Manganese is needed in small quantities, but it performs essential work in photosynthesis, enzyme activation and plant defence. John Kempf’s article focuses on “hidden hunger”: a crop can be short of a nutrient and lose performance before it develops the textbook symptoms that make the problem easy to recognise.
Availability matters more than the total in soil
A soil test may show that manganese is present while the crop still struggles to access it. Availability changes with pH, oxygen conditions, moisture, microbial activity and the element’s oxidation state. High-pH or heavily aerated conditions can convert manganese into forms that roots take up less readily, while waterlogging can create a different set of risks.
Kempf describes subtle crop signals and the physiological processes that can slow before a dramatic visual deficiency appears. That makes early diagnosis important: by the time symptoms are unmistakable, some yield potential or disease resilience may already have been lost.
Confirm the diagnosis
Visual symptoms alone can be misleading because nutrient disorders, root damage and disease often look similar. Tissue analysis, interpreted alongside soil results and field history, gives a firmer basis for action. Comparison strips can then show whether a foliar or soil-applied treatment produces a meaningful response.
This is agronomic commentary from John Kempf rather than a universal fertiliser recommendation. Product choice, rate and timing should reflect the crop, local soil chemistry and professional advice. The practical message is to look for functional deficiency early and correct the cause where possible, not merely chase a colour change.