A little Compost goes a long way

Compost diverts organic materials from landfills, reducing their environmental impact, including green house gas emissions, and recycles nutrients and organic matter that helps grow trouble-free plants with less water, fertilizer or pesticides!

The best option is always to Prevent Food Waste

Preventing food from going to waste in the first place is the most environmentally beneficial option on the Wasted Food Scale. When food is wasted, all the resources that went into producing, processing, distributing, and preparing that food are wasted too. Learn more about preventing wasted food.

Compost is the best way to dispose of your food waste

Composting wasted food with other organic materials like yard trim produces a valuable, biologically-stable soil amendment. It can be used to build soil health, increase soil water retention, and reduce soil erosion. Producing and using compost recycles organic matter and nutrients that are important for long-term soil health and ecosystem resilience. Learn more about composting and using compost.

Industrial Compost

If you don't have the space to build your own compost pile, King and Snohomish counties provide industrial compost! Take a look at what happens when you put your compost into the curbside pick-up bin:

Help Reduce Contamination in our Compost!

Sometimes it can be hard to tell what is compostable for even the most dedicated among us. So remember that ‘when in doubt, throw it out.’ Below is some advice on a few of the trickier materials can contaminate compost:

Plastic food packaging

Many local restaurants have made the switch to compostable silverware and packaging. While we like this trend, it’s often hard to know what is compostable and what is not.

Cartons

Liquids we buy like milk and juice come in paper cartons that have a lining made of plastic or metal. These liners can’t be removed during composting so these need to be cleaned and sent to recycling instead. There, the paper mills are eventually able to separate the lining from the paper to be able to create new paper!

Produce stickers

These are usually made of plastic and commonly accompany things like vegetables or avocado skins. We should peel these off and throw them out instead of including them in compost since the stickers are so much harder to remove once composting begins.

The Science of Composting

Have you ever wondered what happens in a compost pile, and how your food waste becomes nutrient rich soil?

The materials used go through several transformations: physical, biological, and chemical. There are four main phases of compost: the primary, secondary, finishing, and curing phases.

The Primary Phase (first 2 - 6 weeks): This is when fresh, raw compost has lots of readily available food for microbes. Bacteria grow as the consume sugars, carbohydrates, proteins, and fats. All this microbial activity results in the release of metabolic energy that raises temperatures in the pile. All of this activity is also essential for breaking down odorous compounds in the pile. this is also known as the First Mesophilic Stage.
Secondary Phase (4–10 weeks): Temperatures are high, oxygen demand is decreasing. The composting is managed via turning to provide continued aeration to maintain aerobicity. The microbes work to break down the organics into finer particles, and the higher temperatures are more conducive to breaking down complex carbohydrates, proteins and fats. Due to the high temperatures, this phase is also known as the Thermophilic Phase.
Finishing (1 - 2 months): This phase begins when the available supply of these organic compounds within the compost system are used up. Very little management is required during the finishing stage. Oxygen demand is low, so it can remain fairly aerobic without active aeration as long as the material is not too wet, too dense, or stored in too large a pile. This phase is also known as the Second Mesophilic Stage or Curing Stage.

(Image of stages below is from the NYC Compost project Master Composter Course Manual. Chapter 2: Composting. Page 2-21.)

The three phases of compost as a graph of temperature vs time.

There are a few ways to tell if your compost is ready to use:

It has a pleasant, earthy odor
It’s dark and crumbly
The volume of the pile should have shrunk by about 50%
The temperature of the pile should be around air temperature
The original organic materials should no longer be recognizable, with a few exceptions (larger wood chips, etc.).

The Benefits of Compost

Economic Benefits

By using compost as a soil amendment or mulch, you can cut costs and:

Reduce the use of herbicides
Reduce the use of chemical fertilizers
Support markets for local compost producers
Avoid landfill disposal costs for “green” material
Conserve water – saving on water bills, less time watering

Environmental Benefits

One of the best and easiest things you can do to reduce what goes to the landfill, to grow healthy, sustainable gardens and lawns, and to discourage chemical runoff into our waterways. In general, the benefits from using compost as a soil amendment or mulch are:

Increased soil fertility
Improved soil structure: increased resistance to erosion and runoff
Increased water holding capacity (i.e. water conservation)
Improved disease resistance in plants: less pesticide use

Organic Waste in Landfills Increases Atmospheric Greenhouse Gas concentrations!

When compostable waste goes to a landfill, it gets buried under massive amounts of other trash, cutting off a regular supply of oxygen for the decomposers. The waste then ends up undergoing anaerobic decomposition, being broken down by organisms that can live without free-flowing oxygen. During anaerobic decomposition, biogas is created as a by-product. This biogas is roughly 50 percent methane and 50 percent carbon dioxide, both of which are potent greenhouse gases, with methane being 28 to 36 times more effective than CO2 at trapping heat in the atmosphere over a century. Although most modern landfills have methane capture systems, these do not capture all of the gas; according to the EPA, landfills are the third-largest source of human-generated methane emissions in the United States.

Learn More about Reducing Waster and Composting from these Resources

The Environmental Protection Agency: Composting

UN Environment Programme: How composting can reduce our impact on the planet

Natural Resources Defense Council: Composting 101

The Story of Stuff Project

Learn More about Healthy Soil

Watch & Learn

Remothering the Land - Watch Now - DCEFF

Three Sisters: Companion Planting of North American Indigenous Peoples

The term ‘Three Sisters’ refers to corn (Zea mays), beans (Phaseolus vulgaris), and squash (Cucurbita spp.) grown together in an ancient Indigenous American companion planting scheme. Each crop complements the others so that growing the plants together provides greater benefits than planting them as single crops. The harvested products are also complementary in a nutritional sense, with the corn providing carbohydrates, the beans furnishing protein, and the squash adding vitamins to the diet.

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