U.S.-FocUSed Biochar report - BioEnergy Lists

an efficiency of 32% and conventional soil carbon sequestration in soils is about 14%. The U.S. 2007 Energy Independenceand Security Act states that cellulosic biofuels (such as ethanol made from cellulose) must, when bothdirect and indirect emission are taken into account, offer at least a 60% lifecycle greenhouse gas (GHG) reductionrelative to conventional gasoline (cited in Tilman et al. 2009). According to Strand and Benford (2009) theburial of crop residues in the deep ocean is the only method to process large amounts of carbon, be repeatable,sequester carbon for thousands of years, be practical, economical (337.5 US$ Mg -1 of carbon) and be implementedsoon. Carbonization of biomass and the storage of carbon in the form of charcoal (biochar) was suggested bySeifritz (1993). However these proposals neglect the removal of essential nutrients contained in the biomass andthe beneficial effects of carbon on soil fertility. Seiftiz did not know about the beneficial effects of charred plantmaterial on soil fertility and that a significant proportion of SOC in Chernozems or Mollisols consists of suchcarbonized plant matter (Skjemstad et al. 2002). The recalcitrance of carbonized plant matter makes it needlessand therefore wasteful to protect this form of carbon in ocean sediments or landfills. Pyrolysis of waste biomassgenerates fuels and biochar recalcitrant against decomposition. Returning the carbon and nutrients to the landin form of biochar would offer unique options to address issues emerging from the conflicting and complimentarypositions of cultivated crops including; energy, CO 2 sequestration; or, for food and fiber. The residual biocharstill contains a significant proportion of the energy contained in the feedstock. Not utilizing the charcoal forenergy generation but instead using it as biochar (non-fuel use) holds an opportunity costs. Some of the valuesadded are; increased sustainability of land use, a large carbon sink, and reduced competition between differentland use purposes through waste biomass utilization. Biofuels should make a positive impact on energy security,greenhouse gas emissions, biodiversity, and should not compete with food production (Searchinger et al. 2008;Tilman et al. 2009).Biochar and Soil FertilityBefore the introduction of mineral fertilizers a complex crop rotation and fallow system was established in orderto maintain SOC; nutrient cycling and SOC conservation was of prime importance. Today however even mineralfertilized fields show yield decreases, reduced nutrient cycling and reduced nutrient-use efficiency of appliedfertilizer if SOC declines (Grace et al. 1995; Yamoah et al. 2002). As opposed to the traditional mineral fertilizerpractice described above, soils containing charred plant materials are among the most productive soils in theworld. High levels of charcoal carbon resulting from repeated historical burning of grasslands, open woodlands,and agricultural crop residues have been reported in soils from Australia and Germany. As the SOC pool declinesdue to cultivation, the more resistant charcoal fraction increases as a portion of the total carbon pool (Zech andGuggenberger 1996; Skjemstad 2001; Skjemstad et al. 2002). In U.S. agricultural soils charcoal constitutes up to35% of the total SOC (Skjemstad et al. 2002). However only a small percentage of the original carbon remains inthe form of charcoal after a forest fire (Fearnside et al. 2001).Most impressive is the transformation of one of the world’s most infertile soils into one of the most productiveones in the Brazilian Amazon. If either anthropic (unintentionally formed) or anthropogenic (intentionallyformed), these dark soils are the product of human activities and termed Terra Preta de Índio. The depositionof nutrient-rich materials and charcoal within the zone of habitation and associated garden areas created thesesoils (Woods 1995). The resulting soil contains high concentrations of charcoal (Glaser et al. 2001); significantlymore plant available nutrients than in the surrounding Oxisols (Lima et al. 2002). Terra Preta soils still containelevated carbon contents, despite their age of 500 to 2,500 years (Neves et al. 2003) and intensive cultivation.With certainty charcoal was intentionally used in U.S. and European agriculture. The book “Brief Compend ofAmerican Agriculture” published in 1847 mentions multiple uses of charcoal mainly for nutrient (nitrogen) conservationpurposes (Allen 1847). The author recommends the mixing of nutrient rich materials such as guanowith charcoal in order to absorb ammonia. Even human excrements were mixed with charcoal dust and used toreplenish nutrients in the field. It is mentioned that a dressing of charcoal has been found so beneficial that it hasbeen extensively introduced in France. Probably the oldest description of charcoal use in agriculture comes fromJapan. In 1697 Yasusada Miyazaki termed it “fire manure” and described roasting organic wastes and mixing withBiochar in agricultural and forestry applications in:Biochar from Agricultural and Forestry Residues – A Complimentary Use of “Waste” Biomass3