Increasing the Nutrient Content in a Mine Soil Through the Application of Technosol and Biochar and Grown with Brassica juncea L.

Mining is an anthropogenic activity that causes a profound environmental impact in many parts of the world, including soil degradation through physical, chemical and biological transformations. Mine soils are nutritionally deprived habitats characterized by unfertile soil with low pH values, a low cation exchange capacity (CEC), low nutrient availability, and poor organic matter. Today, techniques such as the use of technosols and biochar are starting to be used with the aim of recovering these soils. In this experiment we will compare the nutrient supply, increased pH, total carbon, total nitrogen (TN) and CEC of two treatments made of different amendments (technosol and biochar) on a mine soil. We will also determine the capacity of biochar to fix nutrients and enhance the positive effects of technosols in order to achieve the continuous growth of Brassica juncea L. The effects of the treatments were studied at three different depths over the 45-cm length of each cylinder. The study lasted a total of 11 months, using a settling pond from a depleted copper mine in Touro (Galicia, north-west Spain). The results of this experiment revealed that the treatments applied increased the pH, nutrient, total carbon, TN and CEC values. In turn, in the majority of the factors studied, the treatment combining the technosol and biochar was the most effective, with the B. juncea L. grown on this treatment having the highest biomass values.