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 (Lehmann et al. 2003). Urban soils may be deficient in carbon, available nutrients, and biological activity. Because biochar has a high affinity for nutrients and long persistence, it may be a superior organic amendment for urban soil restoration (Lehmann et al. 2002). To date, no studies have examined biochar’s impacts on urban trees and soil. The MASS laboratory and Bartlett Tree Research Laboratories are performing research to take a comprehensive look at biochar for urban tree care. Projects compare biochar to other nutrient amendments (fertilizer, biosolids, compost, mulch, compost tea) in greenhouse settings with tree seedlings, nursery settings with three to six year-old trees, and urban landscape settings with mature street trees. Improvements in soil quality are 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 is 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 also 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. The PI's on the ARBOCHAR project are B. Scharenbroch and K. Fite. The ARBOCHAR project is funded in part by a TREE Fund Hyland R. Johns Grant.
