1. State Key Lab. of Soil and Sustainable Agric.; Institute of Soil Science Chinese Academy of Sciences; Nanjing People's Republic of China
2. College of Resource and Environ. Sci. Nanjing Agriculture Univ.; Nanjing People's Republic of China
3. Dep. of Environmental Sciences; Univ. of California-Riverside; Riverside CA
4. Institute of Water Resources Research Xi'an Univ. of Technology; Xi'an Shannxi People's Republic of China