Leilah Krounbi, a Ph.D. candidate in the field of crop and soil sciences, is working to develop a surprising solution to the fertilizer needs of farmers in East Africa: pyrolyzed poop. During a recent seminar on campus, Krounbi described her efforts to use pyrolysis – a technique employed in biochar production involving thermal combustion in the absence of oxygen – on fecal material, converting the waste into a sanitized biomass that can be treated with urine to create a fertilizer that is rich in both phosphorus and nitrogen. Given the nutrient-poor soils, insufficient sewage infrastructure and high cost of imported commercial fertilizers in many parts of Africa, Kronubi’s unorthodox idea could address several problems at once.
“The rural dilemma is a dearth of nutrients, including carbon, nitrogen and phosphorus. The urban dilemma is excess nutrients – human waste going to waste,” Krounbi said. “This could provide a way to close the urban-rural nutrient cycle and char away the dilemmas.”
Meanwhile, Johannes Lehmann, professor of crop & soil sciences and a collaborator in Krounbi’s work, has suggested a different approach to the dearth of phosphorus in the developing world. In a recent letter to Nature Geosciences, he and his collaborators suggest using agricultural waste, and in particular the ground-up and pyrolyzed bones of deceased livestock, as a means to organically fill the phosphorus fertilizer gap. The letter cites the example of Ethopia, which, from 2008-2011, produced approximately 192,000 to 330,000 tons of bone waste per year. Recycling of such waste could have yielded up to 58% of Ethiopia’s annual phosphorus needs, or the equivalent of up to $104 million in imported commercial fertilizer.
Lehmann is currently conducting research in collaboration with CARE USA to develop the technique for practical application in Ethiopia.
