SAR of alkali soils typically exceeds:

Correct option is C

· Alkali/sodic soils are defined by SAR > 13
· ESP > 15 and pH > 8.5 commonly accompany SAR > 13.
Why other options are wrong
· (a) 5 = normal soil.
· (b) 10 = elevated but not sodic threshold.
· (d) 26 = very strongly sodic, but classification threshold starts at 13.