Effects of Food Waste Substitution for Tail Vegetables on Compost Quality and Bacterial Community Characteristics During Sheep Manure-Based Composting

Composting formulations that combine livestock manure with locally available organic residues may improve waste recycling, but the effects of replacing vegetable residues with pretreated food waste depend on the co-substrate combination. This study compared four sheep-manure-based formulations containing tail vegetables (TVs) or pretreated catering food waste (PCFW), with or without corn straw (CS): SM-TV, SM-TV-CS, SM-PCFW, and SM-PCFW-CS. Temperature profiles, endpoint physicochemical properties, germination index (GI), and bacterial communities were assessed. Replacing TV with PCFW was associated with a higher peak temperature and higher final electrical conductivity (EC), whereas GI did not differ significantly between SM-PCFW and SM-TV. Among the four formulations, SM-PCFW-CS had the lowest final EC (3.04 mS cm−1) and the highest GI (1.044); it also had the longest period above 50 °C. Endpoint community composition showed an overall formulation effect (PERMANOVA, pseudo-F(3,8) = 4.014, R2 = 0.601, p = 0.0002), although no pairwise exact comparison was significant after adjustment. In exploratory community–environment analyses of 12 endpoint piles, pH, EC, and alkali-hydrolyzable nitrogen (AN) were associated with community variation in redundancy analysis, and AN was associated with phylum- and genus-level community distances in Mantel tests. No taxon–environment Pearson correlation remained significant after false-discovery-rate correction. Although the small number of independent piles limits mechanistic inference and generalization, the results support considering pretreated food waste as a conditional substitute for vegetable residues in sheep manure composting. Under the tested conditions, the formulation combining pretreated food waste and corn straw achieved the lowest endpoint EC and highest GI, providing a candidate formulation for further validation when vegetable residues are unavailable.