How to Diagnose & Correct Iron Chlorosis with Ferrous Sulphate Heptahydrate & Monohydrate

Iron deficiency—commonly referred to as Iron Chlorosis—is one of the most visible and economically damaging nutritional disorders in commercial agriculture. It is particularly rampant across alkaline, calcareous soils (pH > 7.5) throughout Gujarat, Maharashtra, Rajasthan, and central India.

1. Diagnosing Iron Chlorosis in the Field

Because iron is an immobile micronutrient within plant vascular systems, it cannot be scavenged from mature bottom leaves to feed young growth. As a result:

• •Early Symptom: Interveinal chlorosis on the youngest terminal leaves (leaf tissue turns vivid canary yellow while veins remain sharply green).

• •Severe Symptom: Leaves turn bleached white, leaf margins develop necrotic brown burn, shoots undergo dieback, and flowering drops prematurely.

• •Differential Diagnosis: Nitrogen deficiency shows yellowing on the oldest bottom leaves first, whereas Iron deficiency exclusively strikes the newest top shoots.

2. Ferrous Sulphate: Heptahydrate 19% vs Monohydrate 30%

Ferrous Sulphate is the most bioavailable inorganic salt used to supply divalent iron (Fe2+) directly to crops:

• •Ferrous Sulphate Heptahydrate 19% (FeSO4 · 7H2O): Translucent light-green crystals containing 19.0% elemental Iron (Fe) and 10.5% Sulphur (S). Highly water-soluble, ideal for soil application and foliar sprays.

• •Ferrous Sulphate Monohydrate 30% (FeSO4 · H2O): Off-white/buff granular powder containing 30.0% elemental Iron (Fe) and 17.0% Sulphur (S). Ideal for dry NPK bulk blending and animal feed premixes.

3. Application Rates & Soil Remediation Protocol

• •Basal Soil Application: Apply 10 to 15 kg per acre of Ferrous Sulphate 19% mixed with 100 kg of well-decomposed FYM (Farmyard Manure). Organic humic acids chelate the iron and protect it from alkaline lock-up.

• •Emergency Foliar Rescue Spray: Dissolve 5 grams of Ferrous Sulphate 19% + 2 grams of Citric Acid per liter of water (0.5% concentration). Spray early morning. Citric acid maintains iron in the soluble divalent (Fe2+) state for rapid leaf uptake.

4. High-Response Crops

Sugarcane, Groundnut (Peanuts), Paddy Rice, Soybean, Citrus orchards, and Greenhouse Roses show immediate greening within 72 hours of application.