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First-dose fertilizer schedule in cotton

Indian package-of-practice schedules for Bt cotton split the nitrogen budget across basal, early-vegetative and squaring/flowering applications, with phosphorus and potassium supplied entirely at basal. The first dose covers the basal NPK plus a micronutrient correction at sowing and a top-dressing of urea three to four weeks later.

Principle

Cotton requires phosphorus and potassium to be positioned in the root zone early because both nutrients are immobile and key to root development and boll-loading respectively. Nitrogen is split because Bt cotton is sensitive to excess early-season N — which provokes rank vegetative growth and aggravates sucking-pest pressure — but needs sustained N supply through squaring and flowering.

Implementation

For Bt cotton the recommended dose is approximately 49:24:24 kg NPK per acre, delivered as follows:

  • Basal (at or just before sowing): about 50-60 kg DAP, 20-25 kg muriate of potash and 10 kg zinc sulphate per acre, banded along the row and incorporated.
  • First top-dressing (20-30 DAS, early vegetative): about 30-40 kg urea per acre, side-dressed and incorporated with inter-cultivation or hoeing.
  • Subsequent doses (squaring/flowering): the balance of urea, supplemented by foliar potassium nitrate during boll development.

The first dose pairs naturally with the early-season weed and crop-management sequence in Cotton First 30 Days Management.

Adoption context

The schedule is adapted from the vikaspedia/CICR package-of-practice for Maharashtra and is broadly applicable to Telangana, Andhra Pradesh and Karnataka. Adjustments are recommended on the basis of soil test, residual fertility from the preceding crop and irrigation regime (rainfed cultivation usually trims potash and N rates).

Limitations

Bt cotton on light soils or under drip irrigation benefits from further splitting through fertigation. Excess basal nitrogen on rich Vertisols is a common error and predisposes the crop to sucking-pest flares.

See also Cotton First 30 Days Management, Cotton Topping Pinching, Bt Cotton Bg Ii, Cotton Spacing Row Options.

References

  1. Package of practices for Cotton: Maharashtra State. vikaspedia.
  2. Growing Conditions And Nutrient Requirements Of Bt Cotton. Kisanvedika.