From Table to Garden: Composting 101

Soil is one of the most important things to consider when gardening. But even once you have found the right type of soil, after multiple planting seasons the soil eventually loses its nutrients and becomes less productive. Fortunately, there is a free and easy way to nurture your soil back to health: composting. Composting often gets a bad rap as something that smells bad or attracts tonnes of pests. But if done correctly composting does not have any downsides, and has many benefits for the environment and your soil!

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The Composting Basics

By definition, compost is an aerobic (oxygen-required) process in which organic matter is broken down into a nutrient-rich soil amendment. However, if you just throw your green bin waste in a composter, you likely won’t get very useful compost. Proper composting requires balancing your greens (nitrogen-rich matter) with your browns (carbon-rich matter). The average ratio is 2:1 for browns and greens, respectively(however other factors may complicate this). You can go outside this ratio by a fairly large amount and still get good results; the process may simply be slower. You should note that if your compost is smelly or wet, you likely have too many greens; if it is dry, you likely have too many browns. Both cases can be fixed by adding more of the opposite component. Carbon and nitrogen are both important for healthy plant growth. On one hand, carbon promotes a soil structure that holds water and allows oxygen to flow through. On the other hand, nitrogen promotes foliage growth in plants. Too much of either can cause various problems for the plant.

Plant matter plays the role of both a green and a brown. When the plant waste is fresh, it contains lots of nitrogen and moisture, but as it dries, it loses most of that and becomes predominantly carbon. While the waste is not gaining carbon as it loses nitrogen, the fact that it dries out is also important. Otherwise, the compost would be soggy from all the moisture released as the greens decompose.

There are some things you can compost, but for a variety of reasons should not. Meats, fats/oils, and dairy all compost in a very odorous fashion, which also makes them pest magnets. Waste from carnivorous animals, like dogs and cats, breeds many dangerous pathogens, but waste from any herbivore is safe. However, dog and cat fur are a good and safe source of nitrogen and repels pests.

When it comes to the actual composting itself, it can be useful to break up compostable matter into smaller parts, the increased surface area will allow bacteria and other detritivores to break down the waste considerably faster. Woody waste can easily be crushed with a spade or shovel. This is especially important with large pieces as they will otherwise take several years to compost. Small branches can be cut up with a shear. I also personally find it helpful to have a separate bin for green bin waste and compost waste, that way you don’t have to sort the waste by hand.

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Any vegetable waste can be used to make healthy compost. Image credits: https://media.greenmatters.com/brand-img/ItPnJ/0x0/what-is-composting-1539283210573-1539283216657.jpg)

Composter types

When it comes to composting, there are 4 types of composters: bin, tumbler, pile, and vermicomposter.

Bin composter

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Tumbler composter

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Compost pile

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Vermicomposter

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Bin composters are simply bins placed on the ground. You simply put your compost in the bin and let it pile up. Occasionally it can be useful to stir the compost with an aerator to mix up the browns and greens and allow for better oxygen flow (which is important for the microorganisms doing the digesting. Your finished compost will end up at the bottom of the bin, there is a latch that opens up for ease of access. Many of these composters are sold during certain months by various municipalities. Check if yours has a program!

Tumbler composters are rotatable drums. They are generally raised above the ground, and further lower the pest risks as they are hard to get into. This composter needs to be rotated daily. But the fact that all the compost is mixed, means much more oxygen flows through. This is by far the fastest way to compost, but it also is the most work. Since this composter is above the ground, it is harder for microorganisms to colonize.It is therefore recommended to put some soil or old compost in to create a starter population to spread through the barrel. It should be noted that because these are sealed, there is less evaporation and the compost is prone to getting soggy.

A compost pile is by far the cheapest method and consists of piling up the compost. It is important not to have the greens on the top of the pile, otherwise you will get many pests. An aerator is also helpful for this type of composter.

A vermicomposter uses mainly worms to produce compost. Most of this compost is made up of worm poop (otherwise known as castings). There are many types of vermicomposters but the simplest is a bin with holes in it allowing oxygen for the worms to breathe. In addition to regular composting, worm composters require a bedding layer for the worms to live in (it can be made up of a combination of any of the following: cut-up corrugated cardboard, cut-up unbleached white paper, brown leaves, or coco coir. Bedding materials are not in one layer but rather mixed into the compost and added continuously. Unlike traditional composting, it is important not to overfeed the worms. If worms are trying to escape the bin that is a good sign something is wrong, luckily there are a variety of online resources available to help identify the problem. Vermiposting is useful as you can use more of it to mix into the soil (although above a certain amount, it does not have much use), and does not require any form of aeration as this is done by worms.

Good for the Soil and Good for Nature

While there are many practical reasons for composting, there are environmental ones as well. While many municipalities have some sort of organics collection program, these materials are only sometimes composted. In Ontario, for example in 2015, over 60% of its food waste was landfilled. When waste piles up in a landfill and is not aerated, certain microbes become active and release large amounts of methane into the atmosphere (a potent greenhouse gas 25 times stronger than CO₂) as they decompose organic matter. Composting at home keeps the compost aerated, which keeps these methane-producing microbes dormant. Another advantage of composting at home is that you are reducing the distance that waste needs to travel and any emissions associated with that travel. In addition, by composting, you are reducing your reliance on fertilizers often made from harmful chemicals or fossil fuel byproducts.

So, next time you finish that banana or orange, don’t just throw it out, compost it. Your soil and the planet will thank you! Stay tuned for more.