Sianipar, Ebsan Marihot, Sumihar Hutapea, Ernitha Panjaitan, and Siti Mardiana. “Applicability Assessment of Oil Palm Trunk Biochar for Use as Soil Amendment: Morphology, Structure, and Chemical Properties”. Science & Technology Asia 29, no. 1 (March 29, 2024): 256–270. accessed August 26, 2026. https://ph02.tci-thaijo.org/index.php/SciTechAsia/article/view/250287.