Composter

A composter is a block that converts food and plant material into bone meal. It also serves as a farmer villager's job site block.

Natural generation
Composters generate in farms in all village types.

Usage
Composters can be used to recycle food and plant items (excluding bamboo, poisonous potatoes, dead bushes, nether wart, meat, and fish) into bone meal. To do so, the player must any of a selection of items on the composter. When an adjacent comparator is facing away from the composter, a comparator signal strength of up to 8 is emitted depending on the fullness of the block.

Composters appear to have an empty interior. As such, entities can enter and exit a composter through the top, but not the sides or bottom. The composter has a “floor”, whose height depends on the fullness. When the composter is completely empty, this floor is slightly above the block below, and when it is completely full, there is a slight dip on top. When the composter’s fullness increases, any entities inside will be pushed up accordingly‌.

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. The table below lists supported items, which have different levels of compost-ability. The higher the percentage of an item, the more likely it is for it to add another layer of compost. Each layer of compost has a podzol-like appearance. When the composter reaches the 7th layer of compost, the compost changes appearance indicating that bone meal can be collected by the composter a final time.

The following table shows the items that can be used in a composter, the percent chance for an item to add a level of compost, and the average number of items needed to fill a composter:

Hoppers
Composters can interact with hoppers. A hopper directly below a composter will pull bone meal from it. A hopper directly above a composter will push items into it. See for more details.

Hoppers cannot interact with the sides of a composter.

Changing villager profession
If a village has a composter that has not been claimed by a villager, any resident villager who has not already chosen a job site block has a chance to change their profession to farmer.

Redstone component
A composter can act as a power source for a redstone comparator. With a composter behind it (either directly, or separated by an unpowered solid block), a comparator outputs a signal strength between 0 and 8, proportional to how full the composter is: 0 for empty, 1 for $1/7$ full, 2 for $2/7$ full, 3 for $3/7$ full, 4 for $4/7$ full, 5 for $5/7$ full, 6 for $6/7$ full, 7 for completely full but the bone meal is not ready to collect, and 8 for completely full and the bone meal is ready to collect. However, if there is a block between the composter and comparator, the comparator does not immediately update.

Fuel
A composter can be used as fuel in a furnace to smelt 1.5 items.

Trivia

 * Using individual wheat items to fill a composter is much more efficient than using hay bales. The chance of getting the composter's level increased by at least one using 9 wheat items is ~99.92%, and the number of levels increased can be anywhere from 1 to 9. Using a hay bale, there are only two possibilities: increase composter's level by 1 (85%) or nothing happens (15%).
 * The compost texture is part of the podzol texture.

Gallery
Kompostér Komposter Composteur コンポスター 퇴비통 Kompostownik Composteira Компостер ถังหมักปุ๋ย 堆肥桶