Agriculture Reference
In-Depth Information
The main result of the emergy evaluation for the case system is the
transformity of the vegetables, which amounts to 5.20 × 10
6
seJ/J with
L&S and 5.54 × 10
5
seJ/J without (Table 5). The Emergy Yield Ratio
(EYR) of 1.15 disregarding L&S shows that free local environmental ser-
vices (R) contribute with only 0.15 seJ per seJ invested from the society.
The renewability indicator shows that the system uses 13% local resources
when disregarding L&S but only 1% when including L&S. The latter re-
fl ects that L&S is considered as non-renewable.
Disregarding L&S, the emergy profi les of the case system are as fol-
lows (calculated from Table 4). Purchased miscellaneous materials for
the cultivation phase contribute 38% of total emergy used. Fuel used for
cultivation and electricity used for production of seedlings are the big-
gest fl ows with 18% and 11%, respectively. Notably, irrigation contributes
24% of the total fl ow with the water used constituting the most important
element (17%). Likewise, the woodchips, used as soil enhancement and
used to produce potting compost, contribute with 10% and farm assets
contribute with 7%. The diesel used on the weekly round-trip was esti-
mated to 465 L/year (1.6 × 10
10
J, Table 4) and it is the major component
of the emergy used in the distribution phase (7% of the total emergy used).
Analyzing the case system using the LCA perspective, the processes
related to the cultivation phase have a much larger environmental impact
than the processes involved in the distribution phase, for all nine catego-
ries (Figure 2). The LCA impact category non-renewable resource use in-
cludes all direct and indirect use of fossil and nuclear fuels converted to
MJ. Crude oil in the ground contributes more than 50% of the total raw
materials for energy (Figure 3). Crude oil is used to produce diesel for
operating tractors and pumping the water for irrigation, and to a smaller
extent for the manufacture and transport of other inputs.
1.5.2 BENCHMARKING AGAINST MODEL SYSTEMS
An important difference between the food supply system of the case study
and the model systems is the amount of food lost. The long chain in the
model systems generates a high percentage of food loss, up to 29% for root
vegetables [42]. The direct marketing of the case system implies that the
