Agriculture Reference
In-Depth Information
1.5.2.2 BENCHMARKING BASED ON LCA
The distribution phase has an important contribution to the environmental
impacts of the model systems and in particular for the impact categories
non-renewable resource use, Global Warming Potential (GWP) and hu-
man toxicity (Figure 2). The use of non-renewable resources in the case
system is similar to M-Low, while the impact of M-High is around 30%
lower (Figure 2). The GWP of the case is about 40% higher than both
model systems. The difference in GWP between M-Low and the case was
related to differences in management processes. The on-farm production
of seedlings and composting of woodchips, respectively, may not be as
efficient as centralized production of seedlings and use of only green ma-
nure and rock phosphate for nutrient supply. The impact category Phos-
phorus use was calculated to be higher in the case-study as compared to
the model systems due to the use of vermiculite, but it is necessary to bear
in mind that the levels of phosphorus use were relatively low for all three
analyzed systems. The case system and M-Low have significantly lower
aquatic eutrophication N potential, terrestrial ecotoxicity and aquatic eco-
toxicity than M-High. This is because these impact categories are more
dependent on the applied fertilization and irrigation levels rather than on
capital goods and on-farm diesel and electricity. Aquatic ecotoxicity and
human toxicity effects of the case were also lower than both model sys-
tems. Aquatic ecotoxicity levels were found to be similar for model sys-
tems while human toxicity of M-Low was shown to be slightly higher than
M-High.
In addition, for model systems, environmental impacts for all impact
categories are clearly dominated by agricultural cultivation (Figure 2). As
for the case-study farm, more than 50% of the non-renewable resource
use in the model systems is from use of crude oil (Figure 4). Nearly 20%
of non-renewable resource use in model systems comes from natural gas,
while for the case it is only 10%. Uranium ore has a relatively high contri-
bution, nearly 20% of the result for all systems, as the electricity mix in the
UK includes nuclear energy. Hard coal contributes to around 9% of the re-
source use and the remaining raw materials play a minor role (5% or less).
