LCA Food 2012 in Saint Malo, France! - Manifestations et colloques ...

PARALLEL SESSION 5B: METHODOLOGICAL CHALLENGES FOR CROP PRODUCTION SYSTEMS 8 th Int. Conference on
LCA in the
Agri-Food Sector, 1-4 Oct 2012
kg CO 2 eq ; or g PO 4 3- eq; or MJ eq
2.5
1.5
0.5
-0.5
-1.5
-2.5
Climate Change
(kg CO 2 eq)
W100 N P50W50 N0 P50W50 N W100 N P50W50 N0 P50W50 N W100 N P50W50 N0 P50W50 N
Figure 1. Potential impacts per kg of wheat grains (bread making quality) from sole cropping, and according
to different propositions for allocation of impacts among grains of wheat and pea in intercrop yield. W100:
wheat sole crop. P50W50: substitutive intercrops of pea and wheat (“50” indicates half of the recommended
plant density when sole cropped). Crops are N-fertilised (“N”: 190 kg N ha -1 on sole cropped wheat, and
45 kg N ha -1 at the beginning of stem elongation on N-fertilised intercrops), or not (“N0”). MASS: mass
allocation. ECO: economic allocation. NITRO: allocation according to the quantity of Nitrogen in wheat and
pea grains. SYST: avoided allocation by system expansion. Values are means (n=3) ±SE (Standard Errors).
3.3. Estimated impacts related to ICs grain production
Eutrophication
(g PO 4 3- eq)
Two comparisons were made: i) equivalence of area: impacts of IC cropped on 1 ha, compared to 1 ha of
a combination of SCs according to relative sown densities in IC; ii) equivalence of production: impacts of IC
cropped on 1 ha, compared to a combination of SCs producing the same quantity of wheat and pea grains as
in IC (fig. 2). These comparisons took into account grain yield and LER (table 1) to perform comparison on
the basis of equivalence of cropped area, and equivalence of production, respectively.
Comparison on the basis of equivalence of cropped area showed that, relative to sole crops, impacts of
un-fertilised intercrops were reduced by 52%, 41%, and 36%, for CC, EU, and CED, respectively. Comparison
on the basis of equivalence of production shown that, relative to sole crops, impacts of un-fertilised
intercrops were reduced by 54%, 49%, and 46%, for CC, EU, and CED, respectively. N-fertilisation increased
impacts relative to un-fertilised intercrops, but impacts were less than those of sole crops, whatever the way
of comparison (Fig. 2).
MASS
ECO
NITRO
SYST
No allocation (sole crop)
Total Cumulative Energy Demand
(MJ eq)
469