SUMMARY

Various efforts have been made to improve the soil characteristics of tropical peatland, for example, the addition of ash or chemical and physical treatments. It is expected that by increasing the pH the availability of nutrients for food crops cultivation in tropical peatland will also increase. A series of experiments was conducted to increase the pH of peat soil through a microbiological approach in an original peatland near Pontianak, West Kalimantan, Indonesia where the pH was 3.5-3.6. Oil palm empty fruit bunches, mesocarp fibre and palm kernel cake from the palm oil industry were used as carbon sources for microbial fermentation and these were layered on the peat surface and inoculated with a designed microbial consortium. The layers were mixed thoroughly with 10-15 cm of the surface peat and then covered with plastic sheet. The soil characteristics and pH were analyzed weekly for 6 weeks. The microbes metabolized the substrate and peat soil resulting in a significantly increased pH and base saturation. After 6 weeks incubation, the microbial consortium with oil palm empty fruit bunches as carbon source was the best treatment, resulting in a final pH of 5.5. It was also shown that the cation exchange capacity (CEC) tended to decrease during incubation, while C/N ratios varied between treatments. The possible mechanisms involved in the microbial treatment on pH increment in peatland are discussed