If you think there’s only one or two types of composting, you might be in for a surprise.
There’s actually dozens of ways to turn garbage into black gold, and as people get inventive, more of being thought of.
Each compost method has its pros and cons – and its fans and detractors. In reality, most methods involve playoffs. For example, the Berkely method is seriously fast – but requires a serious amount of work. A simple static compost pile is less work – but takes a lot more time.
In this guide to the different types of composting, we’ll start by looking at hot v. cool composting. Then we’ll look at the factors to take into consideration when choosing a composting method. Finally, we’ll then review some of the methods available so you can choose which is best for you.
- Factors to consider
- Hot v. cool composting
- The Indore Method
- Berkeley method
- Insulated hot bins
- Static piles
- Compost tumblers
- Pit and trench composting
- Shifting compost pile
- African keyhole gardens
- Sheet, Blanket or Lasagna Composting
- Windrow Composting
- Related Technologies
- Bokashi Bin Composting
- Vermiculture (worm composting)
Factors to consider when choosing a compost method
Do you need compost fast or slow?
You are most likely to need compost quickly when you start a new garden. Over time, with planning, you should be able to allow compost to mature more slowly.
Do you have a lot of space or a little bit of space?
Some composting methods require a lot of space – others require very little. For example, if you have no or little garden, you might choose to have a worm bin in your kitchen. If you have a large garden, you might choose to have a series of compost piles in a multi-bin system.
Your climate (and pests)
A hot dry climate can drain moisture from above ground compost heap – it might be worth considering pit or trench composting. On the other hand, a wet climate with plenty of slugs is not good for methods like sheet composting.
How much energy – and time – do you have?
If you’re young, energetic and have lots of time, you might want to consider the Berkely method. If you’re not, then you might want to consider a method which does not involve a lot of turning, or a tool like a compost tumbler which make turning easier.
How much material do you have to compost?
If you have a lot of material to compost, you should consider hot composting, as it rapidly deals with large quantities.
Dig or no dig?
Some gardeners (myself included) prefer a no-dig method of gardening, which avoids disturbing the complex interplay of microorganisms and microconidia in the ground. That rules out methods such as pit or trench composting.
Hot v. Cool Composting
The main advantage of hot composting is that it can produce large amounts of compost in a shorter time. It can also kill most weed seeds and pathogens in a short period of time.
It’s an excellent choice for an energetic gardener who needs to quickly build fertility for a large garden.
However, some methods of hot composting involve a lot of work. If you’re less energetic, the regular turning of compost may well put you off. You also need to pay more careful attention to the moisture level and temperature of your compost pile.
Cool composting has its own advantages. It requires far less work, and most cool systems allow you to add a little bit of compost at a time. Less nitrogen may be lost (depending on the method and weather), and some research suggests that the finished compost has an increased ability to suppress plant diseases. This may be because hot composting, while killing pathogens, also kills the biocontrols which attack plant diseases.
On the other hand, exposure to weather can lead to loss of nutrients. It can also take much longer than hot composting – sometimes up to 2 years. In contrast to hot composting, it won’t kill weed seeds. (Some sources argue it won’t kill pathogens either, but in fact worms may do at least some of that job.) You’re also more likely to have more browns which haven’t fully decomposed.
The Indore Method
The Indore Method was developed by Sir Albert Howard in India in the first half of the 19th century. The Indoore method originally consists of alternating layers of animal manures, along with materials such as leaves, brush or straw and chalk or earth on a base of brush.
The material would either be made into a compost pile around 5 feet high or buried in a pit 2-3 feet deep. The pile would be turned twice. When flies were a problem, the pile would be turned again or covered with a layer of compacted soil. While the Indore method does involve hot aerobic (with air) composting, it may also involve cool, anaerobic (without air) composting.
Later forms of the Indore method also included human waste.
The Indore method was well suited to the time and location. For instance, his method involved leaving tough materials out to be broken up by passing carts. The essentials of the Indore Method – with modifications – continue to be widely used in parts of Asia. But for most garden composters, there are easier ways to accomplish good compost. Most of us, for example, don’t want to dig a pit every time we need to make compost!
Some of the advice is also outdated. For example, we now know that we don’t need to add lime or soil in order to make compost.
Developed at the University of California in the 1950’s, the Berkeley method is probably one of the most famous hot composting methods.
It was designed to maximise heat and speed, with compost being produced in 14-21 days, and is similar to methods used by some commercial composters.
The requirements are fairly onerous, though!
- Compost materials need to be shredded so that the size is between 1/2 to 1-1/2 inches. Woody materials should be put through a shredder.
- The compost heap should have a carbon:nitrogen ratio of 30:1.
- Moisture needs to be maintained at about 50%.
- The height, width and length of the compost heap should each be a minimum of 36 inches (3 feet) to avoid heat loss.
- The pile is built in one go, with nothing added afterwards.
- The pile must be turned regularly to avoid overheating, with the outside of the pile being turned into the inside.
For more information see the University of California’s guide to the Berkeley method.
Even if using this method, the compost heap will benefit from being left to mature – and the attention of worms – after the process is finished.
Insulated hot bins
Insulated bins such as the HotBin (HotBin review here) and the Green Johanna make use of insulating materials to increase the heat and speed of composting without the need for turning. They are designed to encourage air flow, but you’ll also need to add material to create airspaces inside the composting.
These can’t deal with the same quantities as the Berkeley methods, and take a bit longer to finish composting. They can, however, achieve temperatures hot enough to kill pathogens and weed seeds.They also allow for compost to be added in batches, rather than having to be added in one go.
Some compost piles are simply constructed and then left till ready. These are often an example of cool compost, and can take up to two years to be ready. However, it doesn’t always have to be this way!
Joseph Jenkins, author of the Humanure handbook, is a big critic of turning methods. He achieves hot compost by doing the following:
- Ensuring the compost is contained on each side, for example with wire or wood.
- Incorporating materials such as weeds and straw in order to trap air in the compost.
- Putting a thick level of cover material, such as straw or manure, under, around and over the pile.
- When adding material, simply dig a hole, tip the material in, and cover it back up again.
Other composters turn their pile once or twice. Charles Dowding, for examples, turns his compost once to aerate it and also to check to see how dry the interior is inside. A dry compost heap will benefit from the addition of moisture.
The Berkely method takes a huge amount of work, while cold composting can take a long time. Compost tumblers aim to solve this problem by making the effort – specifically the turning – a lot easier. They are usually in the form of a barrel mounted on a stand, with a handle to turn them. Some forms are also designed to be rolled along the grass.
Compost tumblers take a little longer than compost which is turned once a week. A Which Magazine report found:
- A compost bin, forked over weekly, took ten weeks to produce compost.
- A compost tumbler took fourteen weeks to produce compost.
- A compost bin that wasn’t forked over took four months longer than a compost tumbler.
Most people don’t want to fork over a compost bin every week, so compost tumblers are still a valid option for people who want something easier. Compost bins can handle smaller amounts of compost and are much quicker than cold composting. However, the Which report did find that compost tumblers became harder to turn as the composting process continued.
Pit and trench composting
This is one of the simplest methods of composting. In the UK trench composting is a popular way to prepare the ground for next year’s runner beans. Pit composting is also suitable for people who live in areas where (above ground) composting is restricted.
You simply dig a hole or trench, throw in your compost material, and cover it up again. The soil covers the odours, and soil bacteria will turn your food scraps into nutrients for plants. You can then plant on top of the site the next year.
The main thing to be aware of is the need to dig a hole deep enough that the materials will not attract predators. If you are adding 6 inches of food, consider making the hole at least 12 inches deep, and covering with 6 inches of food.
Pit composting is particularly useful in dry countries where water loss is a problem. Inckel et al, in The Preparation and Use of Compost, describe a process where three pits are dug. The compost is then turned from one pit into another. In this process, the pit is not necessarily covered over. Water loss can be further prevented with the addition of clay at the bottom of the pit.
There are some drawbacks to the method. Digging disturbs the soil, damaging the network of Mycorrhizal fungi that carry huge benefits for plants. In covered pits and trenches, it may also lead to anaerobic composting, which releases methane rather than oxygen into the air. It is also more difficult to follow the progress of the compost than with dry compost.
Variation: Deep Trench Method
A variation of trench composting is the deep trench method. This involves a deeper trench of up to 2 feet deep. You add food scraps and leaves and then cover with an inch of soil. Repeat until the trench has risen to within 6 inches of the top. Finally you fill the trench with soil. This method may require extra protection against pests.
Movable compost pile
The compost heap has immense benefit for the ground under and around it. Nutrients leach out of the compost pile, improving the soil. The shifting compost pile technique aims to take advantage of this, leaving rich ground in its wake as it moves round the garden.
To put in place, simply build a compost pile in part of your garden. This can be on bare earth, or on top of weeds you want to smother. After a few weeks, turn the compost, exposing the enriched soil. When the compost is finished, it can simply be spread around instead of needing to be wheelbarrowed to the vegetable garden.
The Rodale Book of Composting describes a variation on this used for raised beds. The soil is removed from one side of the raised garden. A temporary structure is built with breeze blocks and the compost built until it reaches four feet high. When the compost is finished, the compost is removed to enrich the raised bed and the structure is moved along the raised bed.
African keyhole gardens
African keyhole gardens were developed in Lesotho, Africa for intensive vegetable production. They are a neat way to embed composting into a raised bed.
The beds are often constructed from leftover materials such as stones or bricks, which help retain heat at night time. They are usually constructed in a circle, with a section cut out (the keyhole) which gives you access to the center. In the center a compost bin is placed. The bin can be made from wire or interwoven sticks.
These keyhole gardens have two big benefits.
- They minimise work, as you don’t need to transport the compost around the garden.
- They allow you to benefit from nutrient run-off from the compost.
Hügelkultur (pronounced hoo-gul-culture) uses rotten wood as the basis for a no-dig raised bed, with a mound of rotting compost on top.
The raised beds are usually in the form of mounds. While there are variations on how the mounds are constructed, a typical format might be as follows:
- Place large logs at the bottom of a mound.
- Cover with branches, sticks, brush and twigs.
- Add grass, newspaper, cardboard e.t.c. depending on what you have available.
- Put a layer of manure or compost on.
- Finally, add a layer of soil.
They are a lot of work to build, but have some serious benefits.
- As wood breaks down over a very long time, the system can carry on producing nutrients for 20 years or more after it has been created.
- Hugelkultur can also generate internal heat which keeps plants warm.
- The system retains moisture, helping plants to weather droughts.
- As the wood breaks down, it creates air pockets, aerating the soil.
You can read more about hügelkultur on Permaculture.co.uk.
Sheet, Blanket or Lasagna Composting
Sheet composting (which I’ve also heard called lasagna composting) requires minimal work. The method both enriches the soil and smothers weeds, but is not suitable for every climate.
You may wish to start with a layer of compost to further suppress weeds. Then simply spread compost materials such as grass or leaves (or, ideally, both).
A variation of sheet composting was popularised by Ruth Stout in the 1950s. Ruth used a thick layer of straw to cover the ground. The straw smothered the weeds, and when new weeds appeared she simply covered them with more straw. The straw is pulled back for planting.
There are several advantages. Turning compost piles, hoeing and weeding are virtually eliminated. You can see Ruth describing her gardening method in the video below.
However, my experiments in wetter climates have thrown up a few problems. Grass rapidly becomes a wet mess which prevents oxygen from getting to the soil. Slugs and snails also find the grass a welcome refuge. The system does work with seaweed, which slugs hate.
Windrow composting consists of elongated piles of compost. These can be any length, although the height and width needs to be more carefully considered.
Windrow composting is usually used for large scale and commercial composting. Windrows may be turned to aerate them, or left static, although Leslie Cooperband, in the Science and Art of Composting, say these often go anaerobic in the centre. Windrows may also use a system of pipes to allow oxygen to circulate through the compost, a process known as ‘passive aeration’.
There are other forms of breaking down organic material. Some of these do not produce finished compost while others produce a valuable soil amendment. While often called composting, both the process and the result can be quite different.
Bokashi Bin Composting
Bokashi bins use essential mico-organisms (EM) to break down food scraps. The EM are held in a bran, which is added to food scraps. The food is pressed down to expel oxygen and the box sealed to allow anaerobic (without air) fermenting to take place.
The name Bokashi Bin Composting is actually a misnomer. The system produces pre-compost, not compost. This pre-compost can then be added to a compost heap or dug into the ground. Liquid is also produced through the system, which some advocates dilute and use as a compost tea.
Vermiculture (worm composting)
Vermicomposting uses worms to turn food scraps into worm castings. Vermicomposting systems also tend to use a specific type of the worm such as the red wriggler (Eisena Fetida).
Vermiculture is also known as vermicomposting. However, there is some debate over the names. In his book The Humanure Handbook Joseph Jenkins argues that because food scraps are digested by the worm, and produce worm castings, the process shouldn’t be called composting at all.
However, it’s worth noting that bacteria are likely to assist in the breakdown of organic material. And, as we explored in The Science of Compost, worms also play a major role in traditional composting practices.
Worms are happy living in a shallow container, and reproduce quickly. They also eat a lot! (Estimates vary from half their own body weight a day to their own body weight a day.) That means a small bin can usually deal with the food of a family of four without a problem.
This makes the system excellent for the composter with limited space. It is commonly used in the kitchen and, if properly maintained, does not cause problems with odours.
As for drawbacks, the obvious one is that not everyone can tolerate worms, whether in their house or not. Most worm bins are smallish, so they are not suitable for dealing with large amounts of waste.
There’s no one right or wrong way of making compost (although many would disagree!) I hope that you, like me, have fun experimenting with different methods until you find the one that works best for you.