Agriculture Reference
In-Depth Information
13
12
11
10
9
8
7
6
5
4
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
Year
control
100 kg/ha
200 kg/ha
average yield
of monoculture
300 kg/ha
average yield for the
department
Fig. 5.16.
Hurd yield as a function of potassium fertilization over an 11-year trial period conducted in
L'Eure. The effect on yield of monoculture is compared to the average yield for the department (Chambre
d'Agriculture de l'Eure, 1989).
These results indicate that fibre processing is
easiest with a seeding rate of 40 kg/ha.
hemp fibre is currently being undertaken by
Brigitte Chabbert's research team at INRA in
Reims. The preliminary results of this study are
presented in Chapter 3 of this topic.
Influence of the harvest date
Early harvest makes for more difficult fibre separa-
tion. This is especially true if the plant is not retted.
When harvest is undertaken late, differences in the
ease of fibre separation are less marked.
5.4.10
Soil type and its effect on yield
The theoretical potential of the crop is important
and is of the order of 14 t of dry matter (DM)/ha.
In some situations, the yield has been as much as
20 t/ha. Table 5.6 presents yield against soil type
observed in trials in de l'Aube. The nitrogen appli-
cation corresponds with the recommended levels
for the area and is based on empirical practice
rather than the results of a scientific study.
Influence of the variety
The influence of hemp variety on fibre separa-
tion is relatively small, although further in-
depth studies on this subject need to be
undertaken. Some advantage does appear to
have been demonstrated for the F17 variety
and a slight disadvantage for S27.
5.5 Crop Protection
5.4.9 Influence of crop cultivation
factors on the morphology and
biochemistry of fibres
5.5.1 Treatment of the seed stock
Until 2002, a single seed treatment had been
used by the FNPC. In this experiment, how-
ever, ten preparations were tested (Table 5.7).
A study of the influence of harvest date on the
anatomical and biochemical properties of
