Ground Drive - Calibration
Page
37
02/07
NOTE:
Some fertilisers run more freely
than others and actual usage may vary
from the first calibration sample taken. It is
recommended that the operator checks the
actual usage after the first bin load. It may
be necessary to perform a second
calibration test after some material has
been metered.
Method B:
Preferred method.
To be used when a more accurate
application rate is desired or rates that are
outside of the charts range of accuracy
(less
than
20kg/ha
or
higher
than
140kg/ha).
Step 1. Prepare seeder to take sample
from either the front, middle or
rear bin (refer steps 1 to 3 in
‘Method A’).
Step 2. Refer to page 56 to determine the
correct number of revolutions
required to simulate 1/20
th
of a
hectare
for
the
appropriate
seeding width in metres.
Step 3. Rotate the calibration handle the
correct number of turns for the
appropriate
seeding
width
collecting all of the material in the
sample box.
Step 4. Weigh the sample collected using
the scales supplied and multiply
that weight by 20. This figure will
be the actual application rate in
kg/ha.
Step 5. If the result is too low you will
need to increase the setting on the
variator. If too much material was
collected the reverse applies.
After making the adjustment you
will need to retest the system
following steps 4 and 5.
Example 1
An application rate of 60 kg/ha of
wheat is desired on a planting width of 10.0
metres using a 4 outlet meterbox with 3
meterwheels fitted. From page 56 we can
determine the required handle rotations
(38.5 turns) and page 42 the approximate
variator setting (3.5) for 3 meterwheels.
After setting the variator adjustment
lever to 3.5 and rotating the calibration
handle 38.5 turns we can weigh the
collected seed. For this example we find
we have a seed collection of:
Seed collected = 2.85 kg (2850 grams)
Therefore the actual sowing rate will
be 2.85 kg x 20 = 57 kg/ha.
It will be necessary to increase the
variator adjustment and retest the system to
obtain the desired 60 kg/ha.
Example 2
An application rate of 120 kg/ha of
urea is required on a planting width of 12
metres using 2 meterwheels in a 4 outlet
meterbox. From page 56 we can determine
the required handle rotations (32 turns) and
page 46 the approximate variator setting (6)
for 2 meterwheels using a high rate
sprocket ratio (refer page 63).
Fertilizer collected = 5.5kg (5500 grams)
Actual sowing rate = 5.5kg x 20 = 110kg/ha
Therefore increase the variator setting
slightly to obtain 120 kg/ha and retest.
To help in finding the new setting, use
the following example.
Desired rate x variator setting
Actual collected rate = new setting
120kg/ha x 6
110kg/ha
= 6.55 variator setting
Therefore increase the variator setting
from 6 to 6.5 to obtain 120 kg/ha and retest.
