Backyard composting diverts organic waste from landfills and creates a valuable soil amendment. Successful composting depends on maintaining a specific balance between two main categories of organic matter. Home composters often question the classification of paper products. Determining whether paper is a “brown” or “green” material is important, as its classification dictates how it should be used to maintain equilibrium within the compost pile.
The Core Distinction: Carbon vs. Nitrogen Sources
Successful decomposition relies on microscopic organisms that require a balanced diet of carbon and nitrogen. Materials designated as “browns” are carbon-rich (C) and serve as the microbes’ energy source, providing structure and aeration to the pile. “Greens” are high in nitrogen (N) and provide the protein necessary for microbial growth. Browns include dried leaves and wood chips, while greens include moist materials like grass clippings and food scraps. Clean, untreated paper is composed of cellulose fiber, a complex carbohydrate, classifying it as a “brown” material. Paper has a high carbon-to-nitrogen (C:N) ratio, typically ranging from 125:1 to 180:1. Since the ideal C:N ratio for composting is approximately 30:1, paper is used to balance high-nitrogen materials such as fresh food waste or manure.
Categorizing Different Types of Paper
Not all paper products are suitable for composting; acceptability depends on the presence of contaminants. Acceptable paper items are clean, uncoated, and printed with minimal, non-toxic inks. This includes plain corrugated cardboard, provided plastic tape and labels are removed. Non-glossy newspaper, office paper, and unbleached paper towels are also accepted carbon sources. Conversely, several paper types must be excluded because they introduce harmful chemicals or impede decomposition. Glossy magazines and heavy-duty colored paper should be avoided because inks and coatings often contain heavy metals that contaminate the finished compost. Thermal receipt paper should not be added because it may be coated with Bisphenol A (BPA) or other persistent chemicals. Heavily waxed paper or paper contaminated with food grease, such as saturated pizza boxes, are unsuitable because the wax and fat create a water-resistant barrier that slows microbial breakdown.
Integrating Paper into the Compost Pile
Paper is valuable for balancing moisture, especially when adding wet, high-nitrogen food scraps. To maximize effectiveness and speed decomposition, paper requires proper physical preparation. Tossing whole sheets or large pieces into the pile can cause matting, blocking airflow and creating anaerobic conditions. It is recommended to tear or shred paper into small pieces, such as strips no wider than one inch, before adding them. This increases the surface area for microbial activity, accelerating the consumption of cellulose fibers. The paper must also be thoroughly moistened before layering, as dry paper wicks moisture away and stalls decomposition. Composters should mix prepared paper browns with greens to approach the target C:N ratio of 30:1, typically using three to four parts brown material for every one part green material by volume. Layering paper between wet kitchen scraps is an effective technique, as the dry carbon absorbs excess liquid and helps maintain the necessary porosity for oxygen to flow throughout the pile. This strategic integration prevents the pile from becoming overly dense and assists the microorganisms in converting waste into humus.