All,
I am debating to solution an multi valve 24 v irrigation control, using a servo pwn relay and the auxiliary servo capabilities( I once had a spinning propeller on the servo to scare the birds when motion was detected) I currently have one 24 volt set up for the solenoid valve on a single controller but no I want to increase water pressure and segment it 3 ways. ( yes I can run long wires to my rachio system but I never like to do things a straight forward way. 
… In the drone /robotics world servo relays are common( such as in Ukraine to release a motor round!) so I figured it could work . Let me know if you have had any luck with the servo capabilities from the farmduino in this fashion. or tell me run 6 wires of 300feet wire instead. Joe