Evaluation of native Australian grass species for tolerance to sodium sulphate salinity in bauxite processing residue sand
Petersen, X., Fey, M. and Bell, R.W. (2012) Evaluation of native Australian grass species for tolerance to sodium sulphate salinity in bauxite processing residue sand. In: Society for Ecological Restoration Australasia 2012 Conference, 27 - 30 November, Perth, Western Australia.
Introduced grasses are currently used as temporary vegetation cover on bauxite residue storage areas (RSA) to suppress dust and erosion. Native Australian grass species are ecologically preferable, but their tolerance to the alkaline, sodic, and saline soil conditions of bauxite residue is unknown. Twenty-seven native grass species were pre-screened for their requirement of gibberellic acid and smoke water to break seed dormancy, a common problem for establishment of these species. Thirteen species were then compared with two currently-used, introduced grass species for their ability to emerge in bauxite residue sand pre-treated with gypsum, washed, then amended with Na2 SO4 to produce salinity (ECe) ranging from 2 -12dS/m. Austrostipa scabra and Chloris truncata showed the greatest tolerance to salinity with no inhibition up to 10dS/m. Neurachne alopecuroidea displayed a moderate-high tolerance to salinity with a 20% decrease in emergence over the treatment range. Microlaena stipoides and Themeda triandra exhibited moderate inhibition and Bothriochloa bladhii, Brachyachne convergens and Enneapogon polyphyllus displayed low tolerance to salinity. No native species had emergence exceeding 50% and none exceeded the emergence of the introduced species, Lolium rigidum. This investigation highlights the need to test the germinability of seed and dormancy-breaking requirements prior to use. Austrostipa scabra, C. truncata and N. alopecuroidea show potential as early-stage rehabilitation species, while M. stipoides and Themeda triandra could be established when salinity has declined. Field performance, including productivity and competition of these grasses compared with introduced species, remains to be tested on bauxite RSA.
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|Murdoch Affiliation:||School of Environmental Science|
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