Germination and early growth of crop and pasture species on media amended with two contrasting types of coal fly-ashes

In order to identify rapidly which plant species could potentially benefits from application of fly ash, we used 'the OECD Terrestrial Plant Growth Test' (Guideline 208) toxicology test to assess performance of selected monocots (barley and ryegrass) and dicots (canola, peas, radish) on media treated with ash. The ashes were obtained from power stations burning either lignite (red ash) or semi-bituminous (grey ash) coal, and applied to grow media at rates equivalent to between 0 and 20 Mg/ha. Germination, pigment concentration and dry weight were measured in the first 4 weeks after germination. Germination was not affected by either fly-ash. Neither of the 2 monocots showed any positive response to the red ash, but barley increased its dry weight with the grey ash at all rates. Except canola with red ash, the dicots increased their weights with either fly ash applied at rates of up to 10 Mg/ha, but beyond this rate there was mostly a decline in weight. While photosynthetic pigments in the monocots were not affected, those of the dicots were increased, by the ashes. Most of the adverse effects of the red ash on plant growth could be associated with its high salinity and boron content.