The use of coal combustion fly ash as a soil amendment in agricultural lands (with comments on its potential to improve food security and sequester carbon)

► Range of physico chemical properties of coal combustion fly ash. ► How fly ash can contribute in atmospheric carbon capture and storage in soils. ► How fly ash can improve agronomic properties of soil. ► Potential of fly ash as a source of soil improvement and carbon sequestration. ► Possibility of application of coal fly ash into Australian soils. The growing dependence on coal-fired electricity generation has resulted accumulation of massive quantities of coal combustion by products such as fly ash and bottom ash which are regarded as problematic solid wastes all over the world. Being used beneficially in very less quantities, each year large amount of fly ash is disposed to arable lands which lead to degradation and contamination of land and ground water. However fly ash is identified as a useful soil ameliorant with its properties pertinent to the enhancement of soil fertility and productivity. Fly ash has the potential to improve soil physical, chemical and biological properties and is a source of readily available plant macro and micro-nutrients. Especially for countries whose soils show inherent structural and nutritional limitations for cropping and that need expensive and intensive management, fly ash creates a possible solution to improve crop yields and enhance food security. At the same time the soil added fly ash can involve in terrestrial carbon sequestration by enhancing the microclimate of the soils to facilitate organic matter humification to yield stable forms of soil carbon. This paper reviews the studies of fly ash as a soil amendment in order to present a comprehensive view of the possibility of using fly ash in agricultural lands to improve soil productivity while harvesting possible carbon sequestration benefits. Some identified adverse effects of fly ash addition that can hinder the crop growth in amended soils especially in long term applications have limited its potential use in cultivable lands. However more research work on existing gaps in knowledge to be filled (especially regarding the appropriate application rate and possible environmental contamination) may help to derive the maximum advantages of fly ash in terms soil improvement and waste disposal. The paper, in particularly examines the potential use of this plentiful solid waste material on soil amendment in Australian agricultural soils.