Spectral Properties and Colloidal Rehaviour of the Humic Acids of the Soils under Oak (Quercus incana), Dfodar (Cedrus deodara) and Chik (Pinus roxburghii) of Mussoorie Himalayas (U.P.)

The humic substances of the Mussoorie Himalayan soils (U.P.) under different vegetation covers, Were characterised with the help of non-degradative spectrophotometric methods. The ratios of optical densities or absorbance at 465 mp. And 665 mp. In respect of dilute aqueous humic acids was used as the indicator of carbon in aromatic nuclei and in alphabetic side chains. It was noticed that the absorption of light increased with the increase in the degree of condensation of the aromatic rings in them and was depleted by a lower E₄/E₅ ratios and lesser absorptions. As Such it was found that the humic substances under Chir (Pinus roxhurghii) contain large proportion of aliphatic structure in them in comparison to Deodar (Cedrus deodara) and Oak (Quercus incana) were the humic substances were more condensed with aromatic rings. The later were also found to be hydrophobic in nature with lower coagulation threshold values as compared to former and as such were more akin for tbe favourable soil aggregation.