With hopes of reinventing the way food is grown, Rory Aronson has developed humanity’s first open-source CNC farming machine. The FarmBot Genesis — which will begin taking pre-orders in July — is capable of planting seeds and then watering them precisely.
— https://blog.arduino.cc/2016/06/07/farmbot-is-an-open-source-cnc-farming-machine/

Arduino.cc have a nice write up of what looks to be a nice open source project; FarmBot Genesis