Biochar, a waste product from the burning of biomass, has tremendous potential as a soil amendment for urban tree care. Biochar has been used for centuries throughout the world for restoration of infertile soils. Urban soils are often deficient in carbon, available nutrients, and biological activity. Because biochar has a high affinity for nutrients and long persistence, it is a superior organic amendment for urban soil restoration. To date, no studies have examined biochar’s impacts on urban trees and soil. The Morton Arboretum Soil Science (MASS) laboratory and Bartlett Tree Research Laboratories have designed three experiments to take a comprehensive look at biochar for urban tree care. These projects will compare biochar to other nutrient amendments (fertilizer, biosolids, compost, mulch, compost tea) in a greenhouse setting with tree seedlings, a nursery setting with five-year-old trees, and an urban landscape setting with street trees 10 to 20 years old. Improvements in soil quality will be quantified by measuring soil physical, chemical, and biological properties (moisture, density, aggregate stability, pH, available macronutrients, microbial diversity, microbial biomass, C respiration, and N mineralization). Tree health will be assessed with above- and belowground biomass measurements, leaf chlorophyll, and leaf C and N contents. Because biochar is a new urban soil amendment, application procedures are currently not available. The research will identify appropriate application rates and procedures for urban tree management with biochar. The research will consider economic and social aspects of biochar as an urban tree care amendment compared to other current practices. This project is funded in part by a TREE Fund Hyland R Johns grant.

ARBOCHAR - Arboriculture and Biochar (2010 - 2013)

Biochar application to street trees in Bucktown area of Chicago, IL by Kelby, Elden, and Bryant.