Biochar in Manure Management
- Johanna Tanhuanpää
- Sep 16
- 2 min read
Updated: Nov 4
You've most likely heard of biochar and it's potential for adding carbon and nutrients to the soil. But what about using biochar in cattle manure management? Using biochar in manure management is a promising strategy to improve nutrient efficiency, reduce environmental losses, enhance soil health, and contribute to sustainability. But it’s not plug-and-play — the outcomes depend strongly on feedstock, production process, manure type, mixing/application method, and local conditions.
Why Use Biochar in Manure Management?
Nutrient retention & reduced losses
One of the big issues with manure application is losses of nitrogen (via ammonia volatilisation, nitrate leaching, denitrification) and phosphorus being locked or lost. For example, only approximately 30–50% of applied N is taken up by crops – considerable amounts are lost.
Biochar, when combined with manure, can help adsorb or retain nutrients (especially ammonium, some nitrate, possibly phosphorus) and thus reduce losses.
Volume / mass reduction, transport & storage benefits
By thermally treating manure (or solids derived from manure) to biochar, you shrink volume/mass, making transport and storage easier in cases where manure nutrient surpluses or transport economics are a challenge.
The densified nutrients in the biochar form means you could more feasibly move phosphorus or other nutrients to where they’re needed rather than always applying locally where there may be surplus.
Soil amendment / long-term benefits
Once applied to soil (either mixed with manure or treated manure + biochar product), benefits may include improved soil physical properties (porosity, water retention), improved microbial activity and improved fertility. For example, in one study, poultry manure + 20% biochar improved total carbon content, dehydrogenase enzyme activity etc.
Also, biochar adds stable carbon to soil, contributing to carbon sequestration, which is an added environmental benefit.
Reduced greenhouse gas (GHG) & odour emissions
Some research indicates that manure‐derived biochar (or manure+biochar systems) can reduce emissions of nitrous oxide (N₂O), methane (CH₄) or ammonia (NH₃) during storage/composting/manure treatment. For example, the manure pyrolysis to biochar paper highlights reduced GHG emissions.
Key considerations & what affects performance
While the potential for using biochar in manure management is good, results depend heavily on how it’s done. Some of the things to keep in mind include the following.
Feedstock and production conditions matter
Manure type (liquid vs solid)
When biochar is added to manure rather than converting manure to biochar, the effects may differ: e.g., manure + biochar in composting or maturation may change microbial activity and nutrient dynamics.
Application rate, combination, timing
The ratio of biochar to manure (or biochar rate in soil) matters. In one study, manure + 10% biochar had different outcomes than manure + 20% biochar.
The physical mixing, incorporation into soil, or the manner of application (top‐dressing vs incorporation) will affect outcomes.
