Agriculture Reference
In-Depth Information
Table 21.3. The environmental impact arising from the production of 1 ha of hemp compared to seven
other annual crops in France.
Impact
category
Unit
Hemp
Sunflower
Rape
Peas
Wheat
Maize
Potato
Sugarbeet
Eutrophication kg
20.5
20.2
20.6
34.4
21.9
21.0
23.8
24.1
eq-PO 4
Climate
change
kg
2,330
2,300
2,700
2,890
3,370
3,280
4,120
4,900
eq-CO 2
Acidification
kg
9.8
10.8
12.8
8.3
16.3
13.6
22.4
24.5
eq-SO 2
Land pollution kg
2.3
1.8
2.5
0.1
4.0
3.0
4.9
6.7
eq-1,4-
DCB
Energy use
MJ
11,400
11,900
13,800
11,800
18,100
23,000
25,600
26,300
Land surface
used
m 2 /year
10,200
10,000
10,000
10,500
10,200
10,100
10,400
10,200
Note : kg eq = kg equivalent.
hemp, peas and sunflower (11,400-11,900
MJ) and high for maize, potato and sugarbeet
(23,000-26,300). The difference between the
amount of land under cultivation for each crop
is negligible.
For all the impact categories (with the
exception of land area used), the impact is invar-
iably low for hemp and sunflower and invariably
high for potato and sugarbeet. For rape and
peas, the impact is relatively low and for wheat
and maize, the impact is intermediary.
impact, they exhibit little difference in terms of
the relative contributions of the materials and
resources to the impacts.
The effect of alternative scenarios
on hemp production
In certain areas, organic fertilizers are available
at very low cost and their use can reduce pro-
duction costs dramatically. The substitution of
a mineral fertilizer with pig slurry reduces the
climate change impact by -24% and energy
use by -32%, but increases eutrophication
(+16%), acidification (+140%) and terrestrial
pollution (+1720%) (see Table 21.5). No-till
farming is interesting because it reduces ero-
sion, production costs and hours of work
required. No-till farming reduces the climate
change impact (-6%), acidification (-13%) and
energy use (-16%).
The amount of nitrate washed out will be
lower where the nitrate residue in the ground at
the time of harvesting is low and when the period
between harvesting and planting of the following
crop is short. A reduction in washout of 40-20
kg N/ha reduces eutrophication (-43%) and cli-
mate change (-10%) (Table 21.5).
Contribution made by the substances
produced and resources used
The contributions to the different environmen-
tal impact categories of the substances pro-
duced and the resources used have been
evaluated for hemp (characterized by low read-
ings), wheat (intermediary readings) and sugar-
beet (high readings) (Table 21.4). For these
three crops, eutrophication is due primarily to
NO 3 (75-89%). Climatic change is due mainly
to N 2 O (56-59%) and to CO 2 (40-43%).
Acidification is due to NH 3 , SO 2 and NO 2 emis-
sions and the three crops contribute compara-
ble amounts. Terrestrial ecotoxicity arises
mainly from Ni (66-70%) and Cd (26-29%) in
the ground. Energy use is accounted for mainly
by the use of crude oil (44-46%) and natural
gas (32-36%).
Even though these three crops show dif-
fering input requirements and differing levels of
21.2.4 Discussion
This study has compared the potential environ-
mental impact of hemp with that of seven
 
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