“The main objective is to control
lice in order to keep viruses at bay,
and to prevent early or late rust
caused by fungi,” Botes explains.
Fertilisation includes the
macronutrients nitrogen,
phosphorus and potassium,
as well as zinc. Bruwer also
adds plenty of calcium for
tuber development.
HARVESTING
In this region, the foliage of the
potato plant will usually die off
due to frost during the first half of
May. The plants are thereafter left
for approximately a month before
being harvested. If the frost does
not arrive in time, as happened
this season, Bruwer covers the
plant with soil to kill it off, which
in turn enables the potato skin to
set. This is particularly the case
for Lanorma, which requires
a month for proper skin set.
“Many farmers remove the
potatoes a week after they’ve
covered the plant, but at that stage
the skin hasn’t set yet,” he says.
Harvesting is carried out
mechanically with a Grimme
GT170 potato harvester, and
if the quality is good, the
Bruwers can harvest and sort
about 3ha/day. The packhouse
operates a number of lines to
cater for seed potatoes and
various grades of table potatoes,
which Bruwer sells under two
separate brands at fresh produce
markets across South Africa.
The packhouse is used
specifically for the potatoes
and therefore operates for only
three months of the year. It also
houses a cold storage area where
the seed potato stock is kept.
“It’s important to store potato
seed in cool conditions because
the potato then goes into
dormancy. If you harvest it and
leave it standing in a shed, the
potatoes start sprouting within
a month,” explains Botes.IRRIG ATI ON
Bruwer utilises a pivot irrigation
system that draws water from the
Orange-Vaal water system. Water
rights are allocated on a per
hectare quota basis, and he does
his crop planning in line with
what he terms the “crop factor”.
Potatoes use water at a rate
of 5 100cm³/ha per season,
similar to sunflower (about
5 000cm³/ha). Lucerne, by
comparison, has a water usage
of about 10 000cm³/ ha, which
means that twice as many
potato or sunflower hectares
can be planted as lucerne.
Cropping is planned to make
maximum use of every drop
of allocated water, and Bruwer
stresses that he has to pay tax
on his entire quota, regardless
of whether all of it is used.
He further optimises water
usage through neutron moisture
meters, which are underground
probes that measure soil waterCrops Potatoes
TOP LEF T:
Gerhard Bruwer
looks in on the
harvesting process.TOP RIGHT:
Bruwer holds
up one of the
bags in which his
premium-quality
table potatoes
are packaged
for sale at fresh
produce markets
countrywide.ABOVE:
Certified seed
potatoes are stored
in a coldroom
to enable them
to go dormant.
This ensures that
they do not start
sprouting prior to
being delivered
to commercial
farmers, who
will then plant
them to produce
table potatoes.content by detecting neutrons
and thereby water molecules.
“We also do physical profiling
twice weekly to see what the soil
water profile looks like, in case
the probe isn’t entirely accurate.
This is to ensure we give exactly
the right amount of water.”
Other precision practices include
soil sample analysis and leaf sap
analysis to check for trace element
deficiencies. Consultants are
also called in when required.
Bruwer carries out variable
irrigation and variable application
of fertiliser and chemicals on a per
block or per land basis, but is not
yet at the point of implementing it
at individual plant level. However,
he says that Genade Boerdery
will “definitely” use this level of
precision at some stage in the future.- Phone Gerhard Bruwer on
082 878 5422, or email him at admin@
genadeboerdery.co.za. Phone Johann
Botes on 082 865 7813, or email him
at [email protected].
▪
FW42 farmer’sweekly 2 August 2019