Composition of Compost

Greens

• Organic matter low in carbon, called greens, make up a large portion of compost. Typically green in color, these materials provide the nitrogen to the compost because they have a lower carbon-to-nitrogen ratio than the compost as a whole. The majority of greens come from lawn waste, such as grass clippings, weeds and flowers. The remaining greens include coffee grounds and produce waste, consisting of seeds, peels, pulp and rotted matter.

Browns

• Browns typically make up the same proportion of compost as greens, and they are alternated in layers to balance the chemical composition of the pile. Together, greens and the browns, which have a higher carbon-to-nitrogen ratio than the compost, keep the nitrogen and carbon at the desired 30-1 ratio. The aptly-named browns consist of fibrous, dry or dead material. Browns include fallen leaves, sticks, tea bags, cardboard, newspaper, cotton, lint, hair and egg shells.

Water

• For compost to create and retain the heat necessary to break down the organic materials, the piles must remain damp throughout the layers. Water allows the microbes and insects to thrive inside the pile and aid in decomposition. Water also helps the drier browns begin to break down more quickly. Commercially-purchased compost feels neither damp nor dry, but it holds some fluff and sticks to itself with trace amounts of moisture.

Bugs

• Compost piles have microbes that break down the dying organic matter, and insects, which eat the matter and create another organic material. Compost piles may contain any insects found in soil, such as beetles. They may also have slugs and flies drawn to the rotting green matter. Burying the greens will lessen the attraction, but insects typically are not a problem. Other animals draw to the compost bin if it is not hot enough or if it contains ill-advised materials, such as meats.