The growth of Agropyron elongatum in an artificial soil mix from coal fly ash and sewage sludge

A greenhouse experiment was performed to evaluate the feasibility of using an artificial soil medium produced from alkaline coal fly ash and sewage sludge for the growth of Agropyron elongatum (tall wheat grass). Sludge was amended with ash at an application rate of 0, 5, 10, 35 and 50% (w/w). Each mixture was then mixed with a loamy soil at either 1:1 or 1:5 (v/v) and incubated under greenhouse conditions for 3 weeks prior to plant growth experiment. Addition of the ash-sludge mixture significantly improved the seedling emergence and dry weight yields of Agropyron. Pots with 10% ash-sludge mixture at 1:5 v/v soil mixing ratio had the highest yield, while those with 10 and 35% ash-sludge amendment at 1:1 v/v soil mixing ratio had lower dry weight yields but were still higher than that of the control with fertilizer treatment. No deficiency in N and P was noted for the ash-sludge-amended pots at both 1:1 and 1:5. Shoot tissue Ca, Mg and B concentrations increased while K, Fe, Mn and Zn decreased with an increase in ash amendment rate. The root tissue Fe, Mn, Cu and Zn contents were significantly higher than those of the shoot tissue. Hence, no excessive accumulation of heavy metals was noted owing to the ash-sludge amendment. The increased yield even at a high amendment rate of 35% ash-sludge mixture at 1:1 v/v soil mixing ratio indicates the potential use of the ash-sludge mixture as an artificial soil mix for agricultural use.