Fertiliser Management for Sugarcane

Understanding Sugarcane's Nutrient Needs

Sugarcane primarily requires three macronutrients: Nitrogen (N), Phosphorus (P), and Potassium (K), along with several micronutrients.

• Nitrogen (N): Essential for vigorous vegetative growth, tillering, and leaf development. Too much nitrogen, especially late in the season, can reduce sugar content.

• Phosphorus (P): Crucial for strong root development, early growth, energy transfer, and stalk formation. It helps in efficient nutrient uptake.

• Potassium (K): Plays a key role in sugar formation and translocation, water regulation within the plant, and improving resistance to drought, pests, and diseases.

• Micronutrients: Zinc (Zn), Iron (Fe), Manganese (Mn), Boron (B), and Copper (Cu) are needed in smaller quantities but are equally important for various metabolic functions and overall plant health. Zinc deficiency is common in many Indian soils.

Recommended Fertiliser Doses and Timing

The exact fertiliser dose depends on soil test results, sugarcane variety, previous crop, and irrigation availability. However, general recommendations for plant cane are often provided as a starting point.

NutrientRecommended Dose (kg/hectare)Application TimingNitrogen (N)150-250Split into 2-3 applications: 1/3 at planting, 1/3 at tillering (45-60 DAP), 1/3 during grand growth (90-120 DAP)Phosphorus (P)60-80Full dose as basal application at plantingPotassium (K)80-120Split into 2 applications: 1/2 at planting, 1/2 at tillering/grand growthZinc (Zn)10-25 (as ZnSO4)Basal application at planting or foliar spray if deficiency appears

For ratoon crops, Nitrogen and Potassium doses are often increased by 25% to compensate for the residual stubble and faster initial growth.

Application Methods

The method of fertiliser application impacts its efficiency and availability to the plant.

• Basal Application: Fertilisers like Phosphorus and part of Nitrogen and Potassium are applied at the time of planting, usually in furrows next to the setts.

• Top Dressing: Remaining doses of Nitrogen and Potassium are applied by broadcasting between rows or band placement near the root zone during later growth stages. Ensure adequate moisture after application.

• Foliar Spray: Micronutrients, and sometimes N and K, can be applied as foliar sprays, especially when deficiencies are observed or for quick uptake.

• Fertigation: In drip irrigation systems, water-soluble fertilisers can be applied directly to the root zone through irrigation water, leading to higher nutrient use efficiency.

Factors Influencing Fertiliser Requirements

Several factors can alter the optimal fertiliser schedule for your sugarcane crop:

• Soil Type: Sandy soils leach nutrients faster and may require more frequent, smaller doses. Clayey soils retain nutrients better.

• Soil Test Report: This is the most accurate way to determine nutrient deficiencies and excesses in your specific field. Always get your soil tested.

• Sugarcane Variety: Different varieties may have varying nutrient demands.

• Crop Stage: Nutrient requirements change significantly from germination to grand growth and maturity.

• Irrigation Availability: Adequate moisture is essential for nutrient uptake. In rainfed conditions, adjust application timing to coincide with rainfall.

• Ratoon Crop: Ratoon crops generally require higher nitrogen and potassium to support rapid regrowth.

Recognizing Nutrient Deficiency Symptoms

Observing your plants can give early clues about nutrient deficiencies:

• Nitrogen: Older leaves turn pale green to yellow, stunted growth, thin stalks.

• Phosphorus: Leaves may appear purplish or dark green, stunted growth, poor tillering, delayed maturity.

• Potassium: Yellowing and browning of older leaf margins, starting from the tip, followed by scorching. Stalks may be thin and prone to lodging.

• Zinc: Whitish or chlorotic bands on the leaves, especially near the midrib of younger leaves; stunted growth.

• Iron: Yellowing of young leaves (interveinal chlorosis) while veins remain green.

By carefully managing fertiliser application based on soil tests and plant observations, farmers can ensure their sugarcane crop receives the necessary nutrition for robust growth and high sugar yields. A balanced approach to fertilisation is key to sustainable and profitable sugarcane farming.