Agriculture Reference
In-Depth Information
The further defi nition of the two model systems was based on the as-
sumption that yields are determined by the level of fertilization and ir-
rigation. Therefore, M-Low is defi ned with a low input of fertilizers and
M-High with a higher fertilizer input. The NPK-budgets were calculated
based on farm gate inputs and outputs from an average farm with the same
crop production and management using a NPK-budget tool from the Or-
ganic Research Center [36,37]. Both systems were assumed to have 20%
green manure (red clover) in their crop rotation. Input of cattle manure,
rock phosphate and rock potash was then modeled such that M-High
reached a balance of 90 kgN/ha, 10 kgP/ha and 10 kgK/ha and M-Low a
balance of 0 kgP/ha and 0 kgK/ha (Table A2). For the M-Low N balance,
the lowest possible value was 54 kgN/ha due to atmospheric deposits and
N-fi xation.
Further, for M-Low irrigation was only included for the crops for
which irrigation is considered essential according to the Handbook [34],
whereas for M-High irrigation was also included for crops which “may
require irrigation”.
Based on the fi eld operations needed for each crop described in
Or-
ganic Farm Management Handbook
[35], the resource use in terms of fuel
and machinery was modeled according to resource use per unit process
[38] (see Supplementary Material for detailed description of the farming
model). The approach for determining yields and resource use was similar
to a previous study commissioned by Defra [39].
1.4.2 MODEL DISTRIBUTION SYSTEM
The model distribution system from farm gate to consumer's door was
modeled on a crop by crop basis based on published LCA reports for su-
permarket based food distribution chains [40,41,42] (Table 3). The chain
is thus assumed to consist of 200 km transport to and storage for 5 days
at regional distribution center (RDC), 50 km transport to and storage for
2 days at retailers and 6.4 km transport from the retailer to the customer's
home [40] (see Supplementary Material for detailed assumptions.) Trans-
portation from the farm to the RDC is assumed to be in a chilled 32 t truck
with an energy consumption of 22.9 mL diesel per euro pallet kilometer
