Enhancing Oil Palm Empty Fruit Bunch (EFB) Compost by Addition of Burnt Rice Husk as Carrier Material for Selected Nitrogen-Fixing Bacteria

The current interest in minimizing the use of inorganic fertilizers and the increasing demand for the combined action of beneficial microorganisms and agricultural wastes is considered to have a positive impact on soil, crop productivity and sustainable agriculture. The objective of this study was to prepare a series of combinations of empty fruit compost (EFBC) and burnt rice husk (BRH) as carrier materials for selected nitrogen-fixing bacteria, evaluate their suitability, and determine the ability of the inoculated EFBC-BRH carrier materials. Different ratios of EFBC and BRH were used to prepare the carrier materials for the selected N₂-fixing bacteria, namely strains Sb35 and Sb42 of Bacillus sp. Both coarse and fine EFBCs were used for the preparations. The suitability of the combinations of EFBC-BRH as a bacterial carrier was tested by inoculating the different ratios of organic material combinations with the N₂-fixing bacteria and incubating them at room temperature for eight weeks, after which the effects on the bacterial population, pH, moisture content, and contaminants were determined. The results showed that the fine-textured EFBC-BRH carriers’ formulation (T5 to T8) were better carriers compared to the formulation of coarse-textured EFBC-BRH carriers (T1 to T4). The inoculated carrier T6 (1 fine structured EFBC: 1 BRH) showed the best response with an increase in Sb35 and Sb42 populations of 7.34% and 7.47%, respectively. In conclusion, T6 as a carrier material for Sb35 and Sb42 is suitable to be developed as a biofertilizer.