It probably would save on watering – the ‘industry standard’ ETO method uses soil moisture as a key part of its algorithm.
How would you propose to get soil moisture data into OSPi? Would you want to have a soil sensor directly provide it over a GPIO pin? Or would you get soil moisture data from a network device? Or from a station on the internet? Would you have one sensor or multiple?
I personally backed the Edyn project in order to do just this – but obviously that device won’t arrive until 2015 (which is a crazy long time but don’t get me started.)
Scott