Main box seed rate calibration – Great Plains 800 Material Rate User Manual
Page 7
Great Plains Manufacturing, Inc.
Main Box Seed Rate
5
2011-10-25
175-057B
Main Box Seed Rate Calibration
Differences will exist between the tested seed and field
conditions used to generate the Seed Rate Charts, and
your seed and conditions. To accurately achieve your
target population, Great Plains recommends calibrating.
Perform the calibration with opener frames lowered (if
the openers are raised, the clutch disengages). 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 three
(3) light weight containers, each capable of holding a
row’s sample. Weight the empty container(s).
3.
Disengage the lock-out hub (see Operator manual),
to permit independent rotation of the main jackshaft.
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.
Place the hex socket of the crank on the left end of
the main jackshaft.
6.
Pull the seed hoses off the top of three opener seed
tubes, at the top of the openers. Place the hoses into
each sample container.
Figure 6
Calibration Crank Stored
28067
Example: You want to apply barley at 64 pounds per
acre with your 7
1
⁄
2
inch drill. RateSample is:
Example: the 7
1
⁄
2
inch drill has 12 rows.
SamplePerRow is:
Example: 3 rows are to be used in the sampling:
The ExpectedSample weight is 1.6 lb.
Example containers: 3 each weighing 0.5 lb
or 1.5 lb total
6.4
64
10
------
=
0.53
6.4
12
--------
=
1.60
0.53
3
×
=
RateSample
FieldRate
10
----------------------------
=
SamplePerRow
RateSample
RowCount
------------------------------------
=
ExpectedSample
SamplePerRow
SampledRows
×
=
Figure 7
Calibration Crank Engaged
28068