Adding biochar made from waste leather to farmland soils could offer a host of production benefits whilst boosting carbon storage, according to scientists.
Waste leather dander, a byproduct of the leather processing industry, is typically composed of fine shavings that are removed when leather is buffed and finished.
It mostly consists of collagen, but it can also contain substances used in the tanning process, such as fats, oils and tanning agents, which can make it difficult to dispose of.
However, researchers in China have discovered that heating leather dander to 400°C transforms it into BC-400, a biochar that has more than 18% carbon sequestration content — higher than straw biochar, which usually rages between 10% and 15%.
In trials, when it was added to soil for 60 days, it reduced the soil organic carbon mineralsation rate to just 0.499 mg CO2 per gram per day, meaning less CO2 in the atmosphere and more carbon locked in the soil.
What’s more soil moisture soared to 42.35%, pH levels reached 7.25, and total organic content jumped to 30.94% — improvements that not only lead to healthier soils, but also significantly boost carbon storage potential.
Writing in the Journal of Environmental Chemical Engineering, the researchers said the introduction of BC-400 also improved the soil’s microbial community.
The biochar promoted a the growth of carbon-storing bacteria like Firmicutes, which further enhance the soil carbon’s sequestration capacity and supports long-term soil fertility.
Economic and environmental benefits
Traditional biochar production, which is often reliant on crop waste like straw, can be expensive to produce due to the high temperatures needed (700-900°C).
However, using collagen-rich waste leather dander allows biochar to be produced at much lower temperatures, the researchers added.
This reduces preparation costs and utilises as waste product that would otherwise contribute to environmental pollution: China alone producers 2m tonnes of waste leather dander each year, which typically ends up in incinerates or landfill.
Converting the waste into biochar would not only cut down on disposal costs and environmental impact, but also create a valuable product that enhances soil health and carbon sequestration, the researchers said.
