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linked to the GPS points to generate maps of
the geographical spread of the plant nutrients
available in the soil. Imbalances are then cor-
rected differentially across the field according
to the need of each square in the field (usually
20 m x 20 m).
This is a very popular starting point for preci-
sion farming,
probably because the service is
freely available from various service providers
and is well marketed. It also provides a rapid
return on the investment because it directly
addresses plant nutrition, which strongly corre-
lates to crop performance.
Pedological and physical soil properties
Pedology involves the study of the origin and
classification of soils. The morphology of
soil types differs geographically over short
distances in fields and these differences affect
vegetation and crop performance directly.
Information like water retention capacity,
drainage, the incidence of shallow water
tables, leaching of plant nutrients, natural
fertility, texture, structure, compactability,
stoniness and tillability is fed into a GIS so that
further calculations can be carried out with
the data. During soil surveys the relevant soil
properties are identified and recorded by a
soil scientist with the aid of soil drills at GPS
points. Soil maps are then generated with GIS,
indicating the soil types as soil bodies on the
farm. These soil properties are interpreted by
the soil scientist to indicate areas with different
potentials and applications in the fields. These
maps are then processed further with the aid
of GIS to user maps that can be loaded on the
tractor’s precision screen to adjust the applica-
tion of seed and plant nutrients to the capacity
of the field.
This is a quite
complicated facet of precision
farming that requires advanced and rela-
tively expensive equipment on the tractor
and implement. Some producers do start
their foray into precision farming with this
technology.
Precision soil cultivation
Soil compaction and water infiltration are two
major aspects of successful grain production.
Controlled track traffic and the effective man-
agement of soil cultivation systems with the
aid of GPS technology and automatic steering
systems unlock possibilities for effectively
managing soil compaction. The degree and
depth of soil compaction is measured with a
penetrometer. This data enables you to exactly
determine the required depth of soil cultiva-
tion. The method of breaking up soil compac-
tion must be adjusted to the entire production
system so that the crop is always established
in soil that is sufficiently loose within the
norms. The ideal is also for the soil not to be
compacted again where you intend plant-
ing in future. Track traffic can be successfully
controlled over a number of years with the aid
of GPS technology and automatic steering sys-
tems. In this system the entire field is properly
loosened, but preferably not the tractor tracks.
All the implements that will be required in the
course of the season are adapted to follow
these tracks and work only as widely as the
planter, or multiples thereof.
The main benefits of this system are that:
1. Aggressively deep tillage is eliminated or
drastically reduced.
2. The crop is always located in uncompacted
soil.
3. Water infiltration is promoted.
4. There is a possibility of enriching the zones
that are planted regularly with plant
nutrients.
5. Mechanisation costs are significantly
reduced.
6. This is also the ideal system to combine with
minimum tillage and no-till.
Most new tractors of more than 120 kW have
GPS technology as standard issue, which
paves the way for driving precisely, cultivat-
ing precisely and planting in exactly the right
place. Farming systems should be adapted to
utilise this technology for optimum production
and
it is a logical point of departure when a
new tractor is purchased.
Other techniques
Technology is also available to make more
accurate top dressing possible. Advanced
sensors on implements using measurements of
the chlorophyll activity (green colour spectrum
53
GRAANGIDS
2017
GRAIN GUIDE
Continued on p. 55