Agriculture Reference
In-Depth Information
Table 21.2.
Inputs, yield and emissions of N in the form of nitrate (all in kg/ha) for three different
scenarios for hemp production in France.
Pig slurry
No-till
Reduced washout
Inputs
Pig slurry
20,000
N (ammonium nitrate)
0
75
75
P
2
O
5
(triple superphosphate)
0
38
38
K
2
O (potassium chlorate)
51
113
113
CaO
333
333
333
Seed
55
55
55
Pesticide (active ingredient)
0
0
0
Diesel
72
39
65
Agricultural machinery
18.8
11.6
16.4
Straw yield dry matter
6,720
6,720
6,720
Followed by an intermediate crop (%)
a
0
0
0
Following crop
Wheat
Wheat
Wheat
NO
3
-N emitted
40
40
20
Note
:
a
Indicates the percentage of cases in which we believe an intermediary crop was sown between the harvesting of
the crop and the sowing of the following crop.
and sourcing of key inputs (agricultural machin-
ery, diesel, fertilizer, pesticides and seeds) have
been taken into consideration using the method
proposed by Nemecek and Heil (2001). The
data for energy contributions and transport are
derived from the BUWAL 250 database
(BUWAL, 1996). Buildings have not been
included as their contribution to the impact of
annual crops is negligible: 0-2% (van Zeijts and
Reus, 1996).
For all the crops, we have assumed that
good agricultural practice has been followed
(
Bonnes Pratiques Agricoles
- BPA); that is to
say, reasonable fertilization and integrated crop
protection. For hemp, a straw yield of 8000
kg/ha with 16% humidity has been used. For
the other crops, an average yield for the period
1996-2000 (AGRESTE, 2001; FAO, 2004)
has been used. Details of the calculations of the
field emissions are available from van der Werf
(2004).
to 220 (sugarbeet) kg/ha of N; from 32 (sun-
flower) to 101 (sugarbeet) kg/ha of P
2
O
5
; from
0 (hemp) to 5.5 (potato) kg/ha for the active
pesticide ingredient; and from 65 (hemp) to
165 (potato) kg/ha for diesel. Hemp and sun-
flower can be characterized as crops requiring
little input, whereas potatoes and sugarbeet
can be described as crops requiring a high
input.
The impact is variable (Table 21.3).
Differences are lowest for land use (10,000-
10,500) and most significant for terrestrial
ecotoxicity where the range is 0.1-6.7. For cli-
mate change (2300-4900), acidification (8.3-
24.5) and energy use (11,400-26,300), there
is a fairly sizeable variation between crops,
whereas for eutrophication (20.2-34.4) this is
modest.
Eutrophication is low (approximately 20
kg eq-PO
4
) for hemp, sunflower and rape, but
high (34kg eq-PO
4
) for peas (Table 21.3). The
impact on climate change is low for hemp and
sunflower (2300 kg eq-CO
2
) but high for potato
(4120) and sugarbeet (4900). Acidification is
low for peas, hemp and sunflower (8-11 kg
eq-SO
2
) and high for potato and sugarbeet
(22-25). Terrestrial ecotoxicity is very low for
peas (0.1 kg eq-1,4-DCB), low for sunflower,
hemp and rape (1.8-2.5) and high for potato
and sugarbeet (4.9-6.7). Energy use is low for
21.2.3 Results
Input requirements and impact
for the eight crops
The amount of any input required varies from
one crop to another (Table 21.1): from 0 (peas)
