U.S.-FocUSed Biochar report - BioEnergy Lists

nutrient rich manures (Miyazaki 1697). Rice husk biochar has been used since the beginning of rice cultivation inAsia (Ogawa 2008). Rice husk biochar was also mixed with nutrient rich materials in order to increase its fertilizingefficiency. A mixture of human waste and charcoal powder was called “haigoe” and was frequently used tofertilize crops (Ogawa 1994). As a result of experience and research, carbonized materials are formally authorizedfor use as soil amendment material in Japan, which is using 27% of its national charcoal production for purposesother than fuel, more than 30.6 percent of which is used in agriculture (Okimori, Ogawa, and Takahashi 2003).Also the recalcitrance of carbonized materials was well known and utilized to increase the durability of wood.In an attempt to recreate Terra Preta, initial biochar research was conducted in the humid tropics. Tropical landuse systems provide unique conditions for biochar carbon sequestration. The humid tropics produce more biomassthan anywhere else and the abundance of “waste” biomass is huge. Decomposition of labile SOC is fast andin strongly weathered tropical soils, SOC plays a major role in sustaining soil productivity. Therefore both, theconditions to produce biochar as well as the benefits of soil biochar applications appear greatest in the humidtropics. As a result slash-and-char was described as an alternative to slash-and-burn (Steiner 2007). Lehmannand Rondon (2006) reviewed 24 studies with soil biochar additions and found improved productivity in all ofthem ranging from 20 to 220% at application rates of 0.4 to 8 Mg carbon ha -1 . Such increases in productivity wereexplained by improving soil chemical, biological and physical properties. Iswaran, Jauhri, and Sen (1979) usedbiochar as carrier material for Rhizobium. The biochar provides favorable reaction and aeration and enhancesthe longevity of these bacteria. Ogawa (1994) also found increased abundance of nitrogen fixing bacteria insoil amended with biochar. Rondon et al. (2007) found increased biological nitrogen fixation by common beansthrough biochar additions and Gehring (2003) increased occurrence of nitrogen-fixing nodules in plants in forestson Terra Preta compared to adjacent soils. Also the colonization rates by mycorrhizal fungi was enhancedin the majority of experiments conducted (Warnock et al. 2007). The effects on soil biology seem to be essentialas biochar has the potential to alter the microbial biomass (Steiner, Das et al. 2008; Steiner et al. 2004) and composition(Birk 2005) and the microbes are able to change the biochar’s properties (Glaser et al. 2001). Increasedmicrobial biomass was also found in temperate soils in the U.S. after biochar application (Kolb, Fermanich, andDornbush 2008). Wardle, Zackrisson, and Nilsson (1998) found that biochar stimulated active soil microbial biomassand the presence of biochar increased nitrogen uptake in a boreal forest ecosystem and concluded thatbiochar provides a major contribution to the rejuvenating effects of wildfire on forest ecosystems.Decreased acidity, exchangeable aluminum and increased mineral nutrition on acidic tropical soils was foundby Steiner et al. (2007; Topoliantz, Ponge, and Ballof (2005); and Major et al. (2010). But also mineral nitrogenfertilization was more efficient on soils containing biochar. Lehmann et al. (2003) found significantly reducedleaching of applied fertilizer nitrogen in biochar containing pots. This was corroborated in a field experiment bySteiner, Glaser et al. (2008). The recalcitrant nature of biochar makes it rather unlikely that nitrogen immobilizationcaused this increased nitrogen retention. Terra Preta soils show not only a doubling in the organic carboncontent but also a higher cation exchange capacity (CEC) than would be expected from the sum of the colloidalactivity of the organic matter and the kaolinitic clay minerals individually (Sombroek, Nachtergaele, and Hebel1993). In Terra Preta soils it appears the oxidation of the biochar that creates carboxylic groups on the edges ofthe aromatic core, which are responsible for the increased CEC and reactivity of biochar in the soil (Glaser et al.2001). The high specific surface area, oxidation of the biochar itself and adsorption of organic matter to biocharsurfaces may contribute to the high CEC found in soils containing biochar (Liang et al. 2006). This raises hopethat the beneficial effects of charcoal amendments increase over time. Increased fertilizer use efficiency was alsofound in Australia (Chan et al. 2007) and the UK (Gathorne-Hardy, Knight, and Woods 2009). Similar to the studiedtropical soils agricultural soils in the southeastern U.S. Coastal Plain have meager soil fertility characteristicsbecause of their sandy textures, acidic pH values, kaolinitic clays, low cation exchange capacities, and diminutiveSOC contents. Biochar additions to such soils significantly reduced acidity and improved soil fertility (Novak,Busscher et al. 2009; Novak, Lima et al. 2009). Laird et al. (2010) assessed the impact of biochar amendmentson the quality of a typical Midwestern agricultural soil. This soil is not considered meager; however the authorsreport significantly increased CEC, and extractable plant nutrients. The supply of nutrients largely depends onthe feedstock used for biochar production. Depending on pyrolysis temperature, most nutrients (with excep-4U.S.-Focused Biochar Report:Assessment of Biochar’s Benefits for the United States of America