The honey locust trees that span North St. Clair Street next to downtown’s NBC tower may owe some of their girth to a 2,000-year-old agricultural practice from the Amazon.
In 2011 landscape architect Bernie Jacobs of Jacobs/Ryan Associates, the site’s designers, had recently learned about biochar — a rich, charcoal-black fertilizer made by pyrolysis, or burning without oxygen. Deep in the heart of a burning brush pile, for example, extreme heat separates organic matter into liquids, gas and a solid called biochar. Because there is no oxygen, however, the process creates no carbon dioxide. Instead, biochar traps carbon.
“It seemed like a beautifully ecological and non-chemical fertilizer,” Jacobs said.