Agriculture Reference
In-Depth Information
9.6
Treatment of Hemp Seed
This gives rise to two basic common-sense
rules that should be respected. Harvesting
should take place when:
the highest leaves start to turn yellow;
The harvesting of hemp seed by combine
harvester yields a mixture of dry, ripe seeds,
together with seeds that are only partially
ripe or even completely green. Additionally,
this material can also contain bits of leaf
material and pieces of greenery from the
inflorescence. The humidity levels observed
are 20%. This is one of the reasons farmers
are asked not to harvest until humidity levels
are below this level.
It is well known that the more green mater-
ial the harvested crop contains, the higher the
risk of overheating, which itself is accompanied
by risks to the material. Hemp, as with other
oil-rich seeds, is very sensitive to hydrolysis and
oxidation of fatty acids. It is therefore neces-
sary for the drying process to be undertaken
quickly.
Second requirement: dry slowly!
In order to produce a marketable prod-
uct, the hygrometry level must be reduced
to 9%.
Given the quantity of material processed,
this can be achieved only in silos of a sufficient
capacity and equipped with driers. The seeds
should have first been sorted and aired in order
to remove all non-ripe seeds.
Drying is undertaken over a relatively
long period in order to avoid damaging the
product. The drying temperature must not
exceed 40°C.
Finally, given the friable nature of the
outer integument, new impurities can appear
during the treatment process. There is there-
fore a need for another cleaning, by aspiration,
before the seed can then be stored.
The store itself must be well aired and
monitored carefully.
•
•
the seeds at the base of the inflorescence
are ready to fall off on 75-80% of plants.
In terms of the harvesting equipment, combine
harvesters with axial fan blades are used at a
moderate rotational speed (
∼
300 turns/min).
9.6.2
Installations and costs
In France, all the hemp seed collected and des-
tined for sale transits through the silos of com-
panies that store cereals. Only they have the
capacity to deal with and store 4000-5000 t
of seed/year.
Taking into account that which was explained
above, the costs of drying, based on figures from
January 2005, are of the order of €15-18/t.
9.7
Industrial Costs: Investment
and Running Costs
The informed reader will understand readily that it
is not easy within this text to provide definitive and
intangible values for investment and production
costs. Much depends on the degree of sophistica-
tion of the installation, its size, volume of material
processed, rate of throughput and the nature of
the end product (degree of refinement). An attempt
will be made to present and apply a methodology
and to produce a rough estimate for an industrial
set-up and its equipment destined for the produc-
tion of fibre and the conditioning of hurds.
9.7.1 Investments
9.6.1 Harvesting
The cost of the fibre extraction production line
is strictly a function of the hourly volumes that
one aims to process. The following rough esti-
mates are provided.
Theoretical production: 1.5 t/h (equiva-
lent to 4000-6000 t of straw/year).
The nova-Institut estimates an investment
required at more than
Farmers eager to harvest hemp seed must
ensure that it is ripe. This sounds obvious, but
it must be emphasized every year to over-hasty
farmers.
This is not as simple as it may sound, how-
ever: a stand of hemp does not mature evenly.
Additionally, the lower seeds reach maturity
before those higher up the plant.
3,000,000 (based on 2005
figures) simply for fibre extraction. Others estimate
a figure of €5 million for a capacity of 5 t/h.
€
