With the coming summer heat we've been doing some tweaking to our open source Smallholder Sensor Framework code including our automated spray controller. We use this device to keep our chickens cool in the summer, and when there ware only two zones we needed to manage it was OK to hard-code the sensor to pump associations. As luck would have it a sensor broke and we also needed to extend coverage, so I rewrote the code and now nearly everything is configurable in the field with a serial connection. You can now scan the network for sensors, and associate sensors with pump/solenoids, along with setting the trigger point. There is also an extensive debug and test mode available.
Check out the code on GitHub