1. Institut National de la Recherche Agronomique (Inra), UR0272, Science du Sol, Centre de Recherche Val de Loire; CS 40001 F-45075 Orléans Cedex 2 France
2. College of Resources and Environment, State Key Laboratory of Soil Erosion and Drying Farming on the Loess Plateau; Northwest A & F University; Yangling Shaanxi 712100 PR China
3. Institute of Soil and Water Conservation (CAS); No. 26 Xinong Road 712100 Yangling Shaanxi China
4. INRA, UMR LISAH (INRA-IRD-SupAgro); 2 Place Pierre Viala F-34060 Montpellier France