What is composting? A guide to starting composting at home

Americans produce around 292 million tons (265.3 million metric tons) of municipal solid waste annually [source: EPA]. Approximately 52% of this waste ends up in landfills, while the rest is either recycled (glass, paper, plastics, metal) or composted (yard waste). But what exactly is compost?

Composting is a process where organic materials — such as grass clippings, pine straw, leaves, food scraps, and even coffee grounds — are converted into valuable fertilizer. This natural decomposition happens through microorganisms, aided by oxygen. You can compost at home affordably, and the end result is a rich product known as compost or humus, which can enhance your garden soil and act as a natural fertilizer.

Composting Science

Composting provides the perfect environment for the natural processes of decomposition and decay. The essentials for composting include:

During the composting process, microorganisms consume organic (carbon-based) waste and break it down into simpler components. This creates a fiber-rich, carbon-loaded humus along with essential inorganic nutrients like nitrogen, phosphorus, and potassium. These microorganisms decompose the material via aerobic respiration, meaning they require oxygen. That's where you come in—they obtain oxygen from the air you add when you turn the compost (we'll cover that in more detail shortly).

Microorganisms also require water to thrive and reproduce. As they respire, they release carbon dioxide and heat. Temperatures within a compost pile can soar to 100 to 150 degrees Fahrenheit (38 to 66 degrees Celsius). By turning and watering the pile regularly, your compost will break down into finished humus within a few weeks.

However, the conditions must be just right for efficient decomposition. You must ensure your compost pile gets:

Why compost?

The primary objective of composting is to reduce the amount of solid waste you produce and prevent it from ending up in municipal landfills, which can also help lower your tax burden. Finished compost can also serve as a natural fertilizer, offering a more eco-friendly alternative to synthetic fertilizers.

Bacteria and fungi play the key role in breaking down the organic material in compost. Single-celled organisms (protozoa), tiny worms (nematodes), and mites consume the bacteria and fungi. In turn, predatory nematodes, predatory mites, and other invertebrates (sowbugs, millipedes, beetles) feed on the protozoa, mites, and nematodes. This interaction helps balance the population of organisms in the compost, enhancing the overall decomposition process.

Creating Compost

Making compost is fairly straightforward once you get the hang of it:

Selecting a Location

Choosing the right spot for your compost pile is a key consideration. You want it far enough from your house, but not so distant that you neglect it. It should also be positioned away from property lines to avoid complaints from neighbors. Check your local housing regulations or homeowners' association rules, as they may have guidelines on compost pile placement. Other things to keep in mind include:

Selecting a Composting Structure

Compost structures can range from a simple pile where you just add the materials and let nature do the rest—this is called passive composting. Passive composting tends to be slower and less efficient than active composting, where you manage the process more regularly.

You can also create more complex compost bins using materials like chicken wire, wood, or concrete blocks. These bins can be straightforward, single-compartment designs where you layer new materials on top, turn the compost often, and collect the finished product from the bottom.

Three-bin composting systems allow you to place new materials in one bin, move partially decomposed compost to the middle bin, and transfer fully decomposed compost to the last bin. It's also helpful to have a cover on the bins to protect from excess rain and prevent the wind from scattering materials.

However, you don't have to build your own compost bin. Many ready-made options are available, including tumblers with handles to make turning the compost easier. There are also multi-level bins for worm composting. Plus, check with your local city or waste management service, as they may offer affordable or even free compost bins.

The right bin for you depends on how much time, effort, and money you're willing to invest in composting, as well as how much compost you intend to produce. Additionally, be mindful of local regulations that might dictate the type of bin you can use.

Here are some materials that are easy to compost:

Food Scraps from the Kitchen

Almost everything you cut up on your chopping board can be composted. This becomes the "green layer" you'll frequently hear about in composting literature. These materials are rich in carbon, which microorganisms need to break down the matter.

Garden Waste

Whenever you work in your garden, toss the resulting waste into the compost bin. This creates the "brown layer", which provides a significant amount of nitrogen, essential for the composting process.

A word of caution: While weeds will eventually decompose and become part of the compost, they are resilient and can be problematic. Home compost piles rarely get hot enough to fully break down weeds, meaning they could end up spreading back into your garden beds, which is definitely not the goal.

The following materials SHOULD NOT BE COMPOSTED:

You may be curious about composting meat, especially since eggs are compostable. However, meat and bones take a long time to break down, particularly in home compost bins. These bins often don't reach high enough temperatures to decompose meat rapidly, meaning it lingers in your compost for an extended period. This prolonged breakdown process leads to unpleasant odors, and eventually, your yard may begin to smell, attracting animals eager to feast on both the meat and the undecomposed greens.

Municipal composting facilities, often operated by cities, reach high enough temperatures to handle meat and bones. Therefore, you can typically compost these materials at the curb through local services.

Care and Feeding of Your Compost

For optimal results, alternate layers of carbon-rich and nitrogen-rich materials, starting with "green" followed by "brown". Add fresh composting material and soil to the top regularly. Keep the compost moist by watering it, and turn it every few days to provide ample oxygen. You can either turn the pile with a pitchfork or shovel, or use a tumbler's handle to mix the contents.

Worm Composting

Worm composting, also known as vermicomposting, helps speed up the composting process. While a compost pile that touches the ground will naturally attract local worms, vermicomposting involves intentionally adding worms to your pile. You can introduce earthworms to the compost, or purchase specialized composting worms.

As you continue adding layers and turning the compost, you mix fresh materials with partially decomposed ones. Smaller particles from the decomposed material will settle at the bottom. Finished compost will emerge from the bottom of the bin. Most purchased bins feature a hatch at the bottom for easy removal of compost, and in three-bin systems, you add fresh materials to the first bin and transfer partially decomposed and finished compost to the second and third bins.

Collect the Finished Compost

In a single-bin system, the finished compost will gather at the bottom, while in a three-bin system, it will be in the third bin. There’s no exact moment to declare compost ‘done’. If it looks finished to you, then it likely is.

Here are some indicators that your compost pile is progressing as it should:

Once the compost has reached maturity, it’s ready for use. Here’s what it can do for you:

Many home gardeners use the compost they create for their own trees and gardens, while others may choose to sell it to local nurseries or fellow gardeners in their community.

Composting in the 21st Century

Composting has evolved significantly in recent years. Today, nearly everyone, regardless of where they live or what they grow, can compost. Whether it's suburban flowerbeds, rooftop herb gardens, or country vegetable plots, all benefit from home composting, which also helps reduce landfill waste.

Many cities now provide curbside composting services. San Francisco pioneered this initiative, and other cities like Portland, Oregon, Seattle, Washington, and Boulder and Denver, Colorado have followed suit. In these areas, residents receive a garbage can, a recycling bin, and a compost bin for yard waste and food scraps. These materials are collected with the regular trash and processed at large composting facilities.

Companies such as CompostNow, WasteNot Compost, and Compost for Life Miami focus on collecting food waste from both residential and commercial properties. In addition to collection services, they sell the compost they produce back to homeowners, creating a beneficial cycle for everyone involved.

Some food establishments provide compostable or biodegradable takeout containers, but these are not suitable for home composting. They are designed to be processed in industrial composting facilities, typically in cities like San Francisco and Portland. In these cities, even greasy pizza boxes can be placed in compost bins.

Why Bother With Composting?

It may seem like a lot of effort for a small amount of soil, but the benefits are numerous. Let's start with something that often goes unmentioned: saving money.

Take Portland, Oregon, as an example, where composting is part of the city's waste management. The green compost bin is collected weekly all year round, just like the recycling bin. In contrast, the garbage bin is picked up only every two weeks. Depending on your household size, that garbage bin fills up quickly. If you put all your waste in the garbage, you'll need a larger bin to handle two weeks' worth, which costs more. By shifting the bulk of your waste to the compost and recycling bins, you can reduce your garbage bin size and save money.

Even if your area doesn't offer citywide composting, most places charge based on bin size. If you're able to compost most of your food waste at home, you could downsize your garbage bin and save a significant amount of money.

On top of that, if you're into gardening, you can save on fertilizer and store-bought compost for your flower beds or vegetable garden. Even if you're not an avid gardener, you can still use your compost on your lawn or around trees at no extra cost.

Composting also helps reduce the amount of waste sent to landfills. Additionally, it benefits plant growth, which in turn boosts oxygen levels in the atmosphere. Plus, there's the rewarding feeling of using homemade fertilizer, created with a little help from helpful insects and worms.