Improving the Recovery of Constructed Mine Soil Profile with Flue Gas Desulfurization Gypsum

Flue gas desulfurization gypsum (FGDG) is a by-product generated in the combustion of coal. This solid residue has the potential to be applied to the soil and help to reduce acidity and provide nutrients to soils impacted by surface coal mining. Thus, the objective of this work was to evaluate nutrients and heavy metals in soil and plant tissue and the development of ryegrass in two soils impacted by coal mining under FGDG application. Thus, an experiment was conducted under controlled conditions with two materials used for the construction of the recovered soil profile after mining, topsoil and overburden, after 10 years of coal mining in southern Brazil. The treatments consisted of control treatments and application of FGDG at a dose considered to correct soil acidity in the constructed mine soil materials under ryegrass ( Lolium multiflorum ) cultivation. It was observed that the application of FGDG increased the availability of potassium (+ 25%) and calcium (+ 38%) in the topsoil. In the overburden, FGDG increased the availability of phosphorus (+ 33%), calcium (+ 25%) and Mg (+ 31%). The FGDG was important in reducing the active and potential acidity of the soil, increasing the dry matter of ryegrass plants cultivated in the overburden (+ 31%). Thus, the use of FGDG contributes to reduce soil acidity, increasing nutrient availability and ryegrass development without increasing the levels of heavy metals in the soil and in the plant tissue, indicating that its application in the constructed mine soil constitutes a suitable alternative of use of this residue.