Magnesium for Wheat: Soil Test First, Then Decide

Magnesium (Mg) needs for wheat cultivars cannot be generalized—application rates of MgSO₄·7H₂O depend entirely on soil test results.

Why Soil Testing Is Essential

• Most soils contain adequate Mg; deficiency is rare except in acidic, sandy, or heavily leached soils.
• High soil pH (>7.0) can induce Mg deficiency even when Mg is present (cation competition).
• Excess potassium or calcium can block Mg uptake.

What a Soil Test Reveals

• Extractable Mg level (ppm).
• Cation exchange capacity (CEC) and base saturation percentages.
• pH and lime requirement.
• Crop-specific Mg recommendation (lbs/acre).

If Deficiency Is Confirmed

• Soil application: 20–40 lbs Mg/acre as MgSO₄ (Epsom salt) or K-Mag.
• Foliar spray: 1–2% MgSO₄ solution at tillering and jointing for quick correction.
• Lime with dolomitic limestone if pH is also low.

Key Point

Blind application wastes money and can imbalance other nutrients. Test soil, follow local Extension recommendations.