Mn toxicity in soils occurs mainly under:

Correct option is B

· Manganese becomes highly soluble in acid (low pH) and reduced (poorly aerated/waterlogged) soils.
· Mn²⁺ increases → plant toxicity.
Why other options are wrong
· (a) High pH reduces Mn solubility.
· (c) Neutral soils rarely show Mn toxicity.
· (d) Calcareous soils tie up Mn → deficiency, not toxicity.