Composting is a natural process that recycles organic matter into a nutrient-rich soil amendment. A common question is whether everyday items like newspapers can be included in this cycle. Newspapers are generally compostable and can be a valuable addition to a healthy compost pile, relying on microorganisms to break down the materials.
The Chemical Composition of Newspaper
Newspaper is composed primarily of plant fiber, specifically cellulose, which is the main structural component of plant cell walls. This high-fiber content makes newsprint a carbon-rich material, classifying it as a “brown” ingredient in composting terminology. Cellulose serves as an energy source for the microbes that drive the decomposition process.
The paper also contains lignin, a complex polymer that provides structural rigidity. Modern black-and-white newspaper inks are based on soy or other vegetable oils, which are non-toxic and safely consumed by composting organisms. This shift away from older, petroleum-based inks means black newsprint poses no contamination risk to the final soil product.
Preparing Newspaper for the Compost Pile
To ensure the paper breaks down efficiently, it must be prepared to maximize the surface area accessible to microbial action. Adding whole sheets or compacted stacks of newspaper can block the necessary airflow required for aerobic decomposition. Shredding or tearing the paper into strips or small squares is essential to speed up the process and prevent the material from clumping together.
Newspaper is also highly absorbent and should be thoroughly wetted before it is added to the compost heap. Dry paper can create air pockets that impede moisture flow to the surrounding materials, slowing the decomposition rate. The goal is to make the paper moist, similar to a wrung-out sponge, but not completely saturated.
Newspaper’s high carbon content means it must be balanced with nitrogen-rich materials, often called “greens,” such as fresh grass clippings or fruit and vegetable scraps. For optimal microbial activity, a carbon-to-nitrogen (C:N) ratio of approximately 30 parts carbon to 1 part nitrogen is ideal. Adding too much newspaper without balancing it with greens will cause the compost pile to decompose slowly, while an imbalance can lead to the loss of nitrogen as ammonia gas.
Identifying Non-Compostable Newspaper Components
Not all parts of a newspaper are suitable for composting, and certain sections should be removed to maintain the integrity of the pile. Glossy inserts, slick advertisement flyers, and magazine pages must be excluded. These materials are often coated with synthetic finishes that resist microbial breakdown and can contain heavy metal pigments that are harmful to the final compost.
While black ink is safe, heavily colored sections, like those found in comic pages or advertising supplements, should be minimized or avoided entirely. Although many modern color inks are vegetable-based, some may still contain trace amounts of problematic inorganic pigments. Furthermore, any physical contaminants attached to the paper, such as plastic wrappers, rubber bands, or metal staples, must be completely removed before the paper is added to the compost.