This article should be read alongside “How Composting Works,” which gives details about how to compost successfully. In short, all composting involves a proper balance of nitrogen-rich materials (food scraps, grass clippings…) with carbon-rich materials (leaves, straw…). These materials need to be in an aerated environment, where they are then decomposed by microorganisms.
Nature has no “compost bin”: nature seamlessly decomposes matter wherever it falls, and reintegrates it with the soil. Rather than removing and segregating the composting process, we can imitate nature by practicing direct composting in our growing spaces. Not only is this simple, but it also ensures that the microorganisms and earthworms in our vegetable beds are nourished and active year-round, leading to a healthier soil. People who practice direct composting may also want a small separate compost bin in order to create compost for seedlings and transplants.
Surface composting with mulch:
In surface composting, all of the annual plants are cut down and left in the vegetable bed at the end of the season. The roots decompose directly in the soil, and the rest of the plant decomposes on the surface. All of the nutrients contained within the roots, stems and leaves remain within the bed, providing long-term nourishment for the soil organisms.
End-of-season garden plants already tend to have a relatively balanced carbon-nitrogen ratio, though may be a bit high in nitrogen. For this reason, and also for aesthetics and for the general benefits of mulching, surface composting is paired with mulching techniques. The beds are constantly covered with a layer of mulch, like leaves. In the autumn, plants can simply be cut at the base and left directly on the mulched beds. Another layer of mulch is added to cover the plant residues. By the following springtime, most of the plants have decomposed. As the beds have already received a dose of compost, it is not necessary to add more compost, with the exception of adding a handful of compost in the transplant hole for demanding plants like brassicas and tomatoes.
Creating new garden beds with layered composting:
We can create new raised-bed gardens by forming a compost pile, allowing it to decompose, and then planting directly into it. This has been popularized as the “lasagna gardening” technique. The ground is covered by thick layers of wet newspaper or cardboard, and then alternate layers of carbon-rich and nitrogen-rich materials are piled on top of each other, about 2 feet high, in your preferred shape and location for a garden bed. The top is covered by a thick layer of mulch, like leaves, so the food scraps are not exposed. If this is done in the fall, the beds are ready for planting the following spring. Or if you start your lasagne garden in the early springtime, the decomposition can be sped up by covering the pile with black plastic for a few weeks.
This method ainvolves large amounts of organic matter. You may need to seek out additional organic matter from neighbours in order to have sizeable beds, which will help divert their leaves and food scraps from the landfill, while fertilizing your gardens with a low-maintenance technique. This type of composting allows us to start new gardens without ever tilling or digging the soil, and is even a way of establishing garden beds on poor soils or paved surfaces (note: in the case of paved or contaminated surfaces, add a geomembrane on the surface before adding your newspaper and organic material, to separate your garden from any ground contaminants). Over the course of the season, the height of the garden beds will reduce significantly with the decomposition process: add more organic matter at the end of each season!
Heaps and windrows
Quite simply, we can compost by forming a heap with alternating layers of “green” and “brown” materials. Composting in heaps is especially appropriate for farms, as large amounts of organic material can be composted, and they allow significant flexibility as the size and location of the compost heaps can change over time. Heaps can also be suitable for home gardeners with large backyards; though in areas with small and crowded backyards, container composts may be more suitable.
Ideally, each heap should be at least 1 metre high and 1 m wide, as this generates heat and speeds up the decomposition process. Farms can have multiple compost heaps spread out across the farm, or can centralize their composting by forming windrows. Windrows are simply long heaps: often about 1-2 metres wide, 1 metre high, and many metres long.
Compost heaps and windrows can be turned by hand, or with machines, depending on the scale and the available equipment. Heaps can be turned by hand with pitchforks by forking a new heap to the side. Tractors and loaders can be used with shovel or forklift attachments, and there even exists speciality equipment specifically for turning and aerating windrows. Turn the heap at least once a year to mix up the organic material, and more frequently for faster decomposition.
The heaps and windrows can be shaped with a triangular peak to shed rainwater. Though it’s even better to keep them covered with a geotextile, which will keep rainwater from bogging down the compost, and will also allow oxygen pass for aeration. Plastic tarps can be used, but they’re more problematic because they can block oxygen, which makes it more likely that the heap will compost poorly and smell. Some farms cover the heap with a thick layer of straw or leaves.
Composting in containers is a classic practice for people who compost in cities, and can also be done on farms. Containers have several advantages: the lids keep out the rain; the containers deter scavengers; the containers allow us to pile the compost higher while taking up a relatively small surface area; and they keep the compost area looking tidy.
You can build a compost container yourself, and there are numerous possible models. Often compost containers are built with wood, which can be coated with linseed oil for extra protection from the elements (note: avoid any chemically treated wood). Small-scale containers include modifying an old garbage bin or modeling a compost container out of wire mesh. Large-scale models include stacking concrete blocks to form a frame, or building a container with reclaimed construction materials. At Tolhurst Organic Produce, a Stockfree Organic farm in England, their compost heap is enclosed by 3 walls formed by straw bales, which can later be composted themselves. Simply search “DIY compost bin” on the internet, and choose the model that best suits your needs and available materials. It’s important to ensure that the compost bin has air flow along the sides, and ideally direct contact with the soil. On the top, use a lid, roof, geotextile or thick layer of straw or leaves to prevent nutrient loss from the rain.
There are many different types compost bins available for purchase, with varying materials, sizes, and costs. The main materials are plastic or untreated wood. In the spirit of nutrient cycling and renewable materials, we’re in favor of wooden composts, which will eventually decompose themselves. We’d also recommend bins where the composting materials have direct contact with the earth, as this allows for better decomposition through interaction with the organisms that live in the soil. Some municipalities offer rebate programs on compost bins for their local citizens, or environmental non-profits may offer compost bins at reduced cost.
Especially for larger-scale composting, it’s best to have at least two containers: an “active” bin for adding new organic material, and a “dormant” bin where the compost matures. When the mature compost is ready to be used, empty the dormant bin with a pitchfork. You can pass the compost through a screen to remove any large uncomposted chunks, and store the compost in buckets or bags away from the rain if it won’t be used immediately. Then, use a pitchfork to transfer everything from the active bin to the dormant bin. This will turn and aerate the organic material, which can then be left for several months to mature. In the meantime, you can re-fill the active bin.
For small home-scale composts, there is often only one container, where the mature compost can be removed by hand from the bottom through a trap door.
When choosing the size of the bin we need, we can perform a “waste audit” in advance to estimate the amount of organic material we’ll be adding to the bin. Or, alternately, we can choose the size of the bin based on our needs in mature compost. If our compost bins have a volume of at least 1 cubic meter, this will generate far more heat and speed up the decomposition process. Smaller volumes will still decompose, though the process will be slower.
All compost bins can be aerated on occasion by creating air tunnels with a stick or compost aerator, or by mixing it up a little with a pitchfork.
Community composting is an interesting option for composting collectively with others in our neighborhood. Community composts are especially suited to neighborhoods where there isn’t appropriate space for individual backyard composts, such as apartment blocks or residential areas surrounded by asphalt. Community composts have the advantage of making composting accessible regardless of land access. For more information, read our complete article about community composting.
Balcony, indoor, Bokashi
For home gardeners who simply don’t have the land access needed for a backyard compost, there are options for creating veganic composts on balconies, rooftops, and even indoors. These methods may be trickier and lower volume than backyard composts, so given a choice we’d recommend a normal backyard composter. Though for people with limited land access, these are great ways to divert your food scraps from the landfill and create compost that can be used in balcony and rooftop gardens.
Balcony or rooftop compost:
A versatile model for balcony composts was devised by veganic gardener Marco Pagliarulo, and it doubles as a container garden! The concept is quite simple: a bottomless bucket is nestled inside of a larger container. Inside the bottomless bucket, finely-cut food scraps and brown leaves are mixed together, which slowly break down into compost. Between the bucket and the container, soil is added and plants are grown. These plants are automatically nourished by the compost that seeps out of the bottomless bucket. A trap door is added at the bottom of the larger container, so that the composted material can later be removed by hand. For full details and DIY instructions, see our article about balcony composting.
Bokashi is not actually a form of composting, though it provides another avenue for preparing organic waste for the garden. Like composting, Bokashi transforms waste organic material with the help of microorganisms. But unlike composting, Bokashi involves a fermentation process (anaerobically, without oxygen), rather than a decomposition process (aerobically, with oxygen). Whereas composting gives an end result that looks like dirt, Bokashi gives an end result that is similar to pickled foods (like sauerkraut and pickles). After two weeks of fermentation, the organic waste can be buried a few inches down in garden or added to a compost bin, where it will then decompose.
Bokashi is typically fermented in buckets, and involves the regular addition of EM (effective microorganisms). Detailed instructions can be found here. An advantage of Bokashi is that it allows us to manage organic waste in indoor environments in a way that is compact and odour-free if properly managed. This makes it especially suitable for apartments or other small dwellings. It’s also appropriate for the wintertime when other options for managing organic matter may be less feasible, and it can be used as a secondary method of managing organic waste if our compost bin is full. A disadvantage of Bokashi is that the fermentation process creates natural acids (like pickles), so it can only be added to the soil in small quantities, and wouldn’t be appropriate for adding to seedling mixtures, making it less versatile than true compost.