Which Is Better for Mango Trees During Summer?

Summer is the most stressful season for mango trees. High temperature, strong sunlight, and limited soil moisture reduce nutrient uptake, disturb water transport, and increase fruit drop. Among potassium fertilizers, Potassium Nitrate (KNO₃) and Potassium Sulphate (K₂SO₄) are commonly used — but they do not work the same way in summer.

This article explains which one to use, when, and why.

Why Potassium Is Critical in Summer

Potassium (K) controls:

• Water movement inside the tree (osmotic regulation)

• Stomatal opening and closing

• Sap flow from roots to leaves and fruits

• Heat and drought tolerance

• Sugar transport to developing fruits

Without enough potassium in summer:

• Leaves wilt faster

• Fruits drop or stay small

• Trees suffer heat stress even with irrigation

1. Potassium Nitrate (KNO₃)

Composition

• Nitrogen (N): ~13%

• Potassium (K₂O): ~46%

How It Works in Mango Trees

• Nitrate nitrogen increases root activity

• Promotes strong sap flow and water uptake

• Improves leaf turgidity and canopy freshness

Benefits in Summer

✅ Boosts water transport from roots
✅ Helps trees recover from heat shock
✅ Keeps leaves green and active

Risks in Hot Season

⚠️ Extra nitrogen increases transpiration
⚠️ Can stimulate unwanted vegetative growth
⚠️ May increase fruit drop if used late

Best Summer Use

• Early summer

• Post-harvest recovery

• Before flowering initiation

• Only when trees are well irrigated

2. Potassium Sulphate (K₂SO₄)

Composition

• Potassium (K₂O): ~50%

• Sulphur (S): ~18%

How It Works in Mango Trees

• Improves cell osmotic balance

• Helps regulate stomatal closure

• Reduces water loss during heat stress

Benefits in Summer

✅ Better drought and heat tolerance
✅ Improves water-use efficiency
✅ Supports fruit retention and size
✅ No excess vegetative growth

Limitations

⚠️ Does not stimulate root water uptake like nitrate
⚠️ Slower visible greening effect

Best Summer Use

• Mid to late summer

• Flowering and fruit development

• Dry or water-limited conditions

Direct Comparison for Summer Mango Management

Final Recommendation for Summer Mango Trees 🌳

👉 Do NOT rely on only one source

Best Practical Strategy

• Early summer:
  Small dose of Potassium Nitrate to activate roots and sap flow

• Main summer & fruiting period:
  Switch to Potassium Sulphate to protect against heat stress and reduce water loss

This approach keeps mango trees hydrated, stable, and productive during extreme heat.

Simple Foliar Spray Guide (Summer Safe)

• Early summer:
  KNO₃ → 1–1.5 g/L

• Fruit stage & peak heat:
  K₂SO₄ → 2–3 g/L

• Spray early morning or late afternoon

• Always ensure adequate soil moisture