the collected data is useful.

Space around the sensor is filled with a soil slurry

Sensor placed in a corn field

Have a question?