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1996
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Chad Dow, Dr. Jim Schaffer, and Dr. Marvin Stone inspect the variable
rate N applicator prior to the field day in March, 1996
In, March, 1996, our first variable rate N applicator was demonstrated
to the public at a field day in Hennessey, OK. Over 100 people (farmers,
dealers, industry, extension, & others) were in attendance.
 In
both wheat and bermudagrass experiments, Hasil Sembiring looked for indices
were we could detect differences in N and P, independent of one another.
For wheat, numerator wavelengths between 705 and 735, and denominator
wavelengths between 505 and 545 proved to be reliable predictors of N
and P uptake. In bermudagrass, the index 6951405 proved to be reproducible
from one season to the next. Readings at 435 nm were independent of N
and P treatment and later found to be useful as a covariate.
In 1996, we initiated two trials that aimed to show how small-scale management
of applied N could result in increased wheat grain yields. A refined algorithm
for applied N based on predicted yield potential and a response index
had not yet been developed, thus results were inconclusive.
 Dr.
Jim Baird and Dr. Marvin Stone inspect the turf areas that had received
variable N applications using the JD 1800.
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Soil
Fertility students sense and collect turf samples (biomass). The realtionship
between total forage N uptake and NDVI was used to apply variable N rates
in turf.