Great Plains 800 Material Rate - Manual (Page 37)

Great Plains Manufacturing, Inc. Table of Contents Main Box Rates Fertilizer Rate 35
2011-10-25 Table of Contents Main Box Rates 175-057B
Fertilizer Rate Calibration
Differences will exist between the tested fertilizer and
field conditions used to generate the Rate Chart, and
your fertilizer and conditions. To accurately achieve your
target application, Great Plains recommends calibrating.
Perform the calibration with the opener frames lowered
(if the openers are raised, the clutch disengaged). Leave
the tractor hitched for movement control.
Due to the large number of crank revolutions per acre
(728) and per hectare (1799), a practical calibration
would be a simulation of
1 ⁄
10
th
acre or
1 ⁄
10
th
hectare.
1. Estimate the sample sizes.
2. To perform this calibration, you need a scale that is
accurate near the aggregate sample size, and 3 light
weight containers, each capable of holding a row’s
sample.
3. Disengage the lock-out hub (see Operator manual),
to permit independent rotation of the main jackshaft.
Refer to Figure 13
4.
Remove the calibration crank from its storage stob
on the left top side of the main tool bar. Store the
retaining pin on the stob.
Refer to Figure 14
5.
Place the hex socket of the crank on the left end of
the main jackshaft.
6. Pull the fertilizer hoses off the top of three openers,
at the top of the openers. Place the hoses into each
sample container.
7. If not already done, make any density correction,
then using the chart for the target rate, set rate
adjuster. If seed is loaded, remove the drive chain for
the seed box (unless you are simultaneously
calibrating seed rate).
8. Load fertilizer above the rows to be sampled. Load
well more than the expected sample size.
Possible Agricultural Chemical Hazard:
Follow material supplier recommendations for safety
precautions in handling fertilizer.
Figure 13
Calibration Crank Stored
28067
Example: You want to apply 109 pounds per acre
with your 12-row 7
1 ⁄
2
inch drill.
Example: the drill has 12 rows:
Example: 3 rows are to be used in the sampling:
The expected sample weight is 2.73 lb.
Example: 3 containers each weighing 0.5 lb
or 1.5 lb total
10.9
109
10
---------
=
0.91
10.9
12
----------- =
2.73 0.91 3 × =
RateSample
FieldRate
10
----------------------------
=
SamplePerRow
RateSample
RowCount
------------------------------------
=
ExpectedSample SamplePerRow SampledRows × =
Figure 14
Calibration Crank Engaged
28068
See example on page 34, which determined an initial
rate adjuster setting of:
60