Enhancing bauxite residue properties for plant growth: Gypsum and organic amendment effects on chemical properties of soil and leachate.

Here, we assess the effects of gypsum and local organic waste as amendments to non-weathered, filter-pressed bauxite residue (BR) to improve its properties and support plant growth. In addition, we monitored the leachate quality of the amended BR under progressive leaching that simulated precipitation conditions in Northern Brazil. Free-draining column tests consisting of BR amended with gypsum and organic waste, at 5% and 10% w/w, respectively, were leached for 8 weeks to assess the effects on the chemical composition of BR and the leachates.