3.Acidogenic fermentation process

Microorganisms utilize sugars in the straw as substrates and convert them into organic acids. After aerobic fermentation of the straw, oxygen is exhausted and aerobic microorganisms cannot survive. Under anaerobic conditions, anaerobic microorganisms cannot completely convert sugar substrates into water and carbon dioxide, but can only be decomposed into various organic acids, including hexanoic acid, propionic acid, lactic acid, and butyric acid. These organic acids are ionized in the straw to form a large amount of hydrogen ions, which acidify the straw and decrease the pH value. When the pH value drops to 4.5–5.0, acidity inhibits the activities of various microorganisms, thus slowing down the microbial activities and forming a good straw silage.
