Effects of oil palm bunch refuse on humic acid content of five soils grown to oil palm.

Abstract

The effect of the addition of composted oil palm bunch refuse on five different soils supporting palms with respect to the acidic functional groups of the humic acids in the soils was investigated. The composts was added to the soils at different rates. The results showed that there was a highly significant (P =0.001) increase in the carboxylic (-C00H) groups as compared with the phenolic -OH groups. Total acidity also increased with the E4/E6 ratio of the isolated humic acids. These changes were associated with the different types of soil and rates of applied composts. Carboxylic (-C00H) groups contributed more to total acidity of the humic acids. The study revealed that addition of composted oil palm bunch refuse to soil is a potential source of carboxylic (-C00H) groups in the humic acid fraction of the soil.


Keywords: Oil palm bunch, humic acids, carboxylic groups, phenolic groups, E4/E6 ratio.

[Global Jnl Agric Res Vol.2(1) 2003: 43-52]