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Experimenting with modified extruded seed pellets for large scale mine rehabilitation

Stock, Emma (2019) Experimenting with modified extruded seed pellets for large scale mine rehabilitation. Masters by Coursework thesis, Murdoch University.

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Current methods of mine rehabilitation have a high failure rate at the seedling emergence stage due to the limited availability of topsoil and the low water holding capacity of alternative growth media such as waste materials and tailings. Extruded seed pellets, formed by extruding soil mixtures and seeds into pellets, can potentially increase soil water availability through enhanced soil-seed contact and improve seedling emergence in arid systems. I tested a modified extruded seed pelleting method in a three-factor field experiment in a purpose-built mine rehabilitation research facility in the Pilbara region of northwest Western Australia. The aims of the experiment were to assess (i) native seedling emergence and establishment from modified extruded seed pellets and; ii) the physico-chemical and microbiological changes that occur with seedling emergence from pellets. I tested three native plant species and the experimental factors were pellet soil mixtures, with or without Triodia pungens biomass as an organic amendment and rainfall regimes. Results suggests trade-offs among responses. Pellets made with a 50:50 blend of topsoil and waste material had the highest seedling emergence, while 100 % topsoil pellets had lower emergence probably because of hardsetting. Triodia pungens survived to the end of the experiment but Indigofera monophylla and Acacia inaequilatera did not. Adding Triodia biomass amendment inhibited Triodia seedling emergence but increased soil microbial activity and could therefore stimulate recovery of soil function. Pellets preserved seed viability and topsoil microbial communities during the growing season and therefore show potential as a means to inoculate rehabilitation sites with both seeds and microbes. Overall, modified extruded 50:50 seed pellets show promise for rehabilitation of keystone species Triodia and beneficially, make use of ‘waste’ material. Further research is needed to improve pelleting methodology for other species, and to test the applicability of the method at scale, in this and other arid land ecosystems.

Item Type: Thesis (Masters by Coursework)
Murdoch Affiliation(s): Environmental and Conservation Sciences
United Nations SDGs: Goal 12: Responsible Consumption and Production
Supervisor(s): Standish, Rachel, Erickson, Todd, Muñoz-Rojas, Miriam and Bell, Richard
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