Physicochemical profile of microbial-assisted composting on empty fruit bunches of oil palm trees
2015
Lim, Li Yee | Bong, Cassendra Phun Chien | Chua, Lee Suan | Lee, Chew Tin
This study was carried out to investigate the physicochemical properties of compost from oil palm empty fruit bunches (EFB) inoculated with effective microorganisms (EM∙1™). The duration of microbial-assisted composting was shorter (∼7 days) than control samples (2 months) in a laboratory scale (2 kg) experiment. The temperature profile of EFB compost fluctuated between 26 and 52 °C without the presence of consistent thermophilic phase. The pH of compost changed from weak acidic (pH ∼5) to mild alkaline (pH ∼8) because of the formation of nitrogenous ions such as ammonium (NH₄ ⁺), nitrite (NO₂ ⁻), and nitrate (NO₃ ⁻) from organic substances during mineralization. The pH of the microbial-treated compost was less than 8.5 which is important to prevent the loss of nitrogen as ammonia gas in a strong alkaline condition. Similarly, carbon mineralization could be determined by measuring CO₂ emission. The microbial-treated compost could maintain longer period (∼13 days) of high CO₂ emission resulted from high microbial activity and reached the threshold value (120 mg CO₂-C kg⁻¹ day⁻¹) for compost maturity earlier (7 days). Microbial-treated compost slightly improved the content of minerals such as Mg, K, Ca, and B, as well as key metabolite, 5-aminolevulinic acid for plant growth at the maturity stage of compost.
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