Composting Methods 1: Indoor

For people who decide to start composting their organic waste, the choice of what method to use can be overwhelming. A successful composting journey, however, starts by picking a method that will work for your lifestyle and composting goals. To keep yourself from becoming frustrated, it’s important to first evaluate how much time and space you have to devote to composting. Also consider what materials you produce, whether you have pests like raccoons you need to guard against, and whether you want to compost through the winter. Weighing your needs against the features of each composting method will help you decide which to choose. 

Indoor composters are primarily designed to deal with kitchen scraps and other food waste. They can be used year-round and are great for apartments, offices, and other locations that lack outdoor space. They are also often used in conjunction with outdoor systems to take advantage of the benefits of each. While you can simply take a container and construct an indoor compost pile in the same way you would an outdoor pile, it’s very difficult to achieve the right balance of materials, moisture, and oxygen. An unbalanced pile tends to produce foul-smelling methane and attract pests, which are side effects which are generally not welcome indoors. Specialized indoor composting techniques bypass those complications, however, allowing you to peacefully coexist with your decomposing food.

Worm castings are dark, crumbly, and full of nutrients.

Worm Bins

Worm bins are by far the most popular method of indoor composting. As the name suggests, worm bins are typically a container or series of containers housing a colony of worms. While they use carbon rich materials like shredded paper as their bedding (as well as an occasional snack), the worms are primarily a way to turn your nitrogen-heavy food scraps into rich worm castings. If you’re feeding your worms right, the process is odor free and suitable for small apartments and enclosed spaces. There are a few foods that shouldn’t be fed to the worms, though. Meat, dairy, and fats can go rancid before the worms get to them and also tend to attract pests. Alliums, like onions and garlic, and brassicas, like cabbage and broccoli, are naturally strong-smelling and create even more odor when decomposing. Spicy food and citrus can also be harmful. These limitations can be the main reason not to use a worm bin—if you can’t produce enough worm-friendly food scraps, the worms will starve!

Electric Composters

There are several models of electric composters available; these grind up food waste and heat it up to speed decomposition, resulting in finished compost in just a couple weeks. Unlike the majority of compost methods, you can include meat, bones, dairy, and oils, as long as the quantities aren’t too great. While these appliances are fast and odorless, they do tend to be noisy as they grind and turn the food scraps.They also use energy, which can be a downside for those trying to lower their carbon footprint. And on top of paying for the electricity to run the composter, the units themselves are quite expensive, starting around $300.

Bokashi

Bokashi is a relatively new home-composting technique. It uses an airtight bucket and a blend of microbes to ferment food scraps. Food waste is added to the bucket and sprinkled with a dry material, commonly referred to as bran after the most popular choice of substrate, that has been inoculated with microbes. The bran is added every time scraps are until the bucket is full, at which point the sealed bucket is put aside for two weeks to ensure that all the material is fully fermented. Waste liquid, which can be diluted and used as fertilizer, should be regularly drained off while the bucket is being filled and during the final two-week curing process. The finished product with bokashi is often referred to as “pre-compost” as it has not broken down into crumbly, dark brown material. The nutrient- and microbe-rich material can be incorporated into an existing outdoor compost pile or buried in fallow ground, where it will rapidly decompose into finished compost in just a couple weeks.

While bokashi fermentation is an anaerobic process, it is different from the methane-producing anaerobic decomposition that occurs in landfills and soggy compost piles. Bokashi instead has a slightly acrid pickled odor, like sauerkraut or kimchi. The airtight bucket contains these odors, however, except when the lid is opened to add material. Because of the nature of the fermentation process, it is safe to compost dairy, fats, and even small amounts of meat and bones. Unlike worm bins, you can feed your bokashi bin as little or as much as you produce, simply adding bokashi bran as necessary. The necessity of burying the bokashi can be challenging for those with no outdoor space, but the compost can be finished in a soil-filled bin or even gifted to a fellow composter or community garden.

Introduction to Compost

If you are interested in becoming more self-sufficient, growing your own food, producing less waste, and lowering your carbon footprint, composting at home can help with all of those objectives. Compost is not a new idea. Beyond the fact that human cultures have been producing and using compost for centuries (if not millennia), Mother Nature has been composting for as long as organic matter has existed.

What is compost? It’s simply decomposed organic matter. All organic matter decomposes eventually, but composting generally involves techniques that harness natural processes to speed up decomposition. The final product is dark, crumbly, earthy-smelling, and full of nutrients and microorganisms that are beneficial to plants.

Finished compost is dark and crumbly.

When many people think of compost, they think of worms. And while worms are certainly one decomposer—in fact, one method of composting relies exclusively on worms—they are a relatively minor part of the decomposition process. Worms and other creatures like snails, millipedes, sow bugs, and some types of nematodes, and fly larvae are all visible organisms that work on decomposing the organic material in your compost pile, but the powerhouses are all much smaller. Microorganisms such as fungi, bacteria, and actinomycetes (an unusual bacteria that forms colonies like a fungus) exist in such huge quantities that they are able to break down organic matter at a much faster rate than their larger counterparts, often without you ever seeing them.

Also surprising to most people are the extreme temperatures at which decomposers work. A class of bacteria known as psychrophiles are active at temperatures all the way down to 0°F, although they’re most effective around 55°F. As they oxidize organic material, they produce heat. If your compost pile is large enough to retain this heat, it becomes habitable by the mesophiles. These are your everyday bacteria that survive temperatures from about 40°F to 110°F, with the active range between 70°F to 90°F. Mesophiles are much more effective composters than psychrophiles, and they further warm up the pile to introduce yet another class of bacteria: the thermophiles.

Thermophilic bacteria are rapid decomposers that operate from 100°F up to as much as 200°F, though most home compost piles peak between 160°F and 180°F. These high temperatures will kill weed seeds and pathogens in the compost, which is especially important in commercial composting facilities. Temperatures will naturally drop again after 3-5 days as the bacteria use up their resources, but the process can be restarted by turning the compost pile to aerate and add necessary moisture. It takes a delicate balance of ingredients to reach the thermophilic stage, but mesophilic composting is still quite effective and much easier to accomplish.

Your finished compost will support a complex food web including many of the same macro and microorganisms that aided in the decomposition process. It will also be pH neutral, as the decomposition process buffers acidic or alkaline material. No matter what the original material, the compost will be dark and crumbly and smell like earth. There are often some materials, such as larger chunks of wood or fruit rinds, that don’t completely compost by the time the rest of the pile is finished; these can be screened out and added to the next compost pile. The finished compost can then be applied to your landscape plants and produce, adding vital nutrients to help you grow your next round of compost ingredients.