Maybe you buy finished compost for your garden or have heard about the many benefits of composting, but do you know how it works? This blog will explore exactly what compost is, the science behind it, and the 7 types of bins that can make it happen. By the end, you’ll be a backyard composting pro. Use the following links to jump to the sections most relevant to you.
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Turning food waste into wealth, composting helps us rethink trash by embracing a natural process. By supporting microorganisms and larger organisms with the perfect conditions, the process of composting can produce something valuable for our garden. To answer the question, how does composting work?, let’s first take a look at what exactly compost is.
What is compost?
Compost is organic matter, like food scraps and grass clippings, that has been broken down by the activity of oxygen, microorganisms, and organisms. The brown, crumbly, slightly sweet-smelling finished compost is a nutrient-rich amendment that can support soil structure and health of garden plants.
The benefits of composting go beyond producing finished compost that can serve as a more sustainable alternative to synthetic fertilizers. It can also help to curb greenhouse gas emissions from food waste. As they decompose in landfill, organic materials, like food and yard waste, produce methane—a greenhouse gas 80 times more potent than carbon dioxide, according to the Natural Resources Defense Council.
Through the process of backyard composting, one can limit their environmental impact through curbing the greenhouse gas emissions associated with their waste. In aerobic environments (where oxygen is present), like a pre-compost bin, methane-producing microbes aren’t present. So, not only does composting create something that can support soil and plants, but it helps to fight climate change, too!
The science of composting: how it actually works
When a banana peel is tossed out with other waste, it will undergo a decomposition process like all organic material. Over time, microorganisms will consume the decaying waste. Composting just speeds up this process by ensuring the ideal environment for these microorganisms to get to work. The result? Nutrient-rich soil (often referred to as “black gold”) that can be used to support garden plants.
What can be composted?
To better understand the composting process, let’s start with an empty compost bin and imagine what can go into it—and what doesn’t belong. A balanced carbon to nitrogen ratio is the main thing to remember to successfully produce finished compost. This entails a proportionate amount of browns (carbon-rich materials) and greens (nitrogen-rich materials): 30 parts carbon for each part nitrogen, by weight.
Some nitrogen-rich materials include:
- Vegetable waste
- Fresh grass clippings
- Egg shells
- Livestock manure
- Coffee grounds
Some carbon-rich materials include:
- Dried yard clippings
- Dead leaves
- Shredded paper
This means that organic waste like coffee grounds, kitchen scraps, grass clippings, tea bags, and yard waste can be considered suitable pre-compost materials, given that these nitrogen-rich materials are balanced with the right amount of dry, typically brown, carbon-rich material (shredded newspaper, cotton rags, etc.).
In addition to balancing this ratio and ensuring proper airflow and moisture levels (wetness of a wrung out sponge), it’s important to recognize that not everything works as composting material. Due to the risk of spreading dangerous pathogens, pet waste is generally not suitable for the natural process of composting—unless special precautions are taken. Similarly, cat litter can be composted in some cases, but special care should be taken to avoid health hazards and leave crystal and clay litters out of the compost bin.
Things that can’t be composted:
- Diseased and weed plants
- Meat and fish (in some cases)
- Dairy products (in some cases)
The composting process
Once you know what to compost, the process of backyard composting can begin! To get a better grasp of the composting process, it’s helpful to know the three most common types, and how they answer the question, how long does compost take?:
- Passive composting: A more relaxed approach where organic waste is piled up and left to slowly break down over a longer period of time (6-12 months)
- Active composting: Creates ideal conditions for thermophilic microorganisms that require oxygen and heat to decompose organic material more quickly (4-6 months)
- Rapid composting: Balancing the ratio of carbon and nitrogen-rich materials can speed up the decomposition process, but as thousands of households have reported, so can an indoor electric composter like Lomi (3-20 hours)!
Across the different types of composting, the decomposition process mostly remains the same. Through mechanical, biological, and chemical processes, organic material—any plant or animal organism that contains carbon—is broken down into smaller components. A successful compost process can be supported by adequate moisture and oxygen levels, temperature, and microorganism and organism activity.
Microorganisms that help
The composting process is typically broken down into three main stages involving two types of microorganisms. According to Cornell University, the microorganisms responsible for breaking down organic matter into carbon dioxide, heat, water, and humus include mesophilic and thermophilic microorganisms.
To start out the compost process, mesophilic microorganisms (those that thrive in temperatures from roughly 68-113°F) break down the organic waste. In doing so, they produce heat, raising the temperature of the compost pile. This encourages activity from heat-loving thermophilic microorganisms, which continue to break down the organic materials into finer and finer pieces.
This second stage of composting, involving the thermophilic microorganisms, can last from just a few days to several months. Because of the higher temperatures, it’s easier for complex carbohydrates, fats, and protein to be broken down in food waste. As these are consumed—and eventually their amounts exhausted—the temperature begins to drop.
Once again dropping below 40°C (113°F), the pre-compost pile again becomes predominated by activity from mesophilic microorganisms. This is the third and final stage of composting, where the remaining organic matter undergoes a process of “curing.” This stage typically lasts for many months until finished compost is produced.
Organisms that help
To break down organic material into usable humus (nutrient rich soil), microorganisms aren’t the only decomposers. They’re joined by a range of organisms that support the decomposition process while producing heat—which enables activity of the mesophilic and thermophilic microorganisms. The organisms involved in the composting process include:
- Bacteria (mesophilic and thermophilic bacteria): smallest living organisms that use enzymes to chemically decompose organic materials (make up 80-90% of microorganisms in the pre-compost pile)
- Actinomycetes: organisms that resemble fungi but are actually bacteria that degrade organic compounds like lignin, cellulose, chitin, and proteins (i.e. wood chips and banana peels)
- Fungi: yeasts and mold that break down complex plant polymers and tough debris during the mesophilic and thermophilic stages of the compost process
- Protozoa: one-celled microscopic animals that live in water droplets and play a minor role in the decomposition of organic matter but also ingest bacteria and fungi
- Rotifers: multicellular microscopic organisms that live in water droplets and feed on compost materials, fungi, and bacteria
With the right conditions, larger organisms like centipedes, worms, pill bugs, and—unfortunately—fruit flies will also break down the food waste, yard waste, and other organic materials in a compost bin or pile.
How does a compost bin work: 7 different types of bins
Backyard composting looks different for different households and the spaces they have available. A range of compost bins can accommodate these differences. Some may prefer a more large-scale composting approach with no bin at all (compost heap). Others may not want to worry about learning how to use a composter, which is why they prefer the ease and convenience of an electric composter.
To help you find the perfect food waste management strategy for you, here are 7 different compost bin styles.
1. Indoor compost bin
While it doesn’t assist with the composting process per se, an indoor container is one of the best types of compost bins to collect food scraps in the kitchen. Oftentimes, it will have a filter to minimize odors and keep pests away.
Try this product: Utopia Kitchen Compost Bin: 1.3-gallon stainless steel bin to collect food scraps. Includes charcoal filter to trap odors
This is great for: Households wanting to collect food scraps before they can be picked up by the local compost collector, or deposited in an outdoor compost pile or bin
2. Compost pile
Generally more associated with the passive process of backyard composting, a compost pile is an outdoor area where food scraps and other organic waste can be piled. The area could be contained by wooden boards, chicken wire, or a commercial container, or nothing at all.
Try this product: GEOBIN: 216-gallon expandable bin that’s open to the elements
This is great for: Large households/farms/homesteads who have the space and time to allow their organic waste to slowly break down (and are okay with the fact it might attract pests)
3. Electric composter
An electric composter can turn food waste and other organic materials into nutrient rich fertilizer in 24 hours or less. Electric composters work by using electricity (and sometimes microorganisms) to create the perfect conditions for organic waste to break down quickly.
Try this product: Lomi Electric Countertop Composter: Breaks down organic waste and some Lomi-approved bioplastics in as little as 4-hours. Some settings can be used to create nutrient-rich dirt that can be used to support garden plants.
This is great for: Households who want to reduce 80% of their trash and who don’t have the time and space to deal with a compost pile and its potential problems
4. Outdoor compost bin
There is a vast range of outdoor composting bins suitable for backyard composting, all varying in capacity and features to support the decomposition process. In addition to requiring outdoor space, a compost bin should be placed on a level, well-drained surface with adequate access to sunlight.
Try this product: VIVOSUN Outdoor Composter: 80-gallon bin with vents to circulate airflow.
This is great for: Households that produce a lot of food and yard waste, don’t need finished compost quickly, and can regularly maintain the compost bin (turn it, check moisture levels, etc.)
5. Compost tumblers
A compost tumbler is a compost bin designed to facilitate easy turning. This ensures that the pre-compost materials get adequate aeration, which helps to speed up the process.
Try this product: FCMP Outdoor Dual Body Tumbling Composter: Two-chamber composter with tightly-sealed doors and grooves to easily turn the composter 5-6 times every couple of days.
This is great for: Households who prefer a higher bin that doesn’t attract pests and is easier to maintain for those with mobility issues.
6. Worm composter
Worm composting entails using hungry worms (like Red Wigglers) to eat food scraps and some other organic waste. In addition to breaking down waste, they produce worm castings (excrement) that is nutrient-rich and can be used as valuable fertilizer.
Try this product: Worm Factory 360: 4-tray system that has a grid bottom for worms to migrate upward to reach newly-added food and a spout at the bottom for liquid compost tea.
This is great for: Households okay with sharing their home (or protected outdoor area) with hundreds of worms and have a place to make use of the worm castings.
7. Bokashi bin
A bokashi bin is a smaller airtight compost bin that uses “bokashi bran,” a microorganism-rich mixture that ferments food scraps and produces compost tea. After it’s been left to ferment, the organic waste can be buried in the yard to finish the compost process.
Try this product: All Seasons Indoor Composter: 5-gallon countertop compost bin with strainer, bokashi bran, and spigot for compost tea.
This is great for: Individuals who don’t have a lot of food waste and gardeners who could make use of the compost tea.
6 beginner resources to learn more about composting
Whether you’ve been dreaming about backyard composting for years or are just now hearing about how beneficial finished compost is, there’s an abundance of resources available. Here are 6 resources that will help to break down (pun intended) the basics of composting and how to get started.
- Composting for Beginners: Easy-to-follow guide about different composting methods, top tips, and the best composting products for beginners
- Composting At Home: Composting background information, how to avoid pests, and benefits of using finished compost
- Home Composting Basics: Answers to top questions about composting, helpful graphics, in-depth look at different phases of the hot composting process, and troubleshooting trips
- The Best Compost Bin for Beginners: Recommendation for countertop, outdoor, worm, tumbling, and minimalist compost bins suitable for those just getting started.
- Outdoor Composting Guide: Helpful composting tips and troubleshooting advice for beginners in urban environments
- What is Compost? Benefits of composting, most popular methods, and more resources for learning about composting
There you have it! You’re now a composting pro and you can share news of this “black gold” with friends and family. We at Lomi believe that all of us can make a difference when it comes to our individual environmental footprints. Hopefully this shed light on the benefits of composting and how simple it can be to get started.
Written by: Heather Seely