Sugarcane Ratoon Chlorosis: Soil & Foliar Fertilizer Schedules to Maximize Brix Sugar

In commercial sugarcane cultivation across Maharashtra, Gujarat, Uttar Pradesh, and Karnataka, maintaining profitable ratoon crops is fundamental to plantation economics. Ratooning saves land preparation and seed sett costs, allowing growers to harvest consecutive crops from existing root stools. However, second and third ratoon crops frequently exhibit severe interveinal chlorosis, stunted cane elongation, and thin internodes—a condition known as Sugarcane Ratoon Chlorosis.

1. The Causes of Micronutrient Starvation in Ratoon Crops

Unlike plant cane, ratoon crops rely on an aged, partially decomposed root system that must quickly generate new feeder roots in compacted, depleted subsoils:

• •Subsoil Iron Immobilization: Subsurface soil compaction restricts soil aeration. In alkaline, calcareous clay soils, divalent iron (Fe2+) oxidizes into insoluble ferric precipitates that the stubble root system cannot scavenge.

• •High Zinc Depletion: Plant cane harvests remove over 600 grams of pure zinc per hectare. Without targeted replacement, ratoon stubbles suffer severe auxin deficiency, suppressing tillering and cane girth.

2. Direct Impact on Cane Tonnage & Sugar Recovery (Brix %)

Iron and Zinc are mandatory catalytic cofactors for Sucrose Phosphate Synthase (SPS)—the enzyme responsible for synthesizing and storing sucrose in sugarcane stalk parenchyma cells:

• •Stalk Girth Reduction: Iron-deficient ratoon canes exhibit thin, fibrous stalks with reduced juice extraction percentages.

• •Mill Sugar Recovery Loss: Uncorrected chlorosis lowers the industrial Brix % and Pol % by 1.2% to 2.5%, triggering penalty deductions from sugar mill purchase payments.

3. The 3-Step Ratoon Remediation Protocol

1. Stubble Shaving & Trash Management: Shave stubbles close to the ground level and incorporate cane trash into inter-row spaces using rotavators. 2. Basal Off-Barring Soil Application: Apply 15 kg/acre of Ferrous Sulphate Heptahydrate 19% and 10 kg/acre of Zinc Sulphate Monohydrate 33% mixed with 200 kg of well-rotted pressmud (filter cake) or vermicompost along the stubble rows. 3. Foliar Rescue Spray Schedule: • Spray 1 (45 Days After Ratooning): Dissolve 5g Ferrous Sulphate 19% + 3g Zinc Sulphate 33% + 2g Citric Acid + 10g Urea per liter of water. • Spray 2 (75 Days After Ratooning): Repeat during active grand growth phase to maintain dark green canopy photosynthesis.

4. Field Results & Economic Gains

Commercial field trials show that implementing this dedicated micronutrient schedule restores dark green chlorophyll within 5 days, increasing ratoon cane yields by 8 to 14 Metric Tons per acre and elevating sugar recovery by 0.8% to 1.4%.

5. Frequently Asked Questions (FAQ)

• •Q: Why is Citric Acid added to the sugarcane ferrous spray?

• •A: Sugarcane leaves have a thick waxy cuticle. Citric acid acts as a natural chelating agent and acidifier, maintaining iron in the divalent (Fe2+) state for rapid cellular uptake.

• •Q: Can Ferrous Sulphate be applied through drip irrigation in sugarcane?

• •A: Yes, pure Auron Ferrous Sulphate Heptahydrate is 100% water-soluble and can be fertigated through drip systems when buffered with citric acid.