Researchers at the University of Arkansas at Pine Bluff are studying the potential of biochar – a charcoal made from biomass – to reduce the ecological risks associated with common agricultural waste.


According to Hao Chen, PhD, assistant professor for the UAPB Department of Agriculture, the product is increasingly being used throughout the nation as a sustainable soil additive to improve crop yields.


“Agricultural waste, which includes animal manure as well as crop residues, can be a major nuisance for producers,” she said. “If farmers have rice husks or crop stems lying in their field, they commonly either let the plant residue sit or decide to burn it. Either practice releases a lot of greenhouse gasses into the environment.”


Chen said the conversion of agricultural waste to biochar could help producers deal with agricultural waste in a sustainable manner, minimizing the associated carbon dioxide emissions that contribute to climate change. Moreover, biochar can have a positive effect on soil and water quality in a number of other ways.


“Biochar may look like regular charcoal, but it actually captures agricultural chemicals from the local environment,” she said. “The value-added product is produced on a large scale in a few American factories, but it is also easy to make on small farms. For example, some small-scale producers use an oxygen-free tank or burn barrel to turn waste such as peanut hulls, walnut shells or sweet potato stems into biochar.”


Biochar can be added to soil through tilling. After application, the product absorbs pesticides and other chemical byproducts of agricultural production. Biochar improves water quality by ensuring nutrients and chemicals are not leached off the field and into the ground water or nearby bodies of water. It also increases soil health and fertility.


Chen said UAPB research on biochar is conducted in conjunction with the University of Florida. Current projects investigate biochar’s properties as a soil amendment and in relation to pollution absorption/degradation. Researchers are also studying the ability of biochar to sequester antibiotics in the environment.


“Antibiotics are commonly used in agricultural production and have become a huge problem in recent years,” she said. “They are released into the environment in animal manure or from reclaimed irrigation water and have a profoundly negative effect on microorganisms. Biochar applications help ensure antibiotics found in the soil are captured and contained inside the micropores of biochar. Since the micropores are not accessible to microorganisms, the bioavailability and environmental exposure of antibiotics will be largely reduced.”


UAPB project data will be used to determine agricultural best management practices for the use of biochar on a large scale, Chen said. Eventually the product could be an affordable substitute for other waste treatment agents such as active carbon.


Chen said the research furthers UAPB’s land-grant mission by helping make a clean resource available to small producers, who will be able to improve crop yields. At the same time, they will be contributing to overall local environmental protection.


“Biochar as a value-added product is an innovative and increasingly popular way to make agricultural waste profitable and better ensure soil quality and food productivity in the long run,” she said.


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— Will Hehemann is a writer/editor at the UAPB School of Agriculture, Fisheries and Human Sciences.