1. Institute of Crop Science and Resource Conservation, Soil Science and Soil Ecology; University of Bonn; Bonn; Germany
2. Departamento de Agronomia; Universidad Nacional del Sur; Bahía Blanca; Argentina
3. Key Laboratory of Terrestrial Ecological Process, Institute of Applied Ecology; Chinese Academy of Sciences; Shenyang; China
4. Department of Crop and Soil Science; Oregon State University; Corvallis; Oregon; USA
5. Institute of Soil Science and Soil Geography; University of Bayreuth; Bayreuth; Germany
6. Faculty of Soil Science; Moscow State University; Moscow; Russia