1. State Key Laboratory of Soil and Sustainable Agriculture; Institute of Soil Science; Chinese Academy of Sciences; Nanjing 210008 China
2. Institute of Plant Nutrition and Soil Science; Christian-Albrecht University Kiel; Kiel 24118 Germany
3. Institute of Applied Plant Nutrition; Georg-August University Goettingen; Goettingen 37075 Germany
4. Institute for Plant Production and Agroecology in the Tropics and Subtropics; University of Hohenheim; Stuttgart 70593 Germany
5. Institute of Physicochemical and Biological Problems in Soil Science; Russian Academy of Sciences; Institutskaya 2 Pushchino 142290 Russia
6. Institute of General and Inorganic Chemistry; Tashkent 100170 Uzbekistan
7. Department of Soil Science of Temperate Ecosystems; Georg-August University of Göttingen; Göttingen 37077 Germany
8. Department of Agricultural Soil Science; Georg-August University of Göttingen; Göttingen 37077 Germany