Stone generator bone meal farm

A self sustaining bone meal farm that runs on moss. A stone generator built from two lava buckets, a water source and six pistons feeds fresh stone into a small pit, a dispenser bone meals the moss block in the middle, and the moss spreads over that stone and grows moss carpet, grass and azalea on top. Water pushes those plant drops into two composters sitting on hoppers, the composters turn them back into bone meal, and a dropper pair refills the dispenser before the surplus goes to the double chest. It only needs a few stacks of bone meal to prime it and then it feeds itself. A lever and a redstone torch switch the whole thing off.

The chest stays empty at first because the dispenser and the two droppers fill to capacity before any bone meal is routed to storage, so give it several minutes.
Set the repeater at 1:22 to 2 ticks, kinzideffufer9083 needed 3 ticks instead on 1.21.8.
If the generator makes cobblestone instead of stone, add one more repeater and put the repeater line on full delay, the water is reaching the lava while the pistons are open.
Face east or west when you dig the first hole and place the observer exactly as shown, wrong facing is the most common reason it never starts.
Java only. On Bedrock water runs straight through the trapdoors, so replace them with dispensers holding the water buckets.
If it stalls after running for a while, bone meal the centre moss block by hand once and the cycle picks up again.