The most effective amendment used for alkali (sodic) soil reclamation is:

Correct option is B

· Alkali (sodic) soils have high ESP, high SAR, high Na⁺ on exchange sites.
· Gypsum (CaSO₄·2H₂O) provides Ca²⁺, which replaces Na⁺ on the exchange complex.
Why other options are wrong
· (a) Lime is used for acid soils, not sodic.
· (c) Elemental sulfur creates acidity; useful for alkaline soils but ineffective for sodic soil Na⁺ displacement.
· (d) FYM improves structure but cannot reclaim sodicity alone.