3. (b) Discuss the production technology of rainfed cotton crop under the following heads: (i) Climate and soil requirement (ii) Methods of sowing and seed rate (iii) Manures and fertilizers (iv) Inter-culture operations (v) Plant protection

(i) Climate and Soil Requirement

Rainfed cotton thrives in specific climatic and soil conditions, which are critical for its growth and yield, especially given its dependence on monsoon rains.

• Climate:
  • Temperature: Cotton is a semi-xerophyte grown in tropical and subtropical conditions. It requires a minimum temperature of 15°C for germination, ideally 18-30°C. Optimal temperatures for vegetative growth are 21-27°C, while 25-35°C is ideal for robust vegetative growth and productive flowering. The fruiting period benefits from 80-90°F (26.7-32.2°C) with cool nights. A long growing period of at least 210 frost-free days is essential.
  • Rainfall: For rainfed cotton, an annual rainfall of 500 to 700 mm is ideally needed for healthy growth, with a well-distributed rainfall of about 125-150 mm per month during the growth period. Alternate rain and sunshine are beneficial. However, excessive or poorly timed rainfall, especially during flowering and boll development, can lead to boll rot, fungal diseases, and significant yield loss due to waterlogging.
  • Sunshine and Humidity: Long periods of heat with low humidity are conducive. High humidity during later stages can spoil the produce and promote pest/disease attacks.
• Soil:
  • Soil Type: Cotton can grow on a variety of soils, but deep, well-drained loamy soils rich in organic matter are considered ideal. Black clayey soils (Vertisols) of varying depths found in central India (Maharashtra, Gujarat, Madhya Pradesh) and mixed black and red soils in southern India (Telangana, Andhra Pradesh, Karnataka) are particularly suitable due to their high water-retention capacity.
  • Soil pH: A pH range of 6.0 to 7.5 ensures optimal nutrient availability and fiber formation. Acidic soils (pH < 6.0) may require lime incorporation (1-1.5 t/ha) 30-40 days before sowing.
  • Drainage: Proper drainage is vital as cotton is highly susceptible to waterlogging. Standing water for even 24 hours can cause root rot, stunted growth, and reduced lint production.
  • Texture and Depth: Deep soils encourage extensive root systems, while loamy structure balances drainage and moisture retention.

(ii) Methods of Sowing and Seed Rate

Appropriate sowing methods and seed rates are critical for establishing a healthy plant stand in rainfed cotton, maximizing the utilization of available moisture.

• Land Preparation: Fields should be ploughed to achieve a fine tilth immediately after the harvest of the previous crop. Adopting a permanent broad ridge system can be beneficial, especially in rainfed areas, to manage moisture.
• Timing of Sowing: For rainfed cotton, sowing typically commences with the onset of the South-West Monsoon, generally in June-July. Pre-monsoon dry sowing can be done in late May or early June if residual moisture is sufficient.
• Methods of Sowing:
  • Dibbling: This method involves placing seeds by hand at recommended spacings and is commonly practiced for hybrid varieties in rainfed areas. It ensures uniform plant population and better germination.
  • Tractor/Bullock Drawn Seed Drill: While often used for irrigated cotton, seed drills can also be adapted for rainfed conditions, particularly for varieties that require closer spacing. Line sowing ensures uniform spacing and reduced seed rate compared to broadcasting.
  • Ridge and Furrow Method: Sowing on ridges and furrows is often adopted, where plants occupy the middle of the ridge after earthing up. This helps in better moisture conservation and drainage.
• Seed Rate and Spacing: The seed rate and spacing vary depending on the variety (e.g., *arboreum*, *hirsutum*, or Bt hybrids), soil type, and cultivation practices. For dryland (rainfed) cotton, a seed rate of 12-16 kg/hectare is generally recommended, with spacing of 45-60 cm between rows and 15 cm between plants.
  • For *arboreum* (Desi) cotton, approximately 8 kg of fuzzy seeds per acre.
  • For *hirsutum* (American) cotton, about 8 kg of fuzzy or 6 kg of delinted seeds per acre.
  • For Bt cotton hybrids, 2 packets per hectare (each 500g, containing 450g Bt seed + 50g refugia seed) are common.
  • Optimum depth of sowing is generally 3-5 cm.

(iii) Manures and Fertilizers

Nutrient management is crucial for rainfed cotton, balancing soil health, plant vigor, and sustainable yields under variable moisture conditions. An integrated approach combining organic and inorganic fertilizers is often recommended.

• Organic Manures:
  • Farm Yard Manure (FYM): Apply 5-10 tonnes per acre (or per hectare, 10-12 tons) of well-decomposed FYM during land preparation, 15-20 days before sowing. FYM improves soil physical properties, organic carbon content, water retention, and provides a balanced source of macro and micronutrients.
  • Biofertilizers: Apply carrier-based formulations (e.g., 1 kg each of Azospirillum, Phosphobacteria, and Silicate Solubilizing Bacteria per acre mixed with 25 kg FYM and 25 kg sand) or liquid formulations (200 ml each per acre) at the time of last ploughing. These enhance nutrient uptake, especially nitrogen and phosphorus.
  • Green Manuring: In-situ green manuring with crops like sunhemp can improve soil health and nutrient availability.
• Inorganic Fertilizers:
  • General Recommendation: Based on soil analysis, a general recommendation for rainfed cotton hybrids is often around 80:40:40 kg NPK per acre. Some sources recommend 50:30:35 kg NPK per acre for summer season cotton.
  • Nitrogen (N): Nitrogen is a powerhouse nutrient for cotton, driving vegetative growth and boll formation. Excessive nitrogen can lead to rank growth and delayed maturity. For rainfed conditions, 50-80 pounds per acre (approx. 56-90 kg/ha) is often recommended. Apply in split doses:
    • Half dose at sowing.
    • Remaining half as top dressing during thinning or just before flowering.
  • Phosphorus (P): Supports root development and energy transfer. Cotton needs 20-40 pounds of P2O5 per acre (approx. 22-45 kg/ha). Apply pre-plant, ideally in bands near the seed row for efficiency on low-P soils.
  • Potassium (K): Crucial for fiber quality and disease resistance. Apply as per soil test recommendations, often in combination with P as a basal dose. Potassium is known to help reduce the incidence and severity of wilt diseases.
  • Micronutrients: Boron, Zinc, Sulphur, Calcium, and Magnesium are also essential. Boron is vital for boll setting, while Zinc Sulphate (e.g., 50 kg/ha as basal) can address zinc deficiency. These can be applied as foliar sprays or with basal fertilizer application.

(iv) Inter-culture Operations

Inter-culture operations are vital for rainfed cotton to manage weeds, conserve soil moisture, and ensure optimal growth, especially in the absence of assured irrigation.

• Weed Control: Weeds compete with cotton plants for moisture, nutrients, sunlight, and space, significantly impacting yield.
  • Manual Weeding/Hoeing: Essential, especially in the initial 6-8 weeks after planting. It can be repeated once or twice at 2-3 week intervals. Manual weeding also helps in soil aeration and acts as natural mulching in dry conditions.
  • Mechanical Weeding: Use of wheel hoes (hand-driven or bullock-drawn) reduces labor costs.
  • Chemical Weed Control: Pre-emergence herbicides like Pendimethalin (0.75 a.i./ha) or Oxyfluorfen (0.5 kg a.i./ha) can be applied. A combination of chemical and manual methods is often most effective.
• Thinning and Gap Filling:
  • Thinning: Removing excess seedlings to maintain optimal plant population and reduce intra-plant competition for resources. This is typically done within 15-20 days of sowing to achieve the desired plant-to-plant spacing (e.g., 15 cm).
  • Gap Filling: Replanting in areas where seeds failed to germinate or seedlings died, to ensure a uniform and optimum plant stand. This should be done as early as possible after assessing germination.
• Mulching: An important practice for rainfed crops. Applying organic mulches (e.g., crop residues, straw, water hyacinth) on the soil surface helps to:
  • Conserve soil moisture by reducing evaporation.
  • Suppress weed growth.
  • Moderate soil temperature.
  • Improve soil organic matter upon decomposition.
• Earthing Up: Lifting soil around the base of the plants to provide better anchorage, especially as plants grow taller and bear heavy bolls. This also helps in creating furrows for water collection during rainfall.
• Crop Rotation: Essential for sustainable cotton farming. Rotating cotton with non-host crops (e.g., cereals, pulses) helps break pest and disease cycles, improves soil fertility through nitrogen fixation (legumes), and manages weed populations.

(v) Plant Protection

Effective plant protection strategies are paramount for rainfed cotton, as these crops are more vulnerable to pests and diseases due to environmental stresses and reliance on unpredictable rainfall.

• Integrated Pest Management (IPM): A holistic approach combining cultural, mechanical, biological, and chemical methods.
  • Cultural Practices:
    • Crop Rotation: Prevents the build-up of specific pests and diseases.
    • Timely Sowing: Avoids peak pest incidence periods.
    • Field Sanitation: Removal of crop residues and weeds that harbor pests and pathogens.
    • Resistant Varieties: Planting pest and disease-resistant cotton varieties (e.g., Bt cotton for bollworm resistance, although unapproved HTBT cotton is widely grown due to perceived benefits in weed management and pink bollworm resistance to current approved Bt strains).
  • Mechanical/Physical Methods:
    • Hand Picking: Manual removal of visible insects or infected plant parts.
    • Pheromone Traps: For monitoring and mass trapping of male moths (e.g., for bollworms).
    • Bird Perchers: Encouraging predatory birds.
  • Biological Control:
    • Conservation and augmentation of natural enemies (predators and parasitoids) of pests.
    • Application of bio-pesticides like *Bacillus thuringiensis* (Bt) formulations for lepidopteran pests.
  • Chemical Control: Judicious use of pesticides as a last resort, based on economic threshold levels.
    • Seed Treatment: Application of fungicides and insecticides to seeds to protect against early seedling diseases and sucking pests.
    • Foliar Sprays: Application of recommended insecticides for sucking pests (aphids, jassids, whiteflies, thrips) and bollworms (e.g., pink bollworm, American bollworm). Timely spraying is crucial.
    • Fungicides: For fungal diseases like *Alternaria* leaf spot, anthracnose, or boll rot, systemic or protectant fungicides may be used, especially in periods of high humidity and rainfall.
• Disease Management:
  • Seedling Diseases: Damping-off, root rot. Managed by seed treatment, good drainage, and planting in warm, moist soil. Raised beds can improve soil warming and drainage.
  • Fungal Diseases: Boll rot, leaf spots. Control through good air circulation, appropriate plant spacing, avoiding excessive nitrogen, and fungicidal sprays during critical periods.
  • Bacterial Blight: Managed by resistant varieties and copper-based sprays.
  • Viral Diseases: Cotton Leaf Curl Virus (CLCuV). Managed primarily by controlling the whitefly vector and planting resistant varieties.
• Nutrient Management for Resistance: Adequate and balanced nutrition, particularly potassium, can help plants develop stronger resistance to certain diseases. Micronutrients like boron and calcium are also essential for plant health and stress tolerance.