Location: Soil and Water Management ResearchTitle: Biochar: The field experience Author
Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 3/10/2013
Publication Date: 1/5/2015
Citation: Spokas, K.A., Novak, J.M. 2015. Biochar: The field experience. In: Goreau, T.J., Larson, R.W., Campe, J., editors. Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase. Boca Raton, FL: CRC Press. p. 235-248.
Technical Abstract: Despite the relatively new concept of biochar, which is utilizing chemical-thermal alterations of biomass to achieve carbon sequestration, the purposeful addition of biochar-like materials to soils can be traced back to the beginning of our modern science record. In addition, there is anthropological evidence of biomass pyrolysis residues and products being used in earlier civilizations. The process of pyrolysis converts the biomass into a carbon form that is more resistant to degradation than the parent biomass. Even though the amendment was not called biochar, we have been utilizing the solid residue from biomass pyrolysis for at least the 300 years of our modern science record as a soil fertilizer agent. The use of charcoal amendments in the past has been limited by the economics, which hampered scientific investigations into the mechanisms of charcoal’s improvement in soils. Despite this, there were reports at this time of charcoal improving soil physical properties, water holding capacity, and the action of other fertilizers after application. In the 1900’s, new scientific developments expanded the potential uses of charcoal, thereby removing some of the emphasis on agricultural use. However, charcoal continued to be investigated as a filtration media and uses in non-target agrochemical protection. Now in the early 2000’s, biochar has entered the public’s vocabulary, as seen in the Google™ Trends graph (Figure 1). Currently, the emphasis is on biochar production temperatures as a description, but past research also has demonstrated that the rates of heating and cooling can be more important than the maximum pyrolysis temperature reached. These factors stress the importance of fully documenting the source of biochar, so that future efforts will not be hindered by the lack of adequate characterization data. Even though we have been using charred amendments for a long time, there is a significant amount of hype, skepticism, and uncertainty surrounding how soil biochar additions have performed historically and what guidance this provides for the future. This chapter will synthesize what we know from looking back at the past and current field experiments investigating biochar additions.