Jennifer and I have been getting questions about foliar feeding cotton. Below are some general guidelines and rules of thumb to follow as you use foliar fertilizer to help you finish the season.
Foliar Feeding General Guidelines:
- Supplement to a Good Soil Applied Program
- Not all Nutrients Feed Well
- Low Volume -Not Pivots
- Don’t feed when Stressed
- Need best determined by Tissue or Petiole Testing
General Rules of Thumb:
- Emphasis on N (Nitrogen) and K (Potassium/Potash) after Bloom
- Sulfur is hard to fix foliar
- Switch from Ground applied to Foliar after the 3rd Week of Bloom
- Fertilizer through a Pivot is ground applied (NOT Foliar)
- Foliar does Not cause vegetative or rank growth (Nutrients should reach the bolls within 48 hrs. You may not see it green up. That doesn’t mean it isn’t working.)
- Rainfastness – usually approx. 2 hours (until dry)
- Don’t foliar feed after 8th week of Bloom (Too Late)
Standard Foliar Recommendations for Cotton
(This information can be found in our Cotton Production Guide. You can get a copy at our office or download it here.)
N – Feed Grade Urea = 46 % N with Low Biuret
10 lbs in 12 gallons (gives 4.6 lb N/acre)
20 lbs in 20 gallons (max – gives 9.2 lb N/acre)
K – Potassium Nitrate = 13.5-0-46
10 lbs in 12 gallons (gives 4.6 lb K2O/acre)
20 lbs in 20 gallons (max – gives 9.2 lb K2O/acre)
B – Boron
- 0.5 lbs/acre applied in two 0.25 lb/acre foliar applications between first square and first bloom.
- Research shows all Boron products are equally effective in terms of plant nutrition and should be purchased by price per pound of B.
- Boron can help move Nitrogen from the leaves into the bolls.
- If no B is included in preplant, starter, or sidedress soil-applied fertilizer applications, is foliar B alone (with no insecticide or growth regulator) worth the trip? Yes, especially on sandier soils and with irrigation or adequate rainfall.