1. Earth Institute at Columbia University, 61 Route 9W, Palisades, NY 10964, USA.
2. Joint Research Centre, European Commission, 21020 Ispra, VA, Italy.
3. ISRIC–World Soil Information, 6700 AJ, Wageningen, Netherlands.
4. National Soil Survey Center, U.S. Department of Agriculture Natural Resources Conservation Service, Lincoln, NE 68508, USA.
5. Tropical Soil Biology and Fertility Institute of the International Center for Tropical Agriculture, Post Office Box 30677, Nairobi, Kenya.
6. Laboratoire d'Étude des Interactions Sols-Agrosystèmes-Hydrosystèmes, L'Institut National pour la Recherche Agronomique, Institut de Recherche pour Développement, SupAgro, 34060 Montpellier 1, France.
7. Faculty of Agriculture, Food and Natural Resources, The University of Sydney, Sydney, NSW 2006, Australia.
8. Commonwealth Scientific and Industrial Research Organization (CSIRO) Land and Water, Government Post Office Box 1666, Canberra, ACT, 2601, Australia.
9. EMBRAPA–Brazilian Agricultural Research Corporation, The National Center of Soil Research, Rua Jardim Botânico, 1024, 22.460-000, Rio de Janeiro, Brazil.
10. World Agroforestry Centre, Post Office Box 30677–00100, Nairobi 00100, Kenya.
11. State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science of the Chinese Academy of Sciences, Nanjing, China.