Composter

Composters are found on village farms. They can be broken quickly with an ax, but once broken, they won't retain their compost. You can also craft a composter yourself by using wood slabs. You will need seven wood slabs of any wood type in a U shape in the crafting grid.

A naturally spawned composter in a farm (via screenshot)

Composters are used to recycle food and plant-based (excluding bamboo, poisonous potatoes, dead bushes, meat, and fish) items into bone meal. Composts have an empty interior which fills up as you add organic matter to it. After the composter is completely full, it will drop one bone meal and become empty again.

Composting

The composter can be filled with compost, which is done by adding compostable items to it. When successfully adding an item, a green particle appears. Every layer of compost looks similar to podzol. When the composter reaches the 7th layer of compost, its appearance will change, this indicates that the bone meal is ready to be collected by using the composter one final time.

Green particles appearing after composting (via screenshot)

Villager Jobs

If there is a composter that has not been claimed by a villager, any resident villager without a job site can interact with it and change their profession to a farmer.

The composter is very useful for repurposing extra or unwanted organic items such as cactus, kelp, etc. It is a great source of bone meal. Since it is made of wood, you can use it to fuel furnaces, but it is not very efficient.

Q. What item fills up the composter quickly?

A. The items that will fill up the composter quickly are cake and pumpkin pie.

Q. Can you compost eggs?

A. Yes, you can compost eggs as they are spam food.

Q. What is the most common item used for composting?

A. Baked potatoes are used the most for composting, as potatoes are easy to farm and you can end up with more than you need.