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.”
The project has its origins in Ethiopia, where researchers led by Johannes Lehmann, the Liberty Hyde Bailey Professor of Soil Science, have been working to improve smallholder agriculture by recycling farm and municipal resources to make fertilizers that are high in phosphorus or nitrogen.
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Image: Rachel Hestrin, Ph.D. ’18, and collaborators from Jimma University visit a facility built to conduct compost experiments in Ethiopia. (Credit: Worku Chibssa/CARE-International)