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

PARALLEL SESSION 3C: SHEEP AND DAIRY PRODUCTION SYSTEMS 8 th Int. Conference on LCA in the
Agri-Food Sector, 1-4 Oct 2012
The general equation used to quantify land use impact is shown in Eq.1.
Q(t)).dt ( A.t = CF flow
LOI Inventory
occ occ E
Eq.1
where LOI corresponds to land occupation impacts, A is the used land surface area (m 2 ), tocc the occupation
time (the product of both term being the inventory flow) [m 2 .yr] and CFocc is the characterisation factor
for the occupation [m 2 ·yr·impact_indicator].
2.3. Characterisation factor data
Location is required to enable the link between the inventory flow and a spatial impact assessment using
regionalised impact factors, also known as characterisation factors (CFs).
Different impact pathways are considered, impacts on biodiversity and the impacts on a series of ecosystem
services. CFs from Pfister et al., (2010) are used for impacts on biodiversity. Such factors are based on
the ones provided in EI 99 (Goedkoop and Spriensma, 2001) and include ecosystem scarcity and vulnerability.
CFs for impacts on soil ecological functions, namely groundwater recharge potential, erosion resistance
potential, physico-chemical filtration and mechanical filtration potential are provided by Saad et al., (submitted).
An example of regionalised CFs for land use agricultural impacts on biodiversity adapted to the states
geographical context is illustrated in Figure 2. The CF for the remaining impact categories are given in the
main report (Jolliet et al., 2012).
Figure 2. Land use impact factor for biodiversity for the U.S. geographical context
3. Results
3.1 Inventory flow for feed production
Yield production measured in kg crop dry matter produced per unit surface (kg DM/m 2 ) is a main parameter
that enables converting a crop quantity needed to be grown into the necessary harvested area. Thus,
the smaller the yield, the larger the harvested area is required. As illustrated in Figure 3, yields for corn grain
vary considerably across the states from 0.4 to 1.1 kg DM/m 2 . In addition to Western U.S. states, where
Washington has the highest yield, states located in the Midwest, not only have high yields but also high productivity
(annual total bushels produced). These high-yield regions require a smaller harvested area than
states located in the South-eastern U.S., which have smaller yields. In general, between 1.5 and 2.5 m 2 of
land area are needed to be harvested to produce 1 kg DM of corn grain.
Combining state corn grain yields (on the y-axis) with national production fractions (on the x-axis), the
variable width graph presented in Figure 4 indicates the total land use area requirement needed in each state
to produce one kg of corn grain at the national level. Results per state, shown as the areas of the rectangles,
highlight states in the Corn Belt (Iowa, Illinois, Nebraska, Minnesota and Indiana) having high crop production
fractions and moderate yields. Conversely, states like South Dakota have slightly smaller yields (higher
land area) but smaller production, thus do not have sizeable contributions to corn grain land use area requirements
at the national level. Total land use impacts, reported as land use area requirements, for national
corn grain production sum up to 1.26 m 2 .yr/kg DM.
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