Re-ensiling with urea, sweet corn ear tips, and calcium oxide enhances sweet corn stalk preservation and substrate quality for industrial bioconversion

Sweet corn stalk (SCS) is a lignocellulosic agricultural byproduct with considerable potential for industrial applications, yet its valorization is constrained by seasonal availability, rapid field spoilage, and the recalcitrant lignin–polysaccharide matrix. In this study, re-ensiling was conceptualized as an upstream preservation and in situ mild pretreatment unit within the biorefinery chain. Three additives, namely corn ear tips (CT), calcium oxide (CaO), and urea (NS), were applied to SCS during re-ensiling to evaluate their effects on fermentation characteristics, substrate physicochemical properties, aerobic stability, and bacterial community structure. The work aimed to elucidate, from the feedstock supply perspective, how re-ensiling strategies support the industrial value chain of SCS, and to assess the valorization potential of the modified substrates toward non-feed biorefinery applications. Results showed that each additive distinctly reshaped substrate physicochemical composition, aerobic stability, and bacterial communities, yielding modified substrates that could be differentially directed toward biorefinery routes such as alkaline pretreatment or anaerobic digestion. It should be emphasized that this study only characterized the substrate traits after re-ensiling; the actual bioconversion performance in downstream enzymatic saccharification and fermentation remains prospective and requires further experimental validation.