I have another idea - since we are in a severe drought here in southern California and people still water golf courses and what not like crazy, how about a sensor device that you can plug into the ground that tells you a) the moisture content and b) when the next watering should take place.
Then again, maybe there is something like this already out there and I just
don't know it.
Or some freeze dried compound that can be put around trees, shrubs and into the grass that converts into liquid and waters on a time release basis as needed. I guess that would be more a project for a chemist.