What does a high pH value tell us about the fermentation process and silage quality?
The pH of an ensiled sample is a measure of its acidity, but is also affected by the buffering capacity of the crop. Two samples may have the same pH, but different concentrations of acids. In general, legume silages have a higher pH than corn or other grass silages and take longer to ensile because of their higher buffering capacity. Seldom do corn silages have a pH higher than 4.2. Such cases may be associated with extremely dry (>42% dry matter) silages that are overly mature or drought stricken. Because of its normally low pH (3.8), corn silage intake usually benefits from the addition of sodium bicarbonate prior to feeding to neutralize its acidity. Common reasons for legume silages having a pH higher than 4.6 to 4.8 include: ensiling at <30% dry matter (DM) which causes a clostridial fermentation, and ensiling at >45-50% DM, which restricts fermentation. In the first example, a high pH due to clostridia is a definite indicator of an undesirable fermentation that has led to poor q
