Biochar: for better or for worse?

Freddo, Alessia (2013) Biochar: for better or for worse? Doctoral thesis, University of East Anglia.

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Abstract

This thesis presents biochar state of the art and investigations into the environmental benefits
and potential impacts of biochar application to soil.
Specifically, the opportunity biochar has to increase concentrations of potentially toxic
elements (PTE) and polycyclic aromatic hydrocarbons (PAHs) in soil was investigated and
contextualised. Results indicated limited environmental impacts in this regard.
The capacity of biochar to interact with organic compounds was studied in two contexts:
PAHs absorption and partitioning; and with respect to bioavailability and potential
deactivation of herbicides.
Regarding PAH partitioning, sewage sludge biochar (SSBC) was established to be more
efficient than sewage sludge (SS) in reducing the bioaccumulation of PAHs in Lactuca
satuva L. grown in contaminated soil; while increasing significantly (p < 0.05) biomass yield,
relatively to a soil only control.
Regarding herbicides, biochar amended soil was observed to reduce herbicide extractability
(< 2%). This extractability being far lower than that observed in the biochar free control soils
(40% and 90%). 14C-radiorespirometry indicated that herbicide sequestration within biochar
greatly reduced its bioavailability.
Biochar influence upon weed survival indicated high biochar application rates (5%) to reduce
the effectiveness of herbicides, suggesting that biochar incorporation in to soil at these levels
could potentially undermine agriculture that relies upon herbicides.
Finally, biochar was tested as microbial carrier. Rhizobacteria survival was established to be
higher in biochar produced from redwood than in peat (a common microbial carrier) at high
incubation temperatures (25°C and 35°C).
In conclusion, biochar addition to soil presents limited direct environmental pollution impact.
While biochar absorptivity may be beneficial in mitigating the bioavailability of organic
contaminants this trait needs to be considered carefully in agricultural soils where herbicides
are relied upon. Given the encouraging results regarding the potential for biochar to act as a
microbial inoculant carrier, further research is warranted.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Science > School of Environmental Sciences
Depositing User: Mia Reeves
Date Deposited: 12 Mar 2014 14:58
Last Modified: 12 Mar 2014 14:58
URI: https://ueaeprints.uea.ac.uk/id/eprint/48115
DOI:

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