Algal biochar enhances the re-vegetation of stockpiled mine soils with native grass

Roberts, David A., Cole, Andrew J., Paul, Nicholas A., and De Nys, Rocky (2015) Algal biochar enhances the re-vegetation of stockpiled mine soils with native grass. Journal of Environmental Management, 161. pp. 173-180.

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In most countries the mining industry is required to rehabilitate disturbed land with native vegetation. A typical approach is to stockpile soils during mining and then use this soil to recreate landforms after mining. Soil that has been stockpiled for an extended period typically contains little or no organic matter and nutrient, making soil rehabilitation a slow and difficult process. Here, we take freshwater macroalgae (Oedogonium) cultivated in waste water at a coal-fired power station and use it as a feedstock for the production of biochar, then use this biochar to enhance the rehabilitation of two types of stockpiled soil – a ferrosol and a sodosol – from the adjacent coal mine. While the biomass had relatively high concentrations of some metals, due to its cultivation in waste water, the resulting biochar did not leach metals into the pore water of soil-biochar mixtures. The biochar did, however, contribute essential trace elements (particularly K) to soil pore water. The biochar had very strong positive effects on the establishment and growth of a native plant (Kangaroo grass, Themeda australis) in both of the soils. The addition of the algal biochar to both soils at 10 t ha^−1 reduced the time to germination by the grass and increased the growth and production of plant biomass. Somewhat surprisingly, there was no beneficial effect of a higher application rate (25 t ha^−1) of the biochar in the ferrosol, which highlights the importance of matching biochar application rates to the requirements of different types of soil. Nevertheless, we demonstrate that algal biochar can be produced from biomass cultivated in waste water and used at low application rates to improve the rehabilitation of a variety of soils typical of coal mines. This novel process links biomass production in waste water to end use of the biomass in land rehabilitation, simultaneously addressing two environmental issues associated with coal-mining and processing.

Item ID: 39417
Item Type: Article (Research - C1)
ISSN: 1095-8630
Keywords: biochar; macroalgae; mine rehabilitation; terrestrial restoration; mining; metals
Funders: Advanced Manufacturing Cooperative Research Centre (AMCRC), Australian Renewable Energy Agency (ARENA)
Projects and Grants: MBD Energy Research and Development program for Biological Carbon Capture and Storage
Date Deposited: 14 Jul 2015 00:42
FoR Codes: 10 TECHNOLOGY > 1002 Environmental Biotechnology > 100203 Bioremediation @ 20%
05 ENVIRONMENTAL SCIENCES > 0502 Environmental Science and Management > 050207 Environmental Rehabilitation (excl Bioremediation) @ 40%
07 AGRICULTURAL AND VETERINARY SCIENCES > 0703 Crop and Pasture Production > 070399 Crop and Pasture Production not elsewhere classified @ 40%
SEO Codes: 96 ENVIRONMENT > 9609 Land and Water Management > 960908 Mining Land and Water Management @ 20%
96 ENVIRONMENT > 9612 Rehabilitation of Degraded Environments > 961205 Rehabilitation of Degraded Mining Environments @ 40%
96 ENVIRONMENT > 9614 Soils > 961404 Mining Soils @ 40%
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