STUDY OF COMPOSITION AND PROPERTIES OF HUMIC ACID UNDER SUBTROPICAL EVERGREEN BROAD-LEAF FOREST IN THE YELLOW EARTH

The composition and property of humic acid in the yellow earth under subtropical evergreen broad-leaf forest and glassland vegetation have been studied and compared. First; the forest soil humic acid was fractionalized into a brown,green and yellow fraction with column chromatraphy by using cel louse powder or sephadex G-50, while humic acid of glassland vegetation has only two fractions: the brown fraction and a yellow fraction. Their chemical and physical properties are apparently different. The optical densities are measured from 200-700 nm. The green humic acid has a strong absorpation maximum at 615, 575,and 450 uni, However the brown humic acid are featureless with the optical densities decreasing as the wavelength increases, occasionally as indication of maximum can be discerned in the 220-260 nm.The infrared spetra of both are different too. The green humic acid was easy to be oxidized by-air to give the original green colored solution. Ultimate analysis provides the carbon of green humic acid more than brown humic acid and the hydrogen content less than brown humic acid.