Decoding the Essentials: What Does Compost Consist Of?

What Does Compost Consist Of?

The Basics of Composting

Composting is the process of decomposing organic matter into a nutrient-rich soil amendment called compost. It’s an eco-friendly way to recycle kitchen scraps, yard waste, and other organic materials instead of sending them to landfills. Understanding what compost consists of can help you create a successful composting system at home and make the most out of your waste.

Organic Matter

At its core, compost primarily consists of organic matter. Organic matter refers to any material that was once alive or produced by living organisms. This includes fruit and vegetable peels, coffee grounds, eggshells, yard trimmings like grass clippings and leaves, straw or hay, shredded newspaper or cardboard, plant-based food scraps such as potato skins or lettuce leaves – essentially anything biodegradable.

Browns vs Greens

When creating a balanced compost pile it’s important to maintain the right ratio between carbon-rich “browns” and nitrogen-rich “greens.” Browns refer to dry materials like dried leaves or twigs while greens are fresh items rich in nitrogen like food scraps or freshly-cut grass clippings.

Mixing Ratio

Achieving the ideal mix means using about three parts browns for every one part green material by volume. This balance ensures proper decomposition without attracting pests or producing unpleasant odors. Experiment with different ratios until you find what works best for your specific compost pile.

Air and Water

Alongside organic materials in your composter need air (oxygen) and water to break down effectively. Microorganisms responsible for decomposition require oxygen to thrive; therefore it is crucial not to pack your composter too tightly but rather allow airflow within it.

Similarly important is maintaining adequate moisture levels throughout the composting process. The material should be damp, similar to a wrung-out sponge. If it’s too dry, decomposition slows down; if it’s too wet, anaerobic bacteria may take over and produce unpleasant smells.

The Role of Microorganisms

Microorganisms are nature’s recyclers and play a vital role in breaking down organic matter into compost. Bacteria, fungi, worms (vermicomposting), and other tiny organisms work together to transform materials into nutrient-rich humus that can nourish plants.


Bacteria are the primary decomposers responsible for breaking down complex organic compounds in compost heaps. They thrive in warm temperatures between 135-160°F (57-71°C) during the “hot” phase of composting when rapid decomposition occurs.


Fungi help break down tough materials such as wood chips or straw which bacteria alone struggle with. They create mycelium networks that access hard-to-reach nutrients within the pile.


In vermicomposting or worm composting systems, worms like red wigglers assist in speeding up decomposition by consuming organic waste and excreting castings rich in beneficial microorganisms and plant nutrients.

Final Thoughts on Compost Composition

Compost consists primarily of organic matter sourced from kitchen scraps and yard waste. Achieving an appropriate balance between carbon-rich browns (dry materials) and nitrogen-rich greens (fresh items) is crucial for successful composting. Adequate airflow, moisture levels, as well as the vital role played by microorganisms such as bacteria, fungi, and worms contribute to the breakdown process leading to nutrient-rich humus ready for use in your garden or potted plants.

By understanding what makes up compost at its core level—organic matter mixed with air/water and aided by microorganisms—you can take full advantage of this natural recycling process while reducing waste and nourishing your plants in a sustainable way.