PERTANIKA JOURNAL OF TROPICAL AGRICULTURAL SCIENCE

Basic research conducted on humic acid (HA) in tropical soils is limited. A study was conducted to characterize HA extracted from tropical peat by elemental and functional group analyses, infrared (IR) spectra and by direct examination on HA using scanning electron microscopy (S E M) . From the elemental analysis it was found that C ranged from 40.26 - 53.26%, H 4.84 - 6.36%, 0 38.39 - 51.62%, JV 1.51 - 2.64%, and P 0.02 - 0.06%. Studies of functional groups indicated that the carboxyl group present in HA o f tropical peat was about twice as high as that of phenolic hydroxyl groups. From IR spectra, the HA had an aromatic character. Results o f IR analysis also exhibited consistently similar spectra, demonstrating that regardless o f place o f origin, the extracted humic compound had a similar structure and was composed o f the same functional groups. Electron microscopic examination o f dried HA showed a sub-angular blocky shape which varied in size. All extracted HA exhibited similar form.