1. Dept. of Soil Science & Soil Ecology, Geographical Institute, Ruhr‐University Bochum, Universitätsstr. 150, 44780 Bochum, Germany
2. Institute of Crop Science and Resource Conservation, Dept. Soil Science and Soil Ecology, University of Bonn, Nussallee 13, 53115 Bonn, Germany
3. Leibniz‐Laboratory for Radiometric Dating and Stable Isotope Research Kiel, University of Kiel, Max‐Eyth‐Str. 11–13, 24118 Kiel, Germany
4. Max‐Planck‐Institute for Biogeochemistry, P.O. Box 100164, 07701 Jena, Germany
5. present address: Institute of Soil Science and Site Ecology, Dresden University of Technology, Pienner Str. 19, 01737 Tharandt, Germany
6. Department of Geography, Soil Science & Biogeography, University of Zurich, Winterthurerstr. 190, 8057 Zurich, Switzerland
7. Institute for Land Use, University Rostock, Justus‐von‐Liebig‐Weg 6, 18059 Rostock, Germany
8. Institute for Environmental Research, RWTH Aachen, Worringerweg 1, 52074 Aachen, Germany
9. present address: State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, 210093 Nanjing, China
10. Dept. Soil Science, Martin‐Luther University Halle‐Wittenberg, Weidenplan 14, 06108 Halle (Saale), Germany
11. Dept. of Soil Ecology, University of Bayreuth, 95440 Bayreuth, Germany
12. Dept. of Analytical Chemistry and Reference Materials, Federal Institute for Materials Research and Testing, Richard‐Willstaetter‐Straße 11, 12489 Berlin, Germany
13. Fachbereich Geowissenschaften, Universität Bremen, P.O. Box 330 440, 28334 Bremen, Germany
14. Dept. for Geology and Mineralogy, University of Cologne, Zülpicher Str. 49a, 50674 Cologne, Germany
15. present address: Agroecosystem Research, University Bayreuth, 95440 Bayreuth, Germany