1. State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau; Institute of Soil and Water Conservation; Northwest A&F University; Yangling Shaanxi 712100 China
2. Institute of Soil and Water Conservation; Chinese Academy of Sciences and Ministry of Water Resources; Yangling Shaanxi 712100 China
3. Faculty of Agriculture; Tottori University; Koyama Minami 4-101 Tottori 680-8533 Japan
4. NARO Agricultural Research Center; Kannondai 3-1-1 Tsukuba 305-8666 Japan