Cotton Research

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Cotton Research

• Oklahoma State University

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Exp. 439, Altus OK 1972-2006
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Exp. 439, Altus OK 1972-2006
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Exp. 439, Altus OK 1972-2006
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N Rate Algorithm Trial

• Location Lake Carl Blackwell
• Plot Size 20 x 10
• Alley width 5
• Total area 95 x 150
• Planting Date May 15, 2006
• Harvest Date October 9, 2006
• Fertilizer P applied preplant and incorporated,
  30 lb P2O5/ac as 0-46-0
• Tillage 2 discs preplant followed by a rolling
  coulter

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Treatment Structure
TRT Preplant N Rate Topdress N Rate Growth Stage PIX
1 0 0 - As needed
2 50 0 - As needed
3 100 0 - As needed
4 150 0 - As needed
5 200 0 - As needed
6 50 50 Early square As needed
7 50 100 Early square As needed
8 50 150 Early square As needed
9 0 100 Early square As needed
10 0 150 Early square As needed
11 0 200 Early square As needed
12 0 SBNRC Early square As needed
13 50 SBNRC Early square As needed
14 50 0 PIX
15 200 0 No PIX
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N Rate Algorithm Trial

• Variety Monsanto NG3273B2RF
• The Cotton Variety was NexGen 3273B2RF.  It is a
  stacked trait variety with Roundup-Ready Flex
  (allows for multiple applications of Round-up
  throughout the growing season) and Bollgard 2
  (newest Bt product for cotton).  NexGen cotton
  varieties are stripper varieties

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If too much N has been applied what are the
visible indicators?

• Delayed maturity
• Compared to zero-N plots
• Leaf N will be higher in the over-fertilized
  plots

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If not enough N has been applied, and more is
needed mid-season,what should we look for?

• Leaf N lt 90-95 of over-fertilized plots or
  strips.
• New fruits can shed
• Developing bolls will be smaller

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What to do?
ENVIRONMENT ?

• Zero-N Strip
• Farmer Practice
• Nitrogen Rich Strip
• N management in Texas and Oklahoma is too N rich.
  

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• Improved Mid-Season N Management
• Can we estimate RI in cotton similar to wheat and
  corn?
• Can we estimate yield potential and use a YP0
  RI algorithm approach?
• The Ramp Calibration Strip should help us to
  define optimum N rates and to avoid excessive
  vegetative growth

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N Management

• Preplant Soil Test 0-24
• Dryland 30-50 lb N/acre
• Irrigated 60 lb N/bale of yield goal
• Mid-season N (June, 1st square)
• Use of N Rich and 0-N (visual)
• Last N Applied (peak bloom)

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Sensor Based N Algorithm

• On-off based on vegetative Green optimum and
  coverage threshold
• On-off decision of if/then, and/or for N or
  growth regulator
• To start, these decision tools need to be simple
  (yes/no). Management zones, (high-med-low)
  approaches can come later.