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49
GRAANGIDS
2016
GRAIN GUIDE
Convert from conventional farming
to
PRECISION FARMING
Precision farming involves the area-specific
adaptation of production techniques on the
basis of geographical data on the chemical,
physical and morphological soil properties,
but also other geographical production data
like yield data and growth indices gathered
through remote sensing. The ultimate aim is
to run the farm in a sustainable manner. But
where do you start?
Conversion to precision farming does not
necessarily have a specific starting point and
course, but all the methods have the gather-
ing of geographically linked data that affects
production in common. The availability and
cost of geographical data and equipment on
implements usually play a significant role at
the start of the conversion.
Yield data
Yield data is gathered by yield monitors in
combine harvesters. As the combine harvester
drives across the field and harvests, the yield
is continuously determined and captured at
global positioning system (GPS) points. After
the data has been processed, yield maps of
the fields are generated and the areas where
the crop yield was higher and lower are clear-
ly indicated. The lower yield areas are then
investigated to determine the possible causes
of the reduced yield. Production practices are
then adjusted to eliminate the yield-reducing
factors in these areas so that the whole field
can yield according to its potential.
If the combine harvester is equipped with a
yield monitor, it can be employed for preci-
sion farming and this is a meaningful starting
point. However, the data must be processed to
meaningful interpretable yield maps.
Growth indices
Remote sensing with the aid of satellite im-
ages, images from manned aeroplanes and
unmanned aeroplanes (drones) are increas-
ingly used to obtain digital images of fields.
Images are usually taken in serial format
during the growing season. These are then
processed electronically to produce, among
other things, growth indices (NDVI) throughout
the growing season. Areas with differences
in the relative crop growth are indicated in
different colours in this specific application, so
that areas where the crop growth is lower can
be identified. The lower-yielding areas can
be visited with the aid of a GPS and studied
to identify the possible causes of poorer crop
growth during the season. Growth indices are
a relatively affordable but also easy starting
point because the data is processed by the
supplier of the service to a final product.
Chemical soil properties
The geographical spread of chemical soil
properties is done by way of grid sampling.
Soil samples are taken at GPS points identified
in a grid pattern on the field. The soil sample
for each GPS point is packaged separately
and analysed by a laboratory. The raw data
is linked to the GPS points by the service pro-
vider to generate maps of the geographical
spread of the plant nutrients available in the
soil. Imbalances are then corrected differen-
tially 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 cor-
relates to crop performance.
Pedological and physical soil properties
Pedology involves the study of soil types. The
morphology of soil types differs over short
distances in fields and these differences affect
vegetation and crop performance directly. Ex-
amples of these are water retention capacity,
drainage, the incidence of shallow water
tables, leaching of plant nutrients, natural
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