1. Crop Production Department; ESALQ/USP; C.P. 9 13418-970 Piracicaba SP Brazil
2. Soil Science Department; Rothamsted Research; Harpenden Herts AL5 2JQ UK
3. Universiti Putra Malaysia; Department of Soil Science; 43400 Serdang Selangor Malaysia
4. Soil Physics Lab.; CENA/USP; C.P. 96 13416-000 Piracicaba SP Brazil
5. Institute of Agricultural Sciences of Southern Vietnam; Hochiminh City Vietnam
6. Joint FAO/IAEA; P.O. Box 100 A-100 Vienna Austria
7. Faculty des Sciences, Dep. des Biologie; Univ. Moulay Ismail; B.P. 4010, Beni M'Hamed Meknes Morocco
8. Soil Science Division; Bangladesh Institute of Nuclear Agriculture; P.O. Box 4 Mymensigh 2200 Bangladesh
9. Dep. of Agricultural Microbiology, Faculty of Agriculture; Minia Univ.; El-Minia Egypt
10. Department of Crop Science, Faculty of Agriculture; Univ. of Peradeniya; Peradeniya Sri Lanka
11. Rural Engineering Department; UFPel; C.P.354 96001-970 Capao do Leao RS Brazil
12. Institute of Environmental Resources and Soil Fertilizer, Zhejiang Academy of Agricultural Sciences; People's Republic of China
13. Facultad de Agronomia, Department de Suelos; Universidad de Concepcion; Chillan Chile
14. Dep. of Plant Sciences; Univ. of California; Davis CA 95616