995 Research Article Received: 17 April 2012 Accepted article published: 3 September 2012 Published online in Wiley Online Library: 15 October 2012 (wileyonlinelibrary.com) DOI 10.1002/jsfa.5889 Differential growth and yield by canola (Brassica napus L.) and wheat (Triticum aestivum L.) arising from alterations in chemical properties of sandy soils due to additions of fly ash Isa A M Yunusa, a,g* Veeragathipillai Manoharan, a,g Rob Harris, b Roy Lawrie, c Yash Pal, d Jonathan T Quiton, e Richard Bell f and Derek Eamus a Abstract BACKGROUND: There is a need for field trials on testing agronomic potential of coal fly ash to engender routine use of this technology. Two field trials were undertaken with alkaline and acidic fly ashes supplied at between 3 and 6 Mg ha -1 to acidic soils and sown to wheat and canola at Richmond (Eastern Australia) and to wheat only at Merredin (Western Australia). RESULTS: Ash addition marginally (P< 0.10) raised the pH in the top soil layers at both sites. The exceptionally dry season at both sites constrained yields and thwarted any likelihood of gaining yield benefits from ash-induced improvements in soil conditions. Yield improvements due to ash addition were absent at Merredin and only marginal at Richmond, where no elevated accumulation of B, Mo, Se, P or S in either the straw or seeds of wheat was observed; canola increased accumulation of Mo and Se in its shoot with acidic fly ash, but it was well below phyto toxic levels. Simulations of wheat using APSIM at Richmond over a 100-year period (1909 – 2008) predicted yield increases in 52% of years with addition of ash at 3.0 Mg ha -1 compared with 24% of years with addition of ash at 6.0 Mg ha -1 . The simulated yield increases did not exceed 40% over the control with addition of 6 Mg ha -1 ash, but was between 40% and 50% with an addition rate of 3 Mg ha -1 . CONCLUSION: We found no evidence of phytotoxicity in either crop in this unusually dry year and there is still a need for further field assessment in years with favourable rainfall to enable development of clear recommendations on fly ash rates for optimum yield benefits. c  2012 Society of Chemical Industry Keywords: APSIM; boron; canola; drought; molybdenum; phosphorus; selenium; soil acidity; sulfur; wheat INTRODUCTION Increasing costs and declining reserves of major sources of fertilizers and soil amendments demand a search for substitutes, and the potential for industrial by-products to fulfil this role cannot be ignored. Coal fly ash is such a by-product that is produced in large amounts, but mostly disposed of through land emplacement. This is despite its potential as an ameliorant of adverse soil chemical conditions and a source of key plant nutrients. Indeed, there is much empirical evidence for beneficial use of the ash in ameliorating a range of physical and nutritional deficiencies in soil that constrain crop growth and yield, including acidity, 1,2 sodicity 3 and poor nutrient availability. 4,5 There have, however, also been reported instances of reduced growth and yield in crops supplied with fly ash. This usually occurs with high rates of ash addition resulting in excessive amounts of the trace elements in soil that then become phytotoxic to the plant. 6 Trace elements commonly identified as phytotoxic when in excessive concentration include B, Cu, Mo, Se and Zn. 2,7 – 9 For ∗ Correspondence to: Isa A M Yunusa, School of Environmental and Rural Sciences, University of New England, Armidale, NSW. 2351 Australia. E-mail: iyunusa@une.edu.au a Plant Functional Biology & Climate Change Cluster, University of Technology, Sydney, NSW, 2007, Australia b Department of Primary Industries, Rutherglen, Vic, 3685, Australia c Department of Primary Industries, Richmond, NSW, 2753, Australia d Department of Environment and Conservation, Western Australia, Bentley, WA 6983, Australia e Department of Mathematics, University of Western Kentucky, Bowling Green, KY, 42101, USA f School of Environmental Science, Murdoch University, WA, 6150, Australia g School of Environmental and Rural Sciences, University of New England, Armidale, NSW, 2351, Australia J Sci Food Agric 2013; 93: 995–1002 www.soci.org c  2012 Society of Chemical Industry