Earlier today when I was watching Etho's video on water, when we got to the part about reeds, I realized that automatically harvesting reeds could soon be a possibility with the coming pistons and a bit of redstone. The concept is that when reeds have to water adjacent to them, they will still stay planted until a block adjacent to them is updated, something very easily achievable through powering redstone.
The only thing that would needed to be added to an existing reed farm would be a redstone field under the reeds and a piston holding back a water source block as the initial source of water for the entire farm or just a row of reeds. For planting the reeds after a harvest or the initial setup of the farm, the pistons will be unpowered and allowing the water to flow. But when the lever is flipped, the piston will extend and block off the water to the reeds making them viable for auto-harvesting at the update of a block. ( This is where the redstone field comes into play
) A separate wire coming off of the lever would lead to a field of redstone directly underneath the blocks that the reeds are planted on after heading through a slight delay to allow all water left in the farm to clear. Once all the water clears and the redstone turns on, all of the reeds in the farm will be harvested and the lever can be flipped back into the off position allowing for the re-planting of reeds and will cause the water streams to flow to a collection point, bringing all the reeds that landed in the water trenches directly to you. The rest of the reeds will also be harvested when you go back to replant the reeds.
This design has one fatal flaw, the re-planting. Since this contraption breaks all 3 blocks of reeds, the bottom block will have to be replanted manually, a problem non-existent in traditional reed farms. However, the time used re-planting the reeds is most likely overshadowed by the advantage in speed that harvesting every single reed in an extremely short amount of time. This design would be most effective in a large ( and I mean very large ) reed farm which has at least 2 or 3 people to help with replanting.
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