Biochar is a carbon-rich material that is distinct from charcoal and other similar materials dueto its use as a soil conditioner to improve soil quality. One factor limiting understanding andvalidation of biochar as a soil conditioner and carbon sink is the lack of long-duration studies inthe field. Such studies are essential, since biochar can be produced from a wide variety of rawmaterials and thermic processes, leading to very diverse products. Most studies are done ingreenhouses; due to costs involved with establishment and monitoring, studies in the field arescarce. This project, a partnership between Embrapa Florestas and Campos VerdesAgroflorestal Ltda., assesses the agricultural and environmental value of biochar produced viaslow pyrolysis in methods recommended by the main groups that have established goodpractices on this topic. Studies are underway to assess the chemical, ecotoxicological, andagricultural characteristics of biochar produced from Eucalyptus urograndis wood. A field studyis also underway on the effect of biochar in eucalyptus plantations, comparing plots with andwithout biochar and two doses of chemical fertilizers (commercial and reduced).