U.S.-FocUSed Biochar report - BioEnergy Lists

y aerial survey. The mountain pine beetle is responsible for 50 percent of the detected mortality. It was estimatedthat more than 23 million ha (58 million acres) will have more than 25% of the standing live volume at riskof mortality within the next 15 years (Oswald and Campbell 2009). Conner and Thompson (2009) estimated thetotal mortality for trees in the U.S to be nearly 221 million m 3 (7.8 billion cubic feet) in 2006. The Rocky Mountainregion showed a decline in net growth since 1996, with mortality 3.5 times higher than the annual rate of growth.In 2006, more than 127 million m 3 (4.5 billion cubic feet) of logging residues was created in the U.S. and left in theforest in the process of harvesting timber. A further unutilized 1.2 million Mg (1.3 million tons) of wood residuesare generated by the timber-processing facilities in the U.S. (Morgan, Johnson, and Piva 2009).Apart from soil fertility improvements, decentralized production and utilization would reduce costs and GHGemissions associated with biomass and biochar transport and has therefore an advantage to co-firing biochar incoal power plants or sequestration of biomass carbon the deep ocean. Currently, most calculations for proposedbiofuel plants limit their collection radius to 65 km (40 mi), a distance more than twice that currently consideredeconomical for sugar cane processing (Karlen et al. 2009). However, costs of collection, pyrolysis and transportationare also a significant hurdle to the economic profitability of larger biochar-pyrolysis systems (Roberts et al.2010).ConsiderationsIssues of SOC and nutrient cycling, crop yield, available water and drought resistance can be addressed with biochar(Laird et al. 2010; Novak, Busscher et al. 2009). However, any practice that involves removal of crop residues,leaving soil unprotected even for a short duration, would increase risks of accelerated erosion (Lal 2008). Accordingto Andrews (2006) crop residues incorporated into the soil (which would apply for biochar) do not provide thesame protection against soil erosion as crop residues left on the soil surface. The relationship between residueremoval weight and resulting soil cover is not linear and needs to be assessed to determine appropriate removalrates. A 30% removal rate resulted in 93% soil cover after residue harvest (Soil Quality National Technology DevelopmentTeam 2006). If 70% of surface residues remain in the field crop residue utilization (without consideringbiochar carbon sequestration) would not increase erosion or runoff (Andrews 2006). The issues of soil erosionand runoff can effectively be addressed with a cover crop, which is considered to be 2.5 times more effective thencrop residue in reducing wind erosion (Soil Quality National Technology Development Team 2006). However therecommended precautions for crop residue removal by Andrews (2006) should be considered with or without biocharcarbon sequestration. These involve determination of sustainable crop residue removal rates and additionalconservation practices such as contour cropping, conservation tillage and cover crops.Research has shown that biochar has significant effects on pesticide sorption (Sheng et al. 2005; Spokas et al.2009; Yu, Ying, and Kookana 2009). This may reduce pesticide leaching into surface and ground water, but theinfluence of biochar on pesticide function and effectiveness might require further assessments.A definition of biochar as carbon rich material should make a clear distinction between biochar and ash. Somemineral rich raw materials (e.g. manures) produce a biochar with high ash content. The impact on SOC is negligibleif such biochars are applied at agronomic fertilization rates (based on phosphorus and potassium requirements).On the other hand, applied at rates to increase SOC levels, the applied phosphorous might negativelyimpact water resources. Losses of nitrogen during pyrloysis of nitrogen rich materials (Gaskin et al. 2008) mayincrease nitrogen fertilization requirements. However nutrient rich materials can be co-composted with biocharin a synergistic way (Steiner et al. 2010). Maximizing nutrient use efficiency would also contribute to reducingcarbon emissions from agricultural systems. About one-third of the energy requirement in U.S. crop productionis caused by nitrogen fertilization (Pimentel, Gardner et al. 2009).Competition with food production and induced land use change would diminish the carbon sequestration potentialeven for a strategy as promising as biochar. Roberts et al. (2010) calculated a small net increase in GHGemissions if switchgrass is purposefully grown for biochar production and the indirect consequences on land8U.S.-Focused Biochar Report:Assessment of Biochar’s Benefits for the United States of America