Silage pH is not a report card

Final pH matters, but crop, dry matter, acids, ammonia, and aerobic stability determine what that pH means.

4 min read · 2026-09-17

In this note

pH 3.7–4.2
4–7%

Corn silage and legume silage differ in buffering capacity and expected fermentation. A low final pH can sit next to excessive fermentation losses. A higher pH in a drier or highly buffered crop is not automatically failure. pH is a clue inside a pattern, not a grade on the silo.

Kung and Shaver read pH beside crop and dry matter, lactic and acetic acids, butyric acid, ammonia-N, alcohols, smell, and temperature. Well-preserved corn silage often lands near pH 3.7–4.2 with lactic acid around 4–7% of DM — those are pattern marks, not a pass/fail stamp for every crop. Do not treat final pH as a report card.

Check in the barn

What to check: Crop and DM first, then the acid profile, ammonia, and smell. Is butyric present? Is the face heating even if last month’s bag looked fine? Read the fermentation panel with the feed-out, not instead of it.

Sister notes on this universe cover the-fermentation-report-ends-at-feed-out and a-mold-count-is-not-a-mycotoxin-test. The inside-the-rumen universe’s air-at-the-face-spoils-the-pack note is the packing and face half of the same fermentation story. Educational only — not a diagnosis, prescription, or ration formula.