MASTER GARDENER COLUMN: Start composting in support of Earth Day

Composting is probably one of the easiest ways an individual can honor Earth Day, which is to conserve natural resources. But before you start tossing stuff’ in a pile, you need to know a few facts about composting.

Like, what is composting, its benefits, and which materials are good or not good for a compost?

Pat Allen

Composting is a process of breaking down organic materials into a product that improves soil health and fertility, increases nutrient content of soils, promotes higher yields of crops, attracts and feeds diverse life in soils, and suppresses plant diseases and pests.

Decomposition is generated by mixing a ratio of carbon-to-nitrogen. Carbon provides both an energy source and the basic building block making up about 50 percent of the mass of microbial cells. Nitrogen is a crucial component of the proteins, nucleic acids, amino acids, enzymes and coenzymes necessary for cell growth.

Browns provide carbon and fiber, are slow to rot, and generally come from garden wastes such as dead leaves, and shredded branches/twigs.

Greens provide nitrogen and moisture, are quick to rot, and generally come from kitchen wastes such as vegetable waste, fruit scraps, coffee grounds and grass clippings.

Aeration caused by air circulation (oxygen) helps bacteria and other microorganisms breakdown plant material.

Moisture is essential for microbial activity; material pile must be completely
moistened with 50 to 55 percent water.

A mixture between carbon-to-nitrogen ratios, moisture, and aeration generates a well-balanced compost that not only looks and smells like soil but contains rich plant nutrients and essential trace elements.

Additional factors that aid decomposition:

• A pH between 4.2 and 7.2 is best in the beginning; when it rises to between 6.0 and 8.0 compost is finished.

• Temperature between 90- and 140-degrees F helps kill disease organisms and weed seeds and creates an environment necessary for efficient composting.

• Particle size: the smaller the material the faster it decomposes.

• The optimal proportion of brown to green materials averages about 30 parts “brown” (carbon-rich) to 1 part “green” (nitrogen-rich).

• Typically, “wet,” or green materials such as grass clippings, food scraps and plant cuttings contain a higher proportion of nitrogen than “dry,” or brown materials such as wood, paper, and leaves.

The ratio of carbon-to-nitrogen is 2:1 (C:N) layers of browns to greens. Here are a few examples:

•  Browns (carbon): fallen leaves, twigs and branches, wood chips, sawdust or paper products (used napkins, paper towels, newspapers);

• Greens (nitrogen): grass and plant clippings; food scraps (break, crackers, fruit, vegetable, cooked starches, jam/jelly; coffee grounds and tea bags; manure (not dog/cat); or fish tank water.

Never add the following materials: meat or bone scraps; fish scraps; dairy products; fats, oils, or grease; or dog, cat or human feces.

Composting is a gift because its basic elements are given freely from Mother Nature (sun and rain), specific garden, household and farm animal waste.

All you have to do is put these materials in the right order, allow them to get hot, add water at the right time and stir. Happy composting.

For more information, visit the NC State Extension website at

Pat Allen, a Certified Master Gardener volunteer, lives near Oakboro and enjoys composting and recycling every chance she gets.