Composting and other forms of organic waste management can produce strong odors. For farms, composters, cities, and other facilities, those odors can affect workers, nearby communities, and daily operations.
There is rarely just one cause. Gases such as ammonia and hydrogen sulfide can create odors as organic material breaks down. Moisture, temperature, oxygen, and the type of waste can all affect the amount and type of odor produced. Biochar can help manage some of these problems by capturing certain compounds and improving conditions within compost.
Why Organic Waste Produces Odors
Microbes naturally break down food waste, manure, plant material, and other organic matter. When they have the right amount of air and moisture, this process can work well. When material becomes too wet or does not get enough oxygen, stronger odors can develop.
Ammonia is one common source of odor, especially in materials that contain a lot of nitrogen. Other gases can add to the problem. This means odor control is not just about covering up a smell. Managing the conditions that create these gases can help address the problem at its source.
How Biochar Can Help
Biochar is filled with tiny pores and has a large surface area. Certain gases and nutrients can attach to these surfaces through a process called adsorption. This gives biochar the ability to capture some compounds that might otherwise escape from compost.
Biochar can also change conditions inside a compost pile. Its structure can create more space for air and affect how moisture moves through the material. It can also hold nutrients and provide space for helpful microbes. These changes can support the composting process while helping manage some odor-causing compounds.
These results are specific to the tested materials. A rate that worked with pine biochar and poultry litter, or inoculated wood biochar and municipal waste, should not be transferred directly to another feedstock or facility.
What Research Shows
Research supports the use of biochar for managing certain compost emissions. In one controlled study using poultry litter, a compost treatment containing 20% pine-chip biochar reduced ammonia in emissions by as much as 64%. It also reduced total nitrogen losses by as much as 52%.
This is useful for more than odor control. When nitrogen escapes as ammonia, that nutrient is lost from the compost. Keeping more nitrogen in the material can improve the value of the finished compost. Other research has also explored biochar with municipal waste and as a material for capturing odor-causing compounds.
Why Results Can Vary
Not all biochar is the same. It can be made from wood, agricultural waste, and other biomass. The material used to make it and the way it is produced affect properties such as pore space, pH, particle size, and ash content.
The composting system matters too. Poultry litter, manure, food waste, and other materials break down differently. Moisture, airflow, temperature, and the amount of biochar used can all affect the results. A biochar that works well in one system may need a different rate or approach in another.
A Tool for Better Organic Waste Management
Biochar does not replace good compost management. Moisture, oxygen, temperature, and the mix of materials still need to be managed carefully. Instead, biochar can work alongside these practices to help create better conditions for composting.
Its ability to capture certain compounds, retain nutrients, create pore space, and support microbes makes biochar a useful tool for farms, composters, cities, and other facilities that manage organic waste. Rather than simply covering up odors, biochar can help address some of the conditions and compounds that create them.
