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Abstract. High biogas yield from agricultural waste is one of the prominent ways to improve green energy generation, which could potentially encourage energy diversification from fossil fuel. This study considered corn stover (Cs) pretreatment with 8% calcium hydroxide (8% Ca(OH)₂), 4% sodium hydroxide (4% NaOH), 2% aqueous ammonia (2% NH₄OH) or 4% aqueous ammonia (4% NH₄OH) prior to co-digestion with dairy manure (Dm) to improve biogas yield and as well achieved suitable process threshold parameters (volatile fatty acids (VFA), ammonia, alkalinity). Hence, treatments in this solid-state anaerobic digestion (SSAD) study were 4%NaCsDm, 2%NH₄CsDm, 4%NH₄CsDm, and 8%CaCsDm. The result indicated that 8%CaCsDm was the best treatment due to the high biogas and methane yield (351 and 179 L/kg VS), no obvious VFA accumulation, and least hydraulic retention time (79 days) compared to other treatments. Furthermore, suitable thresholds for VFA/ammonia, VFA/alkalinity, and propionic/acetic acid ratio were between 0.4 – 4.5, 0.2 – 1.3, and 0.0 – 0.2, respectively. Therefore, calcium pretreated corn stover.