1. Inst. of Soil Science; Chinese Academy of Sciences; Nanjing 210008 China
2. Dep. of Civil and Structural Engineering; The Hong Kong Polytechnic University; Kowloon Hong Kong
3. Dep. of Agronomy; Nanjing Agricultural University; Nanjing 210095 China
4. Dep. of Civil & Structural Engineering; The Hong Kong Polytechnic University; Kowloon Hong Kong