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41
GRAANGIDS
2016
GRAIN GUIDE
variety of soils like the Valsrivier, Sepane,
Oakleaf and Tukulu soils, which are
regarded as marginal for crop farming due
to the lower infiltration ability, higher run-off
and high evaporation losses.
These soils are mainly used to plant
sunflower and grain sorghum, and mulch
tillage with winged tine implements provides
good results. Primary tillage of 200 mm
or shallower with a chisel plough is mostly
adequate.
4. Soils with more than 25% clay in
the topsoil
This group, comprising vertic or melanic
soils, mainly has a dark colour and an
organic carbon content that varies between
0,5% and 4%, with a well-developed
structure in the topsoil. Soil types include
(but are not limited to) the Arcadia,
Rensburg, Bonheim and Inhoek soil
structures.
These soils are quite resistant to wind and
water erosion and are excellently suited to
no-till practices. However, these soils are
regarded as marginal for dryland crop
farming in the long term.
Summer rainfall of between 550 mm and
700 mm per year
1. Red and yellow well-drained sandy
soils with less than 20% clay in the
topsoil
The main soil types in this group include
the Hutton, Clovelly and Avalon soils and
are suitable for growing most crops. Soil
acidification is the biggest problem with
these soils and regular liming is essential.
Both conventional and mulch tillage
practices are recommended for these soils.
When mulch tillage is used in sandy soils
with less than 10% clay in the topsoil, a
deep ripper action combined with controlled
track traffic is recommended. Crop rotation
is also essential to retain the biological soil
quality.
2. Yellow and grey soils with plinthic
and gley subsoils
The soils in this group (e.g. the Westleigh,
Pinedene, Longlands and Kroonstad soils)
are characterised by wet subsoil during
periods of high rainfall. In dry years they
can deliver good crops, while they tend to
become waterlogged during wet periods.
The wet soil conditions make it difficult to
control weeds, while self-sowing and soil
acidification are also a significant problem.
Valsrivier and Sepane
Arcadia and Rensburg
Westleigh and Pinedene
Avalon
Continued on p. 44