There are lots of benefits to a compost heap. For example, you can easily get rid of your kitchen and garden waste, and the soil around your garden will be more nutritious when you add soil from the compost.
It’s hard to think of reasons not to have a compost heap if you have a garden. There are certainly plenty of good reasons, as we detail below. It doesn’t take much more than a bit of knowledge, a good supply of garden waste and a bit of patience – and you’re good to go.
Facts and Composting Methods
Compost is decomposed organic matter. You can make compost from your garden waste, for example, which can consist of shredded branches, leaves and perennial tops, and from green kitchen waste.
Garden waste is turned into compost by a microbiological process in which micro-organisms such as fungi break down the dead organic matter. The organic material we put on the compost heap, such as leaves and branch debris, is called windrows.
Completely decomposed compost is a dark brown residue, relatively rich in potassium and phosphorus, but relatively poor in nitrogen. When the compost comes into contact with the soil, it becomes what we call humus.
The main advantage of keeping as much garden waste as possible on your own land is that you can make a good, nutrient-rich compost that you can spread on your garden soil to improve the soil.
In particular, soil structure and micro-life will improve if you improve the soil with compost.
There are 2 ways to compost: cold composting and hot composting.
Anaerobic (without oxygen): decomposition, often called fermentation or putrefaction. It is usually accompanied by the release of methane or a foul odour of hydrogen sulphide (the smell of rotten eggs). Anaerobic digestion is slow and generates little heat.
Aerobic (with oxygen): a naturally occurring process in nature where organic waste is converted into humus. There is little or no odour. The process generates a lot of energy in the form of heat. The heat is beneficial as it kills pathogens and parasites.
The casters that help with composting are: bacteria, fungi, millipedes, earthworms and other living organisms.
There are three types of bacteria:
- Psychrophiles (bacteria at low temperature)
- Mesophiles (5-40 °C) that do most of the work in the compost heaps
- Termofile (40-95 °C)
All bacteria need nitrogen and carbon to survive and thrive. Nitrogen gives microbes the raw element they need to multiply. Carbon is the source of energy. Bacteria have a complete meal when the ratio of carbon to nitrogen is 30:1.
A water content of 40-60% is ideal for bacteria. If it is less than 40%, the bacteria will slow down and go into hibernation. If the water content is above 60%, the pile is too wet. This means that it loses too much air and anaerobic conditions occur.
When the pile is turned over, the microbes get fresh air and rapidly increase in number. More microbes = faster decomposition = faster compost.
As the pile cools or in the later stages of decomposition, other larger organisms settle.
- Fungi are important decomposers in the compost heap, but not as effective as bacteria.
- Nematodes or roundworms
- Hunting spiders
- Bench Biter
- Running beetles
A little detour. A clever detail for grass clippings:
Grass clippings can be recycled directly by leaving them on the lawn when you cut them. The clippings are 90% water and break down quickly, releasing nutrients equivalent to one or two fertilizer applications a year.
How Do You Make Compost?
In nature, dead plant parts decompose where they fall to the ground.
In the garden, you can also leave dead plant parts in the beds to decompose there. You can also cut small branches and stems into smaller pieces. Hedge clippings can also be cut into small pieces and pushed under the hedge.
The mulch will retain moisture in the soil and eventually break down into compost, which improves the soil.
If you want a neat and tidy garden, you can collect garden waste in a compost heap or compost bin. You can also compost your green kitchen waste here. This will increase the nutrient content of the finished compost.
At the same time, it allows you to use the compost in exactly the places in the garden where soil improvement is most needed.
How to Cold Compost:
- Put a layer of smaller branches and twigs at the bottom of the compost bin.
- Mix garden and kitchen waste well and put it on top.
- You can keep adding new green waste until the bin is full. Remember to mix the different types of waste.
- Water the pile well.
- If necessary, cover the pile with a tarpaulin to retain moisture and prevent the nutrients from being washed out when it rains. Remember to water the heap if it is covered.
- Decomposition is faster if you occasionally shuffle the compost, i.e. mix the material or move it to a new pile.
- After 1-2 years, the compost is completely transformed. You can also use the partially transformed compost for soil cover.
How to Hot Compost:
Hot composting requires large amounts of garden and kitchen waste and a little more effort, but has more advantages than cold composting:
- Disease germs, pests and weeds are killed as the compost material gets about 60 degrees hot during decomposition. Turnover is faster.
- After only 2-3 months you will have half the compost. After ½-1 year it is fully converted.
You need a large pile of garden waste, at least 1 cubic metre and preferably more, to be able to hot compost. This is necessary to allow the temperature inside the heap to rise sufficiently during decomposition.
The pile should be covered with a tarpaulin, an old blanket, a thick layer of straw or similar to keep the heat in.
If you want to be sure of killing disease germs and weeds, the heap should be staked after a few weeks, when the temperature inside the heap starts to drop. This means that you move the compost material around with a handle, so that the outer material goes inside and vice versa.
If you choose hot composting, you cannot use compost worms, which thrive best at a temperature of around 25 degrees. Compost worms will die if the temperature gets below freezing or above 28 degrees.
Advantages of Composting
- Improves soil conditions and structure
- Improves soil’s ability to hold water
- Promotes living organisms
- Helps dissolve mineral forms of nutrients
- Protects soil from chemical imbalance
- May control certain pests biologically
- Helps return organic matter to the soil and keeps it out of landfills and waterways
Here are some simple composting terms:
- Composting: controlled decomposition of organic matter
- Compost: Partially decomposed organic material
- Humus: Completely decomposed organic material
- Mulch: Organic or inorganic layer on the soil surface
- Brown material or carbon part of the composting process: leaves, sawdust and wood chips
- Green materials or the nitrogen component of the composting process: manure, food waste, wilted flowers, nitrogen fertilisers and grass clippings
The ideal ratio of brown to green material in composting is 30:1 (30 brown: 1 green)
What Can Be Composted?
The material that can be composted depends on the composting method you use. It is of course possible to compost many more things industrially where machinery, technology, labour and time are available in abundance, including dog waste, meat and dairy products. These three items are not usually recommended for home composting.
This is a sample of the items that are suitable for home composting.
- Leftover fruit and vegetables (stems, seeds, peel and skin)
- Bread, groats, rice, flour, cereals and pasta
- Plant residues, wood chips, plants, flowers, leaves, straw and hay
- Natural fibres (cotton, wool and flax)
- Hair (from humans and animals)
- Manure from herbivores
- Coffee grounds and filters and tea leaves and bags (without staples)
- Newsprint, paper, cardboard, paper plates, paper cups and napkins
What Should You Not Put in the Compost Heap?
- Weeds should not go into the compost heap. This applies mainly to weeds containing seeds, as well as weeds in flowers and roots of perennial weeds such as ragweed. Throwing weeds in the compost can increase the risk of spreading weeds where the finished compost is spread. Some plants that are in flower can develop seeds even if they are pulled out of the ground. An example of this is dandelions.
- No sick plants in the compost. This could be planted with eyespot, powdery mildew or similar. It can also be plants attacked by pests. Sick plants, like weeds, can pass on their diseases through the finished compost.
- Prickly plants. This is especially true for roses, thistles, hawthorn, and barberry, as they can be unpleasant to handle.
- Certain types of food waste. This can be meat and leftovers from prepared food. In general, no animal products belong in the compost heap. They smell and can attract pests such as rats and foxes. Another organic waste such as vegetables (even cooked), coffee grounds with filters, potato peelings, etc. is fine.
- Excrements from cats and dogs. These can contain parasites that infect humans.
- Banana and citrus peel. If these are not organic, the peels may contain pesticides that can inhibit the decomposition of the compost.
- Ash from the stove does not belong in the compost heap unless you are absolutely sure that you have used clean wood, otherwise, it may contain toxic heavy metals.
- Pressure-treated wood and newspapers and magazines with printing ink. These may contain toxic substances.
- Vacuum cleaner bags, milk cartons, and cigarette butts. These items are domestic waste and belong in the bin, where they can be incinerated.
Types of Compost Bins
Compost bins can be classified in many ways, but the two most popular are “storage bins” and “turning bins”. Storage bins include bins constructed from wire, wood, masonry, plastic or a combination of these materials. Reversing bins usually include barrels that are turned horizontally or end to end.
When setting up a holding or turning bucket, make sure it is in an area protected from dry wind and within reach of a garden hose. It is also a good idea to place the unit/container in a shaded area and not in direct sunlight.
Storage bins are the most popular form of home composting system. It is the simplest and cheapest form of container, but it is slower to produce compost. Depending on maintenance, it can take six months to two years to produce finished compost.
Whether you use wire, wood or plastic, the compost bin should be at least one metre wide, one metre long and one metre high. Larger bins work even better because of better thermal insulation.
It is a great advantage to build two or three units/segments. These types of containers facilitate turning and maturing of the composting material. You start at one end of the bin by adding a mixture of brown and green material (30:1). When the first pile breaks down, you move it down to the second section and start again in the first section. When the second part decomposes further, move it to the third part for final storage. When the third part is finished composting and the compost has been collected, move the second part to the third, the first to the second and start over with the first. You will always have compost in the different stages of decomposition.
Whether you use the sectioned bin or a single bin with a single section, the sandwich method is the best way to build a compost heap.
- Alternating layers of green and brown material
- Water each layer until damp (not wet) before adding an extra layer on top
- Continue layering until the pile is about a meter high, ending with a layer of brown material (smaller particles break down faster, so try to cut larger plant parts and food scraps into smaller pieces)
Turning bins produce compost faster than a storage bin if they are regularly maintained. They can produce compost in two months or less. Barrels often have less capacity than most other containers, including storage containers, making them more suitable for people with smaller amounts of plant residues and food scraps. Turning bins are good for keeping pests out. Organic waste should not be added continuously, but stored until the first batch has been processed. Of course, storage of organic waste can be problematic in itself.
The most common turning containers are plastic barrels. Compost bins can be turned either horizontally or vertically depending on the model or how you construct it.
How to Use Semi-Transformed Compost
Semi-turned compost is coarser, smells slightly sour and still contains residues of not fully turned plant parts.
You can spread half-rotted compost on top of the soil in the beds. Here, the compost will gradually digest completely and the nutrients will be released at the same time for the plants to absorb. Semi-rotted compost also improves soil structure and retains moisture in the soil.
You can put half-rotted compost in the beds in autumn. There is little risk of nutrients leaching out over the winter. The nutrients are bound in the compost and will only be released when temperatures rise in spring and decomposition starts again.