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  • Le cercle des Créatures Terriennes

Feeding the compost box

Making your compost in an apartment is like following a recipe. With experience, we will be able to move away from it.

It is necessary to take care of the compost regularly (it is a small farm), limit as much as possible the waste sources of olfactory nuisances (meat, fish, dairy products, ...), vary the inputs and find for the compost box a place sheltered from the cold and the rain.

Some principles of "dietetics"

Carbon and nitrogen ratio

The compost box can be compared to a microscopic farm, microorganisms are raised there. They are the ones who break down the waste and provide the humus, the future food of the plants. Microorganisms need nitrogen, which is a source of protein and carbon, which is a source of carbohydrate-based food.

· Our "green" waste (peelings of fruits and vegetables) are materials rich in nitrogen that is to say, they have a very low carbon / nitrogen ratio.

· Brown matter, which is the dry parts of plants, has a high carbon / nitrogen ratio.

For example: coconut fiber or "coco peat", corn fiber, hemp fiber, wood crushed into a thousand pieces, dry plant debris, fallen leaves, egg boxes and unprinted paper in pieces, cardboard confetti, pruning wood, straw, etc.)

The carbon/nitrogen ratio refers to the carbon and nitrogen content of a material.

Kitchen waste: 15/1

Sheets: 40/1

Straw: 80/1

Paper: 170/1

Fresh sawdust: 500/1

The ideal ratio to make a good compost is from 25/1 to 30/1. This means that by weight, the ideal ratio is from 25 to 30 for carbon to 1 for nitrogen knowing that green waste, very wet, is much heavier than brown matter.

When you start the compost box, there is too much carbon (brown, hard waste) and microorganisms run out of energy, slowing down composting.

But if there is too much nitrogen in the compost (green waste) the bacteria do not have enough carbon to digest it, then part of it will be lost by volatilization of ammonia (and the compost will smell bad!) if there is still room in the compost box, then it is possible to add brown waste.

Humidity conditions

Kitchen waste is too wet to be composted on its own. Their humidity is on average 85% while in the ideal compost the humidity does not exceed 65%.

The bio-waste inputs must therefore be balanced with dry matter, initially consisting of the fibrous envelope of the coconut. This allows the smooth running of the process by structuring the compost, providing carbon and absorbing moisture.

It can also be wood crush, which has the same properties, although it is less absorbent. Sawdust (from untreated wood) mixed with other brown materials can also be used. Thus, peelings can also be mixed with straw, fallen leaves, paper, cardboard ...

Keeping a little ash or charcoal available near the compost box, in addition to that of the initial mixture, is useful. Indeed, charcoal has countless pores giving it absorbing properties.

Neutral environment

Microorganisms prefer an environment with a neutral ph, to slightly acidic. As a result, the intake of acidic foods should be moderated, especially at startup.

Some vegetables (spinach, tomatoes, cauliflowers, artichoke, onion, mushrooms) and condiments are acidic foods. We avoid feeding the compost with peelings of fruits and vegetables that are cooked with condiments. Among the acidic fruits, we find especially citrus fruits, fruits that are not ripe (the less ripe they are, the more acidic they are), all fruits with an acidic taste, such as pineapple, kiwi, passion fruit, all small red fruits (strawberries, raspberries, blackberries, etc.), some varieties of apples such as Granny Smith , cherries, apricots and plums. Cereal grains such as amaranth, wheat, spelt, kamut, corn, barley, quinoa, rice, buckwheat and rye are acidic. Vegetable proteins such as peanuts, avelines (hazelnuts), beans, legumes, lentils, cashew nuts, walnuts, Brazil nuts, chickpeas and green peas are also acidic.

Compost can be fed from cooked plants without the addition of acidifying foods.

Acidic foods are not to be avoided but to be known in order to be balanced with other less acidic foods. For example, it is preferable to avoid a high proportion of citrus fruits and cauliflower in the same intake because of their bactericidal effect which would lead to a (temporary) decrease in the population of bacteria and therefore a slowdown in composting. It would be better to reserve some of this waste in the bio seal for the next time or to use it differently.

The level of the acid ph of the coffee grounds depends on its composition but also on how we made our coffee. Using a coffee maker with hot water will remove much of the acidity and the ph is then close to neutrality.

Sawdust reduces acidity.

Example of feeding a compost box for 189 days:

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