Soil Type Hemp will grow well in most good soils that
are suitable for crops.
Acidic soils however, will result in reduced
yield.
Poorly drained or
sandy soils should be avoided.
 
Seed Bed Preparation
 
If soil is below pH6 apply lime before
primary cultivation.
A fine weed-free seedbed with minimum
compaction is essential for good establishment.
 
Fertiliser Nitrogen: Recommended N levels are currently 80kg/ha prior to sowing or applied with the seed, plus an additional 80kg/ha should be applied as a top dressing when the crop has five pairs of true leaves.
Phosphorus and potassium: Recommended levels are currently 160kg/ha of P2O3 and 80kg/ha K2O. Do not over apply potassium as this encourages changes to cannabinoid levels. If organic manures are used this must be taken into account and reduced levels of fertiliser should be applied.
Drilling Drill early to late October to early November

Soil temperature should be consistently
above 10° C. Drilling time
will influence fibre yield; earlier sown
crops will obtain higher yields.
Drill with rows 12.5–25 cm apart (5–10”), at
a depth of 3 cm (1”).
Recommended seed rate is 48kg/ha (300
seeds/m2).
 

Weed control Hemp plants are very competitive against
weeds and once established will outgrow and smother other plants through the
development of a tall dense canopy.
Manual weed control is therefore only
required during establishment.
 
Pests and Disease So far diseases have not caused a major a
problem due to the small scale cultivation, but care will be required as
areas of production increases. Rusts may become apparent with increased
cultivation
area.
Botrytis cinera (grey mould) and
Sclerotinina sclerotionim (white mould) are common on industrial hemp. The
moulds lead to lesions on the stem where no fibre is laid down. This can
cause stem
breakage during processing.
 It is
not recommended to sow hemp
following oil seed rape due to disease carry
over.
 
Retting Retting is the fungal breakdown of straw to
release the fibres from the woody core. Dew retting is the traditional method
and occurs after desiccation when the crop is swathed and left to rett on the
ground.
The crop should be turned at least once to
allow for even retting. All swathers (and rakes) must be set at the correct
level and care must be taken to avoid raking stones into the fibre crop. Dew
retting will take
about 10 – 20 days. But the time taken will
depend on weather conditions.
Stand retting is an alternative method
currently being researched. The crop is desiccated with a herbicide while
still standing.
However, because of the height of the hemp
there are problems with this
method and it is not currently
recommended.
 
Cutting/harvesting Time
of harvest is usually between mid March to mid May (southern hemisphere).
The
exact date will depend on the time of sowing, the variety grown and the
weather conditions for the growing season.
Specialist
equipment
has been manufactured for harvesting.
Twin
drum mowers are recommended for dew and stand retted crops.
Triple
drum mowers and mower-conditioners are unsuitable.
 
Baling The
straw must be dry when baled (max moisture content 18%) and
kept
undercover in storage. Crop will be rejected by processors if the
moisture
content is too high and the crop will spoil.
composite
materials.
 
Processing Industrial processors mechanically
remove the fibres from the shive
(the woody core). The fibres are
then used for a variety of products
ranging from insulation, soil
stabilisation matting and plastic
 

Note: The
recommendations made in this document are for guidance purposes only. All crops
are subject to seasonal variation and results are based on knowledge currently
available and 3 years of field trials. The trade names mentioned are products
that have been used in this project but other equally suitable products are
available. Whilst every effort has been made to offer accurate advice Hemptons
accepts no liability for information provided in this document.

Amelia
amelia.karg@hemptons.co.za

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