Use of coal gasification coarse slag to amend the soil water, nutrient and salt of waste dump in the northwest arid region: feasibility and potential

The intrinsic mechanism and impact process of how coal gasification coarse slag (CGCS) amends the physicochemical properties of a specific soil based on its properties are not yet clear. The study explored the properties of CGCS that can be used for soil amendment by evaluating the properties of topsoil and CGCS. Different CGCS additions (0%, 5%, 10%, 15%, and 20 wt%) were used in soil column incubation-leaching-evaporation experiments to investigate soil water retention during leaching and evaporation, nutrients increment and retention during leaching, soil salinity control transport during evaporation. The intrinsic mechanism and impact of CGCS amelioration with soil were further analyzed. The CGCS amendment had no risk of soil environmental. It loosened the soil and optimized the soil pores, had no effect on the soil texture, but improved the soil gradation. The amendment promoted water infiltration, reduced evaporation, and increased water retention. Also increased the soil nutrients increment and retention, but could not amend soil organic matter, and had limited effect on soil alkaline nitrogen increment and soil available phosphorus retention. The amendment effect on saline-alkali was weak. CGCS content was positively correlated with water nutrient amendment, while salt was opposite. CGCS amended the soil physicochemical properties in the arid mine area of Northwest China. The amendment of soil physical structure, mainly pore adsorption, promoted chemical properties. To overcome the shortcomings in the amendment, targeted modification of CGCS to amend specific soil is crucial research for efficient utilization.