1. a Chemistry Department , Soil Resource Development Institute , Kampsax International A/S, Dhaka , 1215 , Bangladesh
2. b Chemistry Department , The Royal Veterinary and Agricultural University , 40 Thorvaldsensvej, DK-1871 , Frederikberg C , Denmark
3. c Department of Agricultural Sciences , The Royal Veterinary and Agricultural University , 40 Thorvaldsensvej, DK-1871 , Frederikberg C , Denmark
4. d Soil Resource Development Institute , Kampsax International A/S, Dhaka , 1215 , Bangladesh