As I said in the previous comment, right now, high-value crop growers like wine grape growers pay $700-$1000 or more per site (including reader/comms module and sensors), and generally only install one monitoring point per block (I have a system running at one of Australia's top boutique/biodynamic wine makers and at current prices he can only cost-justify having one 10 monitoring sites over his 70 acres of vines).
So, whatever we can do to drive down the cost to $20 or less should deliver big wins.
> Maybe talk to someone at Nordic
Yep, we're working with hardware engineers who are well connected to people at Nordic.
But the economics of farming in the Eyre Peninsula is quite different and they really have a water problem. From a food PoV these are the people we really need to help.
(I have family in both, not to mention in laws in Germany who also have a water problem...getting rid of it!)
It's an interesting problem and I am sure reference designs already exist. Maybe talk to someone at Nordic.