Effects of pyroligneous acid as silage additive on fermentation quality and bacterial community structure of waste sugarcane tops

Abstract This article intends to improve the recycling of waste sugarcane (Saccharum officinarum) tops and the value-added utilization of pyroligneous acid. Fresh sugarcane tops can be used by ruminants, but they are prone to dehydration and mildew during storage, reducing their feeding value. Pyroligneous acid, a by-product in the process of making biochar, has good antibacterial effects. Adding pyroligneous acid to sugarcane tops for silage fermentation may be an effective way to promote the recycling of sugarcane tops. Thus, the fermentation quality and bacterial community of sugarcane tops ensiled with or without 1–2% pyroligneous acid for 5, 10, 20, or 100 days were investigated. Results showed that pyroligneous acid increased the acetic acid content and reduced ammonia-N concentration, and numbers of coliform bacteria and molds in sugarcane tops silages. On the other hand, the addition of pyroligneous acid decreased the diversity of bacteria in sugarcane-top silage. Pyroligneous acid decreased Firmicutes and Leuconostoc relative abundances while increasing Lactobacillus relative abundances. Fermentation was also limited by the addition of pyroligneous acid, which reduced metabolic activities during ensiling. Graphical abstract