Hair is a commonly discarded organic material, yet it is a beneficial addition to any home composting system. Many people overlook hair as a potential resource, treating clippings from haircuts or strands from a brush as simple trash. This organic waste, which includes both human and pet hair, creates nutrient-rich compost that improves soil health. By understanding the composition of hair and following a few practical steps, you can easily divert this material from the landfill and transform it into a premium soil amendment.
The Compost Value of Keratin
The scientific reason hair is valuable in compost lies in its primary structural component: keratin. Keratin is a fibrous protein that makes up about 95% of the hair’s mass. This protein structure results in a high concentration of nitrogen by weight, often ranging between 13% and 16%.
This high nitrogen content classifies hair as a “green” material, fueling microbial growth and activity. Nitrogen is necessary for the microorganisms that decompose organic matter to build proteins and reproduce.
Hair possesses a naturally low carbon-to-nitrogen (C:N) ratio, approximately 3:1. This makes it a potent nitrogen source that must be balanced against high-carbon, or “brown,” materials like wood chips or dried leaves. A balanced compost pile requires an overall C:N ratio closer to 25:1 or 30:1 for efficient decomposition. This balance ensures microorganisms have both the building blocks (nitrogen) and the energy source (carbon) required.
Preparing Hair for Decomposition
Proper preparation ensures hair integrates well and breaks down efficiently. Long strands tend to clump together, creating dense, water-repellent mats that restrict airflow and slow decomposition.
To maximize the surface area for microorganisms, cut or shred longer hair into small pieces, ideally one to three inches in length. This action accelerates breakdown by giving microbes more access points. Both human hair and pet hair are suitable for composting, though pet fur may break down slightly faster due to its finer texture.
The hair must be thoroughly mixed and spread throughout the compost pile rather than dumped in one large clump. Spreading hair in thin layers prevents the formation of anaerobic pockets, which cause foul odors and stalled decomposition. Because hair is a concentrated nitrogen source, layer it with ample high-carbon materials, such as shredded newspaper, cardboard, or sawdust. This practice helps maintain the necessary C:N ratio, preventing an excess of nitrogen that results in the smell of ammonia.
Managing Slow Break Down and Chemical Treatments
Keratin is a tough, durable protein, making it naturally resistant to rapid degradation. Hair can take significantly longer to fully break down than softer organic waste, sometimes requiring up to a year or more. The breakdown of this fibrous protein depends on specialized microorganisms that produce the enzyme keratinase.
To mitigate this slow breakdown, hot composting methods are most effective, where the internal pile temperature reaches between 40 and 50 degrees Celsius. These elevated temperatures accelerate the activity of keratinase-producing bacteria, which deconstruct the hair’s protein structure. The material’s slow-release nature means it offers a prolonged source of plant nutrition once integrated into the soil.
Another consideration is the presence of chemical treatments, such as dyes, bleaches, or perms. While most studies suggest chemicals in treated hair become diluted and break down during composting, caution is advisable. If the compost is intended for an edible food garden, limit the amount of heavily treated hair or use only untreated hair. Small amounts of treated hair typically pose a low risk when they make up a minor proportion of the compost volume.
Synthetic Fibers
Synthetic fibers, such as those found in wigs or some extensions, are plastic-based and should never be added to a compost pile, as they will not decompose.