Saturday, 27 March 2010

Effect of biochar and biodigester effluent on growth of maize in acid soils

The paper linked above shows some amazing results for the application of biochar on tropical soils in Columbia. Lets hope these sort of results can be replicated in SEA soil trials...


  • Biochar produced as a byproduct of the gasification of sun-dried, sugar cane bagasse (the cane stalks were passed two times through a 3-roll mill traditionally employed for making “panela”), contained 35% ash.
  • Application of the biochar (50 g/kg of soil) to a fertile soil (from a shaded coffee plantation) increased above ground biomass growth five-fold with no additional benefit from simultaneous application of biodigester effluent. When applied to a sub-soil, there was a synergistic effect of the biochar and the biodigester effluent; the biochar alone increased yield eight-fold but combined with biodigester effluent the increase was twenty-fold. Effects on the root biomass were similar.
  • The initial pH of both soils was in the range of 4.0-4.5 and was increased to 6.0-6.5 by addition of the biochar. Effluent application did not affect soil pH.
  • Application of ash from a wood-burning stove at 50g/kg soil also increased maize yield but to a level of only one third of that achieved with biochar. The increase in soil pH was double that observed with biochar reaching levels of between 9 and 10"

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