Critical level for hot water extractable B (ppm) in soil is

Correct option is C

✅ (c) 0.1–2.0 ppm [Boron Critical Level] • Boron (B) is a micronutrient required in small amounts, and its availability is often measured using hot water extraction. • The critical range for hot water-soluble boron is 0.1–2.0 ppm. • Below 0.1 ppm is typically considered deficient for most crops. • Excess boron (above 2.0 ppm) may become toxic, especially in sensitive crops.
❌ (a) 5.0–10.0 ppm • Falls within a toxic range for most crops. • Not considered critical or normal for boron availability.
❌ (b) 10.0–15.0 ppm • Highly toxic level of boron in soil. • May cause symptoms like leaf burn and reduced yield.
❌ (d) 2.0–5.0 ppm • Borderline or toxic depending on crop sensitivity. • Exceeds the critical level used to diagnose deficiency.