I have a fully populated soil moisture /soil temperature /leaf wetness station. I have used PVC pipe to “plant” my pair of sensors in each the pipes. I used 1.5 inch pipes, ran down the pipe the soil moisture probe leads and the soil temperature leads. You want to have for each soil moisture sensor at temperature probe to get an accurate reading, otherwise the unit will use a default of 74.4F for the temperature which will give inaccurate readings.
Originally I used PVC cement on the pipes but realized that if I needed to pull up the sensors for repairs it would be difficult to unthread the wire leads from the pipes.
Here I also have a soil temperature probe at ground level, not buried. I use that to measure soil surface temperatures . I had an extra ISS board that I replaced the SuperCap sitting around. So I fashioned the probe setup for that.
You will see I have 6 pipes, one of the soil moisture probes went bad and I had to replace it before removing the damaged sensor.
the Leaf wet wetness sensor is on the back side of this unit. Here you can see the wiring jig. I keep the sensors in the ground year round. In the winter , when the soil moisture reading approaches 200, I can see when the ground is frozen and the temperature as well