Fly ash generated from coal-fired power plants is a potential source of pollutant, but can be used as a soil ameliorant to increase plant biomass and yield in agriculture. However, the effects of fly ash application to soil on plant biomass and the element accumulations in plants remain unclear. Based on 88 articles, we conducted a comprehensive meta-analysis to evaluate plant biomass and concentrations of 21 elements in plants in response to fly ash application. These elements included macro-nutrients (N, P, K, Ca, and S), micro-nutrients (B, Co, Cu, Fe, Mn, Mo, Ni, and Zn), and heavy metals (Al, As, Cd, Cr, Pb, and Se).
Results/Conclusions
Overall, fly ash application decreased plant biomass by 15.2%. However, plant biomass was enhance by fly ash application by 11.6~29.2%% at lower application rate (i.e. <25% of soil mass), and decreased by 45.8% at higher application rate (i.e. 50-100%). Belowground biomass was significantly reduced while yield was enhanced by fly ash application. Most of the element concentrations in plants were enhanced by fly ash application, and following an descending order as heavy metals > micro-nutrients (B, Cu, Fe, Mn, Mo, Ni, and Zn) > macro-nutrients (P, K, Ca, and S). Concentrations of elements tended to increase with an increase in fly ash application rate. Our syntheses indicated that fly ash should be applied at less than 25% in order to enhance plant biomass and yield, and cause less accumulations of heavy metals in plants.