Development of a SBNRC Calculator for Cotton

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Development of a SBNRC Calculator for Cotton

• D. Brian Arnall
• Oklahoma State University
• W. Raun, J. Solie, M. Stone, R. Taylor, O.
  Walsh, D. Edmonds, C. Daft, B. England,Y. Kanke,
  B. Desta

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Fertilizer N Needs in Cotton

• Under Estimation of N Fertilizer and Application
  of an Insufficient Rate 
• Loss of Yield, proportional to shortfallConsumpti
  on of Soil N reserve, depletion of soil fertility
• Over Estimation of N Fertilizer Needs and
  Application of a above-optimal Rate
• Excess Vegetative Growth, Increased Plant Growth
  Regulation RequiredIncreased Susceptibility to
  AphidsIncreased Susceptibility to Boll
  RotDelayed Crop MaturityIncreased Difficulty to
  DefoliatePotential for Long-Term Decrease in
  Soil Organic MatterIncreased Need for Liming,
  through Soil Acidification 
• Cotton Corp
• Estimating Cotton's Nitrogen Needs
• R.L. Nichols, Cotton Incorporated and C.J. Green,
  Texas Tech University

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Sensor Based Nitrogen Rate Calculator

• What is needed.
• Yield Prediction Model
• Response Index
• Nitrogen Removal
• Nitrogen Use Efficiency.
• N Rate (YP0 RI YP0) N / Efficiency

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Cotton YP Trial
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Cotton N study
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The Experimental Sites

• 2006
• 1 Site Lake Carl Blackwell (LCB)
• 2-4.D
• Late Season Stress
• 2007
• 3 sites LCB YP, Altus 439, and Altus N study
• NDVI collected over and between rows
• 2008
• 4 sites LCB Irrigated YP, LCB Dryland N study,
  Altus 439, and Altus N study

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Data Collection
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Response in 2007
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Yield Potential Model

• Why use YP.
• Nitrogen is a model nutrient and according to
  Bray need is yield dependent.
• Using NDVI as a function of GDD.
• Days from Planting or Cumulative GDD

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Yield Potential Model
Winter Wheat
Units biomass, kg/ha/day, where GDDgt0
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INSEY DFP

• Relationship between in season estimate of yield
  (INSEY) computed from NDVI
• readings of cotton collected between 60-80 days
  after planting, divided by the
• number of days of planting to sensing, and
  measured lint yield from all site years.
• Where YP0 yield potential YP0 calculated the
  mean one standard deviation.

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INSEY Cum GDD

• Relationship between in season estimate of yield
  (Cum INSEY) computed from
• NDVI readings of cotton at growth stages from
  square to peak bloom (800-1300
• Cumm GDD), divided by the number of days of
  planting to sensing, and measured
• lint yield from all site years. Where YP0
  yield potential YP0 calculated the
• mean one standard deviation

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NDVI Over Time

• The trend of NDVI values as days from planting to
  sensing increases.

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Response Index
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Response Index

• Dr. Johnson
• Response to added fertilizer nitrogen
• RINDVI
• NDVI of the N-Rich Strip / Farmer Practice
• RIHarvest
• Yield of the N-Rich Strip / Farmer Practice

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RI Harvest and RI NDVI

• Relationship between the response index measured
  in season, (NDVI of fertilized
• plot / NDVI of check plot) from readings of
  cotton at growth stages from 60 to 80
• days after planting, and measured lint yield and
  the response index measured at
• harvest (yield of fertilized plot / yield of
  check plot) from all site years.

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Nitrogen Use and Uptake

• Research from different parts of the Cotton Belt
  suggests that high-yielding cotton crops contain
  about 50-55 lbs. N/bale
• (Basset et al., 1970 Mullins Burmester, 1990
  Unruh and Silvertooth, 1996).  Cotton Corp
• OSU Recommends 27 kg / bale (60 lbs N)
• Equivalent to .125 kg N / kg Lint, 12.5

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N Components

• If all plant components are accounted for in the
  algorithm, this results in 146.39 g N kg-1 lint
  (70.267 lbs N bale-1).
• Higher than the values recorded as optimum N
  rates for cotton grown in Oklahoma of 83.0 g N
  kg-1 lint. The
• Girma et al. (2007a) data closely fit the value
  of 90 g N kg-1 lint which was calculated from
  removal of lint and seed.
• Not known if using the N content of only the lint
  and seed is adequate
• Or if it will be necessary burs, leaves or stems.
  

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Nitrogen Use and Uptake

• Maximum N uptake occurred between 49 and 71 days
  after planting and was 2.9 and 4.3 kg ha-1 day-1
  for cotton receiving 84 and 168 kg N ha-1,
  respectively.
• Boquet, D.J., and G.A. Breitenbeck. 2000.
  Nitrogen rate effect on partitioning of nitrogen
  and dry matter by cotton. Crop. Sci., Vol 40 pg
  1685-1693
• Very little literature.
• NUE of 50.

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SBNRC Algorithm

• N Rate (YP0 RI YP0) N / NUE
• potential cotton lint yield, kg/ha 235.96 e
  2216.2 INSEY
• cotton lint yield, kg/ha 177.41 e 2216.2
  INSEY
• Where
• YP0 235.96 e 2216.2 INSEY
• RI 1.8579 RINDVI 0.932
• N 0.09
• NUE 0.50

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The Unknown

• Can Cotton Catch-up once it is behind?
• What should the level of preplant N be?
• What is the application window?
• Plant Growth Regulators.

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Thank you for your attention.
Any Questions??????
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The Answer to the Unknown

• Time..
• Time to see interactions over many environments.
• Time to increase the robustness of the YP model.
• Time to have set backs and learn from mistakes.

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• N Rate (YP0 RI YP0) N / NUE
• potential cotton lint yield, kg/ha 235.96 e
  2216.2 INSEY
• cotton lint yield, kg/ha 177.41 e 2216.2
  INSEY
• Where
• YP0 235.96 e 2216.2 INSEY
• RI 1.8579 RINDVI 0.932
• N 0.09
• NUE 0.50

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• Min .39 bale/ac185 lb/ac208 kg/ha
• Max 1.45 bale.ac695 lbs/ac781 kg/ha
• Approx 540 kg/ha 480 lbs 1 bale

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Tim C. Knowles, Jack Watson, and Vic Wakimoto
Late Season Nitrogen Fertilizer for Cotton.
Part of the 1999 Arizona Cotton Report, The
University of Arizona College of Agriculture

• Nitrogen (N) demand of a cotton crop starts out
  very low early in the season, begins to pick up
  starting at pin-head square, reaches a peak
  demand at peak bloom, and gradually declines as
  the crop approaches maturity. Nitrogen fertilizer
  must be available to the cotton plant in a timely
  fashion to meet crop demand. Split N
  applications coinciding with actual crop demand
  allow growers to apply adequate but not excessive
  amounts of fertilizer. A recommended window for N
  fertilizer application begins at the pinhead
  square growth stage and ends just prior to peak
  bloom.