Sugarcane Cultivation : Using Biofertilizers for more crop yield

Sugarcane, the powerhouse of the world's sugar and biofuel industries, is a heavy feeder with a long growing cycle, making it highly susceptible to nutrient stress, pests, and diseases. While chemical inputs have traditionally dominated its cultivation, rising costs, environmental concerns, and soil degradation are pushing farmers toward a more sustainable path. Biofertilizers, Biopesticides, and Biofungicides offer a scientifically-backed, ecological solution to enhance productivity while safeguarding soil health for future ratoons.

This article explores the strategic use of these biological tools in a modern sugarcane program.

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I. Biofertilizers: Feeding the Crop & Rejuvenating the Soil

Biofertilizers are living microorganisms that enhance plant nutrient availability. For sugarcane, they are crucial for reducing nitrogen (N) and phosphorus (P) fertilizer bills and improving overall soil structure.

Key Types & Their Roles:

1. Nitrogen-Fixers:

   • Acetobacter diazotrophicus: The star biofertilizer for sugarcane. This bacterium lives inside the plant tissues (endophytic), fixing atmospheric nitrogen directly for the cane. It is highly effective, works well with low N inputs, and promotes growth hormones.

   • Azospirillum spp. & Azotobacter spp.: Rhizosphere bacteria that fix N in the root zone, solubilize phosphorus, and produce growth-promoting substances.

2. Phosphate Solubilizers/Mobilizers:

   • Bacillus megaterium, Pseudomonas striata, Trichoderma spp.: These microbes convert insoluble rock phosphate and fixed soil phosphorus into a plant-available form through acid production and enzymatic action. This is critical in alkaline and acidic soils where P gets locked up.

3. Potassium Mobilizers:

   • Frateuria aurantia, Bacillus mucilaginosus: These bacteria solubilize silicate minerals to release potassium (K), improving cane quality, sugar recovery, and stress tolerance.

4. Plant Growth-Promoting Rhizobacteria (PGPR) Consortia:

   • Multi-strain products containing mixes of the above bacteria plus others like Pseudomonas fluorescens. They provide a holistic benefit: N-fixation, P & K solubilization, and production of hormones (IAA) and siderophores that boost root growth and plant vigor.

Application: Best applied as setts treatment (dipping cuttings in a slurry) and soil application at planting or during ratoon management. This ensures early colonization and maximum benefit.

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II. Biopesticides: Targeted Pest Control with Natural Enemies

Sugarcane faces threats from borers (early shoot, top, and stalk borer), white grubs, and pyrilla. Biopesticides offer targeted, residue-free control.

Key Types & Their Targets:

1. Entomopathogenic Fungi:

   • Beauveria bassiana & Metarhizium anisopliae: Effective against white grubs, root borer, and sucking pests. The spores germinate on the insect cuticle, penetrating and killing it from within.

2. Entomopathogenic Bacteria:

   • Bacillus thuringiensis var. kurstaki (Bt): Highly effective against leaf-eating caterpillars and early-stage borers. The insect must ingest the bacterial toxin, which disrupts its gut.

3. Viruses:

   • Nuclear Polyhedrosis Virus (NPV): Species-specific viruses like Scirpophaga excerptalis NPV for top borer. The infected larvae disintegrate, releasing more virus particles into the crop canopy.

4. Botanicals & Oils:

   • Neem-based products (Azadirachtin): Acts as an antifeedant, growth regulator, and repellent against a broad spectrum of pests like borers and pyrilla.

   • Karanja oil: Has pesticidal and fungicidal properties.

Application: Timely application based on pest scouting is crucial. Spray during cooler parts of the day for fungal agents. For soil pests like grubs, apply Beauveria/Metarhizium mixed with organic manure to the soil.

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III. Biofungicides: Combating Soil and Stalk-Borne Diseases

Red rot, smut, wilt, and grassy shoot are major fungal/bacterial diseases. Biofungicides work through competition and direct antagonism.

Key Types & Their Mode of Action:

1. Antagonistic Fungi:

   • Trichoderma harzianum, T. viride, T. asperellum: The workhorses of biofungicides. They act via mycoparasitism (attacking pathogen hyphae), competition for space/nutrients, and inducing systemic resistance in the plant. Effective against soil-borne pathogens causing wilt and root rots, and can suppress red rot.

2. Antagonistic Bacteria:

   • Pseudomonas fluorescens & Bacillus subtilis: Produce a battery of antibiotics, siderophores, and lytic enzymes that inhibit fungal and bacterial pathogens. Excellent for sett treatment to prevent fungal colonization and for soil application.

Application:

• Sett Treatment: Dipping setts in a solution of Trichoderma + Pseudomonas is the single most important prophylactic step against red rot and smut.

• Soil Application: Incorporated into the soil at planting to build a protective rhizosphere.

• Foliar Spray: For managing foliar diseases, though less common.

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Integrating Bio-Inputs into a Sugarcane Management Schedule

The Bottom Line

The shift to bio-inputs in sugarcane is not about complete and immediate replacement of chemicals, but about strategic integration. Starting with sett treatment and soil application builds a foundation of soil health and plant resilience, leading to:

• Reduced dependency on synthetic fertilizers (especially N & P) by 20-30%.

• Effective, eco-friendly pest and disease suppression.

• Improved soil organic matter and microbial diversity.

• Better ratoon longevity and higher sucrose content.

By adopting these biological tools, sugarcane farmers can cultivate a more profitable, sustainable, and resilient crop system, ensuring that both their fields and their futures remain productive for seasons to come.