How to make a composter in Minecraft and get bone meal from trash

How to make a composter in Minecraft and get bone meal from trash

The composter is a vanilla Minecraft block that turns plant material and surplus food into bone meal. Instead of farming skeletons for bones, you toss in unwanted seeds, leaves and rotten vegetables — and get fertilizer to speed up crop growth. This guide shows how to craft a composter, which items give the most value, and how to automate the whole process. 

Preparation

What you'll need:

• 7 wooden slabs of any type (you can mix wood species in a single recipe)

• A crafting table

• Any trash to get started — seeds, leaves, vegetables from your farms

One log yields 4 planks → 6 slabs. Two logs give 12 slabs — a set for a composter with some to spare. 

Step 1. Crafting

Place the slabs in a U-shape on the crafting table: two at the ends of the top row, two at the ends of the middle row, three in the bottom row. The center and top-center stay empty.

The composter recipe on the crafting table — 7 oak slabs, the center cells empty

Step 2. How the composter works

Inside the block there are 8 compost levels (0–7). A filled level looks like a layer of podzol. When the 7th level is reached, after about 1 second the top texture changes to finished compost — that's the signal that you can collect the bone meal.

Key mechanic: the first item thrown into an empty composter always raises the level with a 100% chance. All subsequent levels depend on the type of material — each item has its own chance to add a layer. Because of this it's best to start with cheap trash (seeds, leaves) rather than a cake.

Step 3. Chance table — what to throw in

All compostable items are divided into 5 groups by their chance to add one level per use. The higher the chance — the less trash per bone meal.

Step 4. Smaller is more efficient 

Compression blocks give less compost than the individual items they're made of. Before throwing them in — break them down:

• hay bale (85%) → 9 wheat (65% each). 9 wheat give on average ~5.85 levels, while the bale gives 0.85. The difference is almost 7 times.

• Dried kelp block (50%) → 9 dried kelp (30% each). Just two kelp already have a 51% chance to add at least one level — that's more efficient than the block.

The exception is the cookie. One recipe from wheat and cocoa yields 8 at 85% each, while you can't turn them back into a block. Cookies are best left as they are.

Step 5. Automation with hoppers

The composter interacts with hoppers from two sides:

1. Hopper on top — pushes trash in automatically.

2. Hopper underneath — pulls the finished bone meal into a chest.

Basic layout: top chest → hopper down → composter → hopper down → bottom chest. You throw a stack of trash in from the top, and a minute later collect the bone meal from the bottom.

Automatic composter — top chest with wheat, hopper down, composter, hopper down, bottom chest 

Step 6. Comparator signal

If you place a redstone comparator behind the composter, it emits a signal of strength 0–7 depending on the fill level: 

• 0 — empty;

• 1–6 — fill layers (you can visually see the mass rising inside);

• 7 — bone meal ready to collect (a white texture appears on the surface).

This way you can make an automatic readiness indicator. For example, if you run a redstone line 7 blocks long from the comparator and place a redstone lamp at the end, it lights up exactly when the finished bone meal appears inside. 

Next to the composter stands a comparator, from which a redstone track runs to a lamp; the player throws in items, the mass inside grows, and at the 7th (final) layer the lamp lights up brightly, signaling that it's ready 

Common mistakes

• Expensive food in an empty block. The first layer is always 100% — better to start with seeds, not a pie.

• Expecting bone meal right after the 7th layer. The texture transitions to "ready" with a delay of about a second — click after the appearance changes, not immediately.

• Trying to dump in bamboo or poisonous potatoes. These items are permanently excluded from the compostable tag — they only work as fuel in a furnace (bamboo) or for nothing at all (the poisonous ones).

• Hopper from the side. A common fault in layouts. Only the top and bottom work.

Conclusion

The composter is a constant source of bone meal without farming skeletons — especially worthwhile for worlds with large automatic vegetable/seed farms, where the surplus of material goes unused anyway. It's suitable for survival, skyblock, peaceful survival mode and any scenarios where there's excess greenery.