Yoanma, A. D., Haryanto, A., Oktafri, O., & Triyono, S. (2022). Effect of Coconut Shell Biochar Application on the Effectivity of NPK Fertilizer in Red Onion (Allium ascalonicum L.) Cultivation. Jurnal Teknik Pertanian Lampung (Journal of Agricultural Engineering), 11(1), 1–14. https://doi.org/10.23960/jtep-l.v11i1.1-14