Moisture sensor

This is a simple sensor to measure the moisture in soil. I made it for a small plant watering project. The moisture is measured by the changing capacity of the two concentric coils which are made out of enameled copper wire. In addition there are two unisolated wires made out of stainless steal to measure the ohmic value of the soil to measure the change of minerals in the soil.
The whole sensor is then casted into cement to ensure a homogenic filling of the coils and to prevent roots from gr