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I'm building an automated farms for several crops, including wheat.

The farm consists of a long cascade of farm fragments:

Minecraft wheat farm
Seen from side

Currently, I have to manually toggle water off after it reaches the bottom region of the farm.

Is there a way to configure a farm so that the water turns off automatically after the bottom has been reached?

I don't want to use a timer, as I'm looking for a design that is compatible with all tower heights.

  • daylight sensor maybe? – ratchet freak Sep 6 '14 at 0:56
  • Does water block daylight? – Tomáš Zato - Reinstate Monica Sep 6 '14 at 0:59
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    Just an idea that I'm testing currently, but what about a boat pushed on to a pressure plate? The hard part is resetting the design, though. – Proxy Sep 6 '14 at 15:40
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You can detect the presence of a water stream using a boat and a wooden pressure plate. Place a boat on top of a pressure plate, with walls around it so that it cannot be washed away. If water flows under the boat (in the space not occupied by the pressure plate) at at least water level 3 (out of the 8 possible water levels), it will float up and stop activating the pressure plate.

Here is an example mechanism making a clock out of this. The pressure plate controls the piston to turn on the water whenever the boat is on the plate, so it cycles forever (pictured in the middle of shutting off).

Note that in current versions, boats have visual glitches and may appear to escape the box, especially if you put a lid on top. Don't worry about them — the mechanism will still function fine.

In your case, simply make a channel leading the water out of the bottom of your farm and into a detector like the left half of my picture, and you can then send the redstone output up to shut off the water. Of course, for farming you'll want it to not turn the water back on when the bottom dries up, so add a classic flip-flop:

This will turn the water on when the button is pressed, and turn the water off when the boat detects water.

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    Works perfectly. My research shows that certain ammount of water is necessary (I run into issue since I didn't know that originally). – Tomáš Zato - Reinstate Monica Sep 8 '14 at 1:02
  • @TomášZato Thanks for mentioning that! I have updated my answer to include the required water level. – Kevin Reid Sep 8 '14 at 3:47
  • Hello. I just happened to accidentally break the boat after countless days this design was working. I can't seem to be able to place it again... Any idea why? – Tomáš Zato - Reinstate Monica Jun 5 '15 at 15:48
  • @TomášZato Boats are bigger than one block so it may be bumping into the edges. Try placing the boat on the edge and pushing it in, or on a block on top that you then break. – Kevin Reid Jun 5 '15 at 17:09
  • How did you place the boat? I'm using that configuration (creative mode V1.6), and the boat simply won't set anywhere in that four-square on the pressure-plate (it sometimes floated above, but didn't work). I was able to, by opening some walls to the left (and using pressure-plates to block the water), but the boat had a tendency to drift in/out of the walls (maybe graphics glitch, it always returned). But the pressure-plate toggled as it went in and out, got a random active-redstone stream. – Cyclops Jan 2 '17 at 15:55
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I got it almost sorted out :

The daylight sensor is in reversed mode, and the far left comparator is in subtraction mode.

This thing splits the sensor's signal, delays one of them and subtracts the delayed signal from the immediate signal. It is effectively a falling edge detector for daylight. It will periodically output a weak pulse during the afternoon (which is ignored), and a stronger one if light decreases abruptly, which will be the case if you pour water on it. This stronger pulse gets picked up by the repeater and gives you your output.

Limitation : doesn't work around midnight (i.e when the daylight level is 1 or 0).

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  • Nothing : the two-long pipe ensures that the torch's light always overrides daylight (or absence thereof). – Quentin Sep 7 '14 at 10:11
  • Sry have deleted my comment cauze I want to try it out first. comment was: What happens if I use it at night. But if I use a torch nothing is happening. The sensor does not react. – Gerret Sep 7 '14 at 10:16
  • Yep, there seems to be a new bug... I'll tinker with it and edit my post once I have a solution. – Quentin Sep 7 '14 at 10:17
  • I am not sure now but I think that was never working and it is no bug. It says Daylight sensor and not light sensor... – Gerret Sep 7 '14 at 10:21
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    It detecting block light may have been the bug then. Even though it made way more sense. Anyway, here's a version actually using daylight. – Quentin Sep 7 '14 at 10:32

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