Siregar, R. and Sinaga, K. 2026. The Effect of Fermentation Duration on the NPK Content and C/N Ratio in Chicken Manure Using M21. Jurnal Multidisiplin Dehasen (MUDE). 5, 3 (May 2026), 1375-1382. DOI:https://doi.org/10.37676/mude.v5i3.11391.