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35
GRAANGIDS
2017
GRAIN GUIDE
Calibrate your planter correctly
Successful cropping has developed into a highly specialised process. Planters play an extremely
important role in the process –
particularly with respect to the accurate spacing of plants and
the plant depth of seed. The accurate dispensing of fertiliser is also important.
The function of a planter
A planter has the following basic functions:
• It opens the fertiliser furrow up to the correct depth for fertiliser placement.
• Correct measuring of calibrated fertiliser and placement.
• It opens the seed furrow up to the correct depth for seed placement.
• Correct measuring and placement of seed.
• Closing of seed and fertiliser furrows.
• Compaction of the soil for effective soil to seed contact.
The above functions must all take place simultaneously and their effectiveness should not be
speed sensitive.
Seed dispensing
The primary function of planters is to dispense seed correctly. Seed can be dispensed in the
following ways:
• Conventional horizontal tray dispenser.
• Tray dispenser dispensing at an angle.
• The finger-wheel dispenser.
• The vacuum tray dispenser.
Tray dispensers are still used, but because seed grading is no longer that accurate, vacuum
dispensers and finger-wheel dispensers are used increasingly.
Dispensing and placement of fertiliser
Fertiliser is dispensed as granules or in liquid form. Granular fertiliser is dispensed positively
with a star-wheel or worm dispenser.
Liquid fertiliser is dispensed with a squeeze pump, or – these days – with a special liquid ferti-
liser pump.
Calibration of the planter
When a planter is calibrated, wheel slippage of the planter drive wheels is an important compo-
nent to take into account.
It is important to calibrate the planter in the field to be planted to compensate for wheel slip-
page. Different soils will cause different wheel slip percentages.
4.1. Calibration of fertiliser
Fertiliser dispensing can be calibrated as follows:
• Mark out a distance of 10 m in the field.
• Catch the fertiliser from one of the fertiliser delivery tubes in a suitable container across
the 10 m distance, while the planter moves at a normal working speed.
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Continued on p. 36