1. Evaluation of the Yield Potential Based NFOA for Cotton
D. Brian Arnall
Oklahoma State University
W. Raun, J. Solie, M. Stone, R. Taylor, J.C. Banks O. Walsh, D. Edmonds, C. Daft, B. England, Y. Kanke, B. Desta

2. 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

3. 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

4. Yield Potential Model Why use YP. Using NDVI as a function of GDD.
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

5. Yield Potential Model Winter Wheat
Units: biomass, kg/ha/day, where GDD>0

6. INSEY DFP
Relationship between in season estimate of yield (INSEY) computed from NDVI
readings of cotton collected between 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.

7. 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 (
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

8. NDVI Over Time
The trend of NDVI values as days from planting to sensing increases.

9. 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

10. 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.

11. Nitrogen Use and Uptake
Research from different parts of the Cotton Belt suggests that high-yielding cotton crops contain about 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%

12. N Components
If all plant components are accounted for in the algorithm, this results in g N kg-1 lint ( 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.

13. 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 Nitrogen rate effect on partitioning of nitrogen and dry matter by cotton. Crop. Sci., Vol 40 pg
Very little literature.
NUE of 50%.

14. SBNRC Algorithm N Rate = (YP0 * RI – YP0) * %N / NUE
potential cotton lint yield, kg/ha = e * INSEY
cotton lint yield, kg/ha = e * INSEY
Where:
YP0 = e * INSEY
RI = * RINDVI – 0.932
%N = 0.09
NUE = 0.50

16. 2008 Sensing

17. 2008 Sensing

18. 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.

19. Thank you
Any Questions??????