Biochar soaks up ammonia pollution, study shows

A new Cornell-led study shows that pyrogenic matter, also known as biochar, is chock-full of potential as a fertilizer because of its ability to soak up nitrogen from the air pollutant ammonia. And it does so in a surprising way: through a chemical reaction that forms covalent bonds far stronger than those found in electrostatic interactions.

“Balancing nitrogen management so that we provide enough nitrogen to our crops … without contributing to air and water pollution is a major challenge,” said Rachel Hestrin, Ph.D. ’18, first author on the paper, “Fire-Derived Organic Matter Retains Ammonia Through Covalent Bond Formation,” which published Feb. 8 in Nature Communications.

“As nitrogen-rich materials like animal manure break down, a lot of nitrogen can volatilize into the atmosphere as ammonia gas,” she said. “That represents a huge loss of a valuable nutrient from the agricultural system. It could also affect biodiversity if that ammonia is deposited in natural ecosystems and alters nutrient availability there.”

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