1. Key Lab. of Agricultural Soil and Water Engineering in Arid and Semiarid Areas Ministry of Education Northwest A&F Univ.; Yangling Shaanxi 712100 P.R. China
2. College of Water Resources and Architectural Engineering Northwest A&F Univ.; Yangling Shaanxi 712100 P.R. China
3. Institute of Water-saving Agriculture in Arid Areas of China (IWSA) Northwest A&F Univ.; Yangling Shaanxi 712100 P.R. China