How do you speed up composting? Turn it and add hydrated lime

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How do you speed up composting?

One of the things about making compost is that the words ‘composting’ and ‘speed’ don’t go together. I’ve been looking around to see if anyone has any ideas to add to my own because if there are ways of speeding up the process we need to know about them. So, How do you speed up composting?

Here we go through some of the main options. There are some relatively simple things you can do to bring about a quicker compost but whatever you do, you will always need to have patients to allow nature to take its course.

Can you make compost in 14 days?

If we are talking ‘compost’ that is black and crumbly with absolutely nothing of the original green waste in it that’s recognizable, then I’m going to say no, you can’t make compost in 14 days. It is possible to gather together some kitchen or garden waste, turn it over a few times and it will start the process of converting into compost. We have a post that goes into more details. See ‘Composting’, to see how to make the type of finished, quality compost that you need.

There will be evidence of the warming that takes place in the early stages of composting especially if you turn over a large amount. This will only happen if you have a large amount of material turn up all at once. If you are making compost from a large heap of green waste, then you will probably see steam rising from the heap.

When you mow the lawn there will be a heap of grass clippings which will generate clouds of steam if you dig it over the day after mowing. This will be from the heat that’s generated from the highly effective microorganisms that will quickly multiply within the heap.

How do you speed up composting? Add lime and turn it over.

The heating will sterilize many of the harmful factors that reside in organic waste. It will also destroy weed seeds although it can’t be relied upon as a ‘kill all’. There will always be be some survivors in the peripheries.

This stage will end after a day or two and the whole mass will cool down. The next and subsequent stages will be a follow-on of microorganisms digesting and breaking down the material further. This is what takes the time.

Heating can only happen if enough waste can be gathered together as one, large-enough, batch of fresh organic material. The problem with kitchen waste is that it arrives at the composter in small amounts. There isn’t enough to get any effective heat to happen. Some heating may occur but it won’t be much more than warming which will do little or nothing to sterilize the main part of the batch.

There are things you can do and add to accelerate the process. There are accelerators and hydrated lime will make a difference. You have to accept that it will take at least 3 months of regular turning to reach anything that looks like the black crumbly compost that’s needed.

If you try to use ‘compost’ that’s been in the making for just two weeks there may be hygiene issues. Because there hasn’t been a complete rot -down of all the components in the heap as a mass, there will be bits and parts that are still raw. These will carry potentially harmful pathogens which are best left non handled.

Waste that’s fresh from the kitchen will be relatively safe to handle. Waste that is half rotten should be left well alone and if you attempt to make compost in 14 days you do run the risk of being exposed to things which can cause harm. The best way is to go for the long rot. Give it all the time it needs to reach a satisfactory conclusion. Accept that this could take from one to two years, depending on the system and general attention that you provide. Get it right and you will have a compost that isn’t just safe to handle but will serve you well as a plant food.

The importance of shredding

A perfect example of shredding is lawn clippings. Grass that has been finely chopped will convert into compost faster than any other organic material. This is because everything about chopped grass is right for making compost.

Chopped grass has the right balance of all the ingredients needed to make compost and because a large heap will appear all at once the heating process is guaranteed to happen.

Much of the success that comes with lawn clippings converting quickly into compost comes from the fact that it’s chopped. Fine particles have a much bigger surface area for microorganisms to work on, so they can be much more efficient in the breaking down process.

Creating the same conditions as we see when lawn clippings are rotting down is what we need to try and repeat, as far as we can, with all composting systems. With lawn clippings it’s easy because they are already chopped but we need to do the same for other waste, particularly woody prunings from the garden.

Hedge trimmings will eventually rot down if they are left in a heap but shredding this down into small pieces will ensure that they will rot much faster. By shredding this type of waste it will take up less space in a compost bin and, if there is a large enough amount of material, you will see the same heating effect as with grass clippings.

There is a range of shredders available that are made for the purpose of shredding small branches of hedges and general woody off-cuts from the garden. Shredders are easy to use and it’s very satisfying to see large hedge trimmings being chopped down and take up much less space.

Shredding is less necessary for kitchen waste. Most of what comes out of the kitchen will be small pieces but where there are long pieces of vegetable peelings or stalks, it will help the process considerably if you take a sharp knife and spend a moment cutting it up.

Get the mixture right

When making compost from lawn clippings, it’s easy. The mixture is right, the carbon and nitrate level is where it needs to be and green grass will have sufficient moisture to get the composting process started. There is nothing extra needed to turn chopped grass into compost it can go by itself, although I would be tempted to sprinkle a generous dose of either hydrated lime or ground limestone on the top of the heap.

Kitchen waste is different. This tends to have too much of one thing and not enough of another. This is where you have to look at what you have and understand what needs to be added to get the balance right. Kitchen waste usually has a surplus of nitrate-rich material, which, on its own will rot in to something eventually but to achieve a successful conversion into a quality compost you need to add another ingredient to balance the nitrate level.

Add carbon based materials to balance the nitrates.

Here we are talking about carbon. There are a number of sources of carbon which are all readily available to you. This includes any paper or cardboard. Packaging cardboard is ideal for this and so is news paper.

Shredded cardboard or paper can be added to any compost system. You need to add a significant amount to make a difference, the ratio of carbon based ingredients to nitrate based is understood to be 20 carbon to 1 nitrate.

The inclusion of this type of material will also have the effect of improving the structure of the compost mass, whether in a heap or in a bin. It will keep the over all mix more open allowing air to get in.

Is your compost wet enough?

Compost won’t become compost if it’s too dry. It will just sit there and stay as a dormant heap unless it’s outside where the rain can get at it. If you are making compost from mainly kitchen waste, then this won’t be a problem. Kitchen waste is usually wet. You will need to add shredded paper or cardboard to it to balance the nitrates and this will soak up most of the surplus liquid and make use of it.

The dryness problem will happen if you have a covered bin full of dry grass, dried dead leaves and nothing added that has enough moisture in it to encourage microorganisms to thrive.

Whatever is happening in your compost bin, you need to take an occasional look and see if there is evidence of lack of moisture. Dig into it with a stick or something, if it sounds crackly and looks dead then now would be a good time to get the watering can, with a rose on it, and saturate the entire contents with water.

An open based compost bin will allow any excess moisture to drain away, so there should be no worries about over watering. If it looks wet then it is wet and any moisture will make a difference when we are trying to get things to rot down.

Is there enough air in your compost

It’s very difficult to seal a compost bin such that no air can get in at all. Compost bins are not air-tight and it doesn’t take a massive amount of air to supply the microorganisms that feed on green waste. Compost will form in a bin when it’s just sitting there but it will take longer to happen.

To speed things up you must open up the heap or turn it over. To get extra air into the contents of a static compost bin you could use an aerator probe which you push down into the mass of compost and pull it up, twisting it as you pull it. Keep doing this throughout the whole amount, regularly, will allow ait to get into the mix.

Does using a tumbler speed up composting?

Using a tumbler style composter will definitely speed up the composting process. The very action of rolling over the barrel will open up the mass of material within it, even if it does just one half of a rotation. It’s much simpler to roll over a barrel rather than digging over a heap or digging out the contents of a static bin and loading it into another.

There is no doubt that a tumbler will speed things up. But you may need a second compost tumbler to start filling while the contents of the first are allowed time to rot down completely and reach a constant point where there is nothing left of the most recent additions to rot down. To get the best from a compost tumbler system, you need to operate in batches.

When a batch has completed forming into compost you you should be able to remove it all from the barrel and either use it straight away or store it in bags for later.

Why you must use hydrated lime

Some will tell you that adding lime to compost will hinder the microorganisms that are need to break down the green waste into compost.

Having made compost for many years I’ve always used hydrated lime and ground limestone and found that this definitely helps with the process.

It’s important to make sure that you use the correct hydrated lime or ground limestone and not quicklime. This is lime that has been burnt at high temperature, it is only of use to the building trade and must not be used when making compost as it will cause problems.

Hydrated or ground lime will lower the acidity in the forming compost which will encourage the microorganisms to work at their most efficient level. If the contents of a compost bin or tumbler are too acidic then there is a risk that it will be preserved rather than rot down.

Compost accelerators

There are compost accelerators available to buy that are available in a powder-form. This is a concentrated dried culture of bacteria on a medium which when moistened will multiply at a tremendous rate. When you add the powder to rotting green waste, it will speed up the process very quickly.

The down side to this is that it tends to produce lactic acid, among others, which has a tendency to preserve. If you leave it long enough and do nothing more to it then it will eventually rot down. If you are thinking of using any of these accelerators I suggest using a liberal amount of hydrated lime or ground limestone to reduce the acidity.

What are pathogens?

Pathogens are the germ agents that are harmful to animals ( and humans) if ingested. They are responsible for diseases and many illnesses that should be avoided. Whenever you handle any material that may contain these harmful agents you must wear rubber gloves. It’s also important to wash hands afterwards in a suitable disinfectant. Pathogens will be present in compost, particularly in the early stages of rotting down. When compost has been fully formed then the risk is very much reduced because the pathogens themselves will have been largely consumed by microorganisms and, if they are there, worms.

How do you speed up composting?

To sum up:

6 things that you need to do to speed up composting

  1. Focus on getting the right balance of ‘browns’ and ‘greens’.
  2. Shred anything large; small pieces speed up composting.
  3. Turn over the composting mass to introduce air.
  4. Add a sprinkling of white, hydrated lime to neutralize acids.
  5. Don’t allow the composting mass to become dry.
  6. A large heap will heat up more than a small heap but heat isn’t always necessary.

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 What not to put in your compost pile How long does it take to make compost? What can you put in your compost bin?

What is a compost accelerator? Can you put grass clippings in compost? Can I put urine in my compost bin?

Smelly Compost How do leaves decompose faster? Do worms help compost? 

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