Using forest mulch to improve mine rehabilitation outcomes in Australia’s first Indigenous-owned bauxite mine
A demonstration project in northern Australia concludes that mulching with forest residues in bauxite mine rehabilitation has a positive effect on soil health and plant growth.
25 May 2023
A demonstration project in northern Australia, led by Gulkula Mining (with technical support from the Sustainable Minerals Institute of the University of Queensland), with project support from ASI and financial support from ASI Member, Nespresso, concludes that mulching with forest residues in bauxite mine rehabilitation has a positive effect on soil health and plant growth. The addition of mulch improved soil quality and reduced weeds. Forest residues should be used as mulch to increase mine rehabilitation success instead of being burnt as waste.
Bauxite mining in Australia’s tropical regions often involves clearing and burning forests, stripping topsoils, and transporting them to other areas to begin the rehabilitation process. However, a new Indigenous-owned and -operated bauxite mine, the Gulkula Mine, located in East Arnhem Land, is salvaging timber products from the forest before mining, while mulching the remaining forest vegetation and adding this to the soil to support better mine rehabilitation. A recent study compared soils with and without mulch to a reference native forest to assess the impact of mulching on soil quality indicators. The findings revealed that mulching improved soil chemical and physical properties such as electrical conductivity, total carbon, total nitrogen, organic carbon, water-soluble organic carbon, cation exchange capacity, and bulk density. The study suggests that using mulch amendments can significantly improve mine rehabilitation soils and promote better rehabilitation outcomes.
Traditional bauxite mining methods in northern Australia deplete soil organic matter, plant nutrients, and soil microbial diversity, in addition it changes the soil structure, which inevitably impacts post-mining rehabilitation and ecosystem rehabilitation. However, the addition of unburnt forest mulch can help restore the ecological balance of mined areas, create aesthetic value, and promote long-term sustainability. The Gulkula Mine’s land-clearing procedure does not permit burning native forests but instead salvages high-value timber products and uses the remaining mulch to support progressive mine rehabilitation, creating a suitable growth medium complete with nutrient-cycling capabilities.
The study’s results will guide future rehabilitation efforts at the Gulkula Mine and potentially inform alternative and better land management practices within the mining industry.
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