The current study was undertaken to evaluate the success of a revegetation program on three sites within the Bauxite Residue Disposal Area at the Aughinish Alumina Ltd. refinery. This was achieved by determining botanical diversity, substrate conditions, and plant uptake. Two sites revegetated in 1999, with and without the use of gypsum, were assessed and compared to a site revegetated in 1997. Compared to an initial 6 species used in seeding, a total of 47 species were recorded growing on the three sites with greatest diversity on the 1997 site. There was limited variation in the residue properties of the three treatments indicating that diversity was most influenced by succession and not substrate conditions. Limited available manganese was found in all treatments and significantly lower exchangeable magnesium in the gypsum-amended treatment. Exchangeable sodium, aluminum, and pH in the substrate were not at levels of concern. Appreciable nitrogen, phosphorus, and potassium were found as a result of a fertilizing program. Dominant species in the 1999 treatments, Holcus lanatus and Trifolium pratense, were analyzed for elemental composition. Compared to previous studies, foliar nitrogen, phosphorus, potassium, and calcium were adequate and sodium levels were low. Manganese and magnesium levels were low, and availability should be assessed as part of the monitoring program. Furthermore, the effect of a fertilizing regime on plant uptake and substrate conditions needs to be assessed.

Physical properties exhibited by unvegetated mine wastes pose limitations to vegetation establishment and growth. In an attempt to promote vegetation cover on bauxite residue, a field trial was established to determine the effect of spent mushroom compost (SMC) and gypsum amendment on enhancing the physical properties of the residue. SMC was incorporated at rates of 0, 60, 80 and 120 t ha À1 with gypsum at 0, 40 and 90 t ha À1 and Holcus lanatus sown at a rate of 80 kg ha À1 . The addition of SMC and gypsum was beneficial in improving the physical properties of the residue and promoting growth. Principally increasing organic content of the residue decreased bulk density and particle density whilst improving substrate porosity. Residue pH, EC and sodicity of the residue were also affected by the amendments, which positively impacted on microaggregate stability and preventing clay dispersion. Pearson correlations demonstrate that the most significant parameters in determining clay dispersion potential are the pH and the exchangeable sodium percentage (ESP) of the residue.

Bauxite residues are very slow to naturally vegetate due to nutrient deficiency and high sodicity. In order to test the effectiveness of amendments at promoting revegetation, bauxite residue was amended with varying rates of compost to increase fertility (0, 60, 80 and 120 t ha−1) and gypsum to reduce sodicity (0, 40 and 90 t ha−1). Amended residue was sown with Holcus lanatus, a perennial grass. Following a 1‐year growth period, substrate properties, plant performance and plant nutrient uptake were assessed. Compost application substantially increased substrate N, P, K and Mn concentrations, while gypsum application greatly reduced sodicity and improved nutrient uptake for Mn and P. Compost amendment was essential for sustainable plant growth. Foliar deficiencies in N, P and Mg may persist with lower compost application rates, requiring the addition of supplemental fertiliser for healthy plant growth. Copyright © 2010 John Wiley & Sons, Ltd.

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