Cotton is a high-value cash crop grown in over 80 countries. Proper fertilization directly affects lint yield, fiber length, strength, and micronaire — the key quality parameters that determine market price.
Cotton Nutrient Requirements
A cotton crop yielding 2,500 kg/ha of seed cotton removes approximately:
- Nitrogen (N): 120-180 kg/ha
- Phosphorus (P2O5): 50-80 kg/ha
- Potassium (K2O): 100-180 kg/ha
- Sulphur (S): 15-25 kg/ha
- Boron (B): 0.5-1.0 kg/ha
Nitrogen Management for Cotton
Cotton has a unique nitrogen response — too much nitrogen promotes excessive vegetative growth (tall, leafy plants) at the expense of boll development. Apply Urea 46-0-0 in split applications:
- At planting: 20-30% of total N as basal
- Square formation (35-45 days): 40-50% of total N
- Early flowering (60-70 days): Remaining 20-30% of total N
Stop nitrogen application after peak flowering to promote boll filling and fiber maturation.
Phosphorus for Root and Boll Development
Phosphorus is critical for early root establishment, flowering, and boll retention. Apply DAP 18-46-0 at 150-250 kg/ha as basal dressing. All phosphorus should be applied at planting since it moves very slowly in soil.
Potassium for Fiber Quality
Potassium is essential for fiber strength, length, and boll opening. Apply MOP 0-0-60 at 100-200 kg/ha, split between basal application and first square formation stage. Potassium deficiency causes premature leaf senescence and reduced boll weight.
Recommended Cotton Fertilizer Programs
Conventional Cotton
- Basal (at planting): 200 kg/ha DAP + 100 kg/ha MOP + 50 kg/ha Urea
- First square (35-45 days): 150 kg/ha Urea + 50 kg/ha MOP
- Peak flowering (60-70 days): 100 kg/ha Urea
High-Density/High-Yield Cotton
- Basal: 250 kg/ha NPK 15-15-15 + 100 kg/ha MOP
- Square formation: 200 kg/ha Urea + 100 kg/ha NPK 17-17-17
- Flowering: 100 kg/ha Urea + 50 kg/ha MOP
Micronutrients for Cotton
Cotton is sensitive to boron and zinc deficiencies. Boron deficiency causes square abortion and reduced boll set. Apply borax at 5-10 kg/ha or foliar spray at flowering. Zinc deficiency appears in alkaline soils — apply zinc sulphate at 25 kg/ha as basal dressing.
Common Fertilizer Mistakes in Cotton
- Excessive nitrogen — promotes rank vegetative growth, delays maturity, reduces fiber quality
- Skipping potassium — reduces boll weight, fiber strength, and causes premature defoliation
- Ignoring boron — widespread deficiency causing square shedding and poor boll set
- Late nitrogen application — delays boll opening, increases pest pressure, and reduces harvest quality
Bulk Fertilizer Supply for Cotton
Thai Fertilizer supplies all cotton fertilization products in bulk from Thailand. Contact us for quotations on Urea, DAP, MOP, NPK blends, and micronutrients.