Sugarcane Farming, also known as Reed Farming, is a way to quickly destroy a large number of Sugar Canes at one time.
Piston method
This method uses pistons to push the canes into water canals which deliver the items into a single collection point. By using this method, replanting sugar canes isn't needed. Example of a simple sugar cane farm can be found here (where?).
If you wish for this to be completely automated, you can use a redstone clock to make the pistons pulse repeatedly. However, this method will get you only one cane at a time in a somewhat inconsistent fashion. If you wish to harvest all of the canes simultaneously you can simply wire a button or lever to the pistons.
Water flow sugar cane farm method
This method is outdated with 1.7, but can still be used if you do not have pistons available. It uses redstone to update sugarcane that is no longer next to water to break it. You will need 10 sugarcane, 10 redstone dust, 1 water bucket, 1 button (or lever), and at least 20 solid blocks. This design produces 20 sugarcane per harvest, but you can modify it to produce more.
- Sugarcane Farm1.png
Dig 2 trenches with a length of 7 blocks, 3 blocks apart
- Sugarcane Farm2.png
Then build a small stair like structure at the start, with one block in the middle
- Sugarcane Farm3.png
Next, build a doughnut like structure one block above
- Sugarcane Farm4.png
Then fill the hole with water
- Sugarcane Farm5.png
Plant the sugarcane next to the water
- Sugarcane Farm6.png
Then dig three block through under the stairs
- Sugarcane Farm7.png
On the other side, dig two blocks connecting to the other three you just dug
- Sugarcane Farm8.png
Then run redstone down between the sugarcane and on the blocks you dug
- Sugarcane Farm9.png
Finish the redstone on the other side
- Sugarcane Farm10.png
Add a button, or lever
- Sugarcane Farm11.png
Then wait for the sugarcane to grow to full size
- Sugarcane Farm12.png
Then place a block under the water (careful not to put it on the source)
- Sugarcane Farm13.png
Then push the button when the water has drained out
- Sugarcane Farm14.png
All the sugarcanes should break (collect them)
- Sugarcane Farm15.png
Then break the block under the water to let it flow again
- Sugarcane Farm16.png
Last, replant the sugarcane and repeat as many times as you like