1. Institute of Soil Science and Soil Conservation, Research Centre for BioSystems, Land Use and Nutrition (iFZ), Justus Liebig University Giessen, Heinrich-Buff-Ring 26, 35392 Giessen, Germany
2. SARChI Chair for Mine Water Management, Tshwane University of Technology (TUT), Private Bag X680, Pretoria 0001, South Africa