Rachio should develop wireless moisture and PH level sensors. The sensors can be used to determine if the yard needs to be watered or not. You have have several sensors around the yard that talk to the Racho controller.
The other sensor is PH level sensor. This could help in determining if you need to add lime or sulpher. If your soil tests indicate too much acidity, then you would need to add lime to increase the alkalinity to reach your target pH. If your soil test indicates too much alkalinity, then you would add sulfur to increase soil acidity to reach your target pH.
Just some thoughts!