Green Fingers! what a great expression..
This is Siouxsie and the Banshees, from a great 1980s album..
Here is a water-saving passive radar idea..
Just for future reference, one can determine how much water is in soil by comparing the reflected signal from GPS satellites by polarization. Reflection will reverse the polarization. Two good circular polarized directional antennas will allow you to ascertain which earth in a fairly large area is damp, and which is dy by the ratio. One could use two conical log spirals of identical size on a tower to cover a fairly large plot. And possibly save a lot of water. Modern dromes can use RTKlib for precise drone positioning and carry a moisture sensor over a considerable area. The presence of precisely located GNSS signals lends itself to a system to conserve water 's automation. Clearly this is an idea whose time has come because of the maturing on several relevant technologies and their sudden low cost due to mass production.
Receiver could be stationary on a tower or carried by a drone. (would have to be designed to be light, I have an antenna that would work for this, it is made around a cheap styrofoam cone.
There is a marked difference between the ratio of LHCP and RHCP that depends utterly on the water in the soil.
One will need a well made dual polarization conical log spiral antenna such as the one described by Dyson. It should be made by wrapping a floral art cone with the right copper shapes as described by Dyson. One needs to overlay four windings two in the LHCP two in the RHCP direction. This makes a very useful antenna for a number of applications. Due to the phase center of both antennas being nearly identical. Such an antenna would be useful for ground penetrating radar as well, which this idea kind of is.. a poor mans ground penetrating passive radar based on the free GNSS signals.
Antenna looks like a pointy barber pole, a bit. Its fed from the front tip which is the area of directionality. It functions like an LPDA except its circular. Such an antenna was made once by the University of Illinois's famous ECE department.
Since one knows quite precisely where the GPS satellites are, (the signal source to be reflected) - A log spiral is an ideal GNSS antenna. In fact the GPS satellites own antennas are conical log spirals.
Reflections from well-hydrated soil will predominate more and more LHCP. I will have to hunt the reference down, this was the subject of a paper in the GNSS literature from some years ago.
Could be useful in saving lots of water, I bet.