Agriculture Reference
In-Depth Information
it must be dried and cleaned as quickly as pos-
sible. Ideally, drying should be started within a
few hours of harvesting. Where producers are
a long distance from the drying silos, the con-
tainers can be ventilated via a perforated base,
which can help prevent overheating. The dri-
ers are modified, again with the objective of
avoiding unnecessary shocks, by placing rub-
ber bibs for the hemp seed to fall on. The dry-
ing temperature is extremely important; the
seeds must not be allowed to reach a tempera-
ture above 40°C.
Particular mention must be made of those
farmers undertaking drying on the farm. If an
air-heating device is used together with an aer-
ating/ventilating device, it is essential that the
gas produced by the hot air generator does not
contact the drying seed. Hemp seed is easily
impregnated with combustion smells and this is
likely to render it unsaleable.
Under these conditions, hemp seed can pre-
serve its qualities and will make a first rate raw
material for oil extraction or dehulling for incor-
poration into energy bars, chocolate or cakes.
Hemp seed can be stored when its humid-
ity is at 8%. Commercial standards stipulate
9%, but experience suggests that there is still a
risk of deterioration at this level.
The method of storage, especially if this is
undertaken at the farm, must pay due attention
to the attraction hemp seed represents to birds
and rodents. Conditioning in big bags on pal-
ette boards and protection from rodents by rat
bait may be a suitable answer.
generates projectile material and tarpaulins
must be used around the blades in order to pro-
tect the users. These tarpaulins, while neces-
sary for health and safety reasons, can get in
the way of cutting hemp due to the unusual
height of this crop.
Knife mower or section mowers.
Consequently,
cutting blades are the best adapted for mowing
hemp. They have the advantage of producing
a clean cut, release the material quickly and
achieve a high reaping speed (between 15 and
20 km/h) with a working width of 2.4 m.
The system of blades most commonly
used in France is the double knife Busatis-bidus
system (Fig. 6.4). This allows reaping to be
conducted within a few centimetres of the
ground, leaving the earth clean while harvest-
ing the maximum amount of hurds.
Unfortunately, the weak point of this sys-
tem is the need to sharpen the blades frequently
in order to maintain optimal performance. The
time between sharpening depends on the height
of cutting and the presence of dead stalks or
stones in the field. Depending on the conditions
of work, a newly sharpened set of blades can cut
between 1.5 and 15 ha efficiently.
In order to satisfy the demands of pro-
ducers working a non-combined system (no
hemp seed harvested) with plants growing to
4 m in height (late flowering varieties with no
cutting of the tops by a combine harvester),
some manufacturers market mowers with
two, three or even four cutting heights (Figs
6.5 and 6.6).
Hurd harvesting
MOWING
.
As the crop matures, the lignin con-
tent of the fibres increases and the stems
become increasingly difficult to cut. In the past,
the stems were pulled up with their roots, a
harvesting method that is still used for flax.
Today, the majority of reaping machines
placed on the market by manufacturers are
disc mowers. These perform well when har-
vesting fodder as their forward speed is not
limited in the way that it is for section mowers.
That said, the impact cutting technology is not
adapted to hemp harvesting. The discs are
made for cutting fine fluid material such as hay
and straw, which must not clog up and block
their rotation. Furthermore, this sort of cut
Fig. 6.4.
Double knife-cutting system (Busatis, ITC©).
