Minecraft wiki entry for Sugar_cane_farming, associated text: It is not difficult to connect this with a piston to make it more automatic. However, since pistons cannot push and retract as quickly as the observer clock, it may be desirable to use a different redstone clock. Additionally, a single hopper may not be able to keep up with the large amount of sugar cane, so multiple hoppers or a slower clock should be used. Ideally, a 4 gametick delay clock should be used instead of an observer clock. Even more ideal is a 2 gametick alternating dispenser bonemeal system with a ravager in a minecart to break the top 2 sugarcane blocks.