A greenhouse study was conducted to begin testing the use of coal char (CC) as a soil amendment where CC is a solid porous activated carbon material resulting from a high-temperature pyrolysis of coal. The objectives of this preliminary trial were to evaluate the impacts of different concentrations of CC added to the soil (0% (control), 1%, 5%, and 10% (v/v) on plant biomass yield and soil water holding capacity (WHC). The study was designed with ten replications using alfalfa as the test plant in two different soils: an uncultivated rangeland soil and cultivated agricultural soil. The application of 5% CC leads to a significant increase (p < 0.05) in alfalfa mean dry biomass production of 1.54 ± 0.31g in Agricultural soil and 1.85 ± 0.25 g in rangeland soil compared to 1.05 ± 0.22g and 1.20 ± 0.27g mean biomass production in controls of the respective soils. The growth of alfalfa plants was not significantly affected, positively or negatively, in any other treatments. A significant increase (p < 0.05) in soil WHC was observed at 5 and 10% CC concentrations in both soils in comparison to their respective controls. Therefore, adding coal char at optimal rates may increase plant growth and soil WHC in dryland soils.

Keywords: Coal char, plant growth, soil water holding capacity, soil amendment, alfalfa