Agriculture Reference
In-Depth Information
agriculture area needed and the environmental impacts of food basket scenario 2 and 3 two
methods was used:
1.
The production (kg per ha) of the products from the four farm groups was combined so
they together cover the annual demand of the seven consumption categories in the
annual food baskets. The environmental impacts of the food basket were calculated
from the average impact of the four farm categories respective.
2.
The average production (kg per ha) of products from all the 12 ERA farms was
combined so they together cover the annual demand of the seven consumption
categories in the annual food baskets. The environmental impacts of the food basket
were calculated from the average impact of the all 12 studied ERA farms.
2.2.1 Nutrient surplus
The method for calculating nutrient balances follows those described in Granstedt (2000)
and Larsson and Granstedt (2010). The potential emissions of nitrogen were defined as the
difference between total input of nitrogen to the farm and the export from the farm in form
of agricultural products (meat, milk, grain and horticultural products) (Granstedt et al.,
2004). A steady state of the total nitrogen content is assumed. An increased content of Soil
Organic Matter (SOM) has however been observed in several studies of organic farms
(Granstedt and Kjellenberg, 2008; Hepperly et al., 2006; Mäder et al., 2002) which implies
that real losses of nitrogen can be lower than the observed surplus in the nutrient balances.
The potential nitrogen emissions from each farm group as a part of the total load from one
food basket was calculated using the equation:
A
i
N-surplus
= A
i
* A
i
N-surplus/ha
(2)
where A
i
N-surplus
is the N-surplus (kg) from the area used for one food basket from farm
group i, i=1-4, A
i
is the area for farm group i and A
i
N-surplus/ha
is the average N-surplus per
ha from the ERA farms included in farm group i.
The nitrogen surplus of one food basket was calculated using the equation:
A
A
A
(3)
N
surplus
i N
surplus
diff N
surplus
i14
where A
N-surplus
is the total N-surplus from the area used for food production per capita (i.e.
food basket), and A
diff N-surplus
is the summarised residual value of N-surplus for the seven
food product categories converted to area (ha). Both primary and official data were used in
the calculations. The same procedure was also used for global warming potential and
consumption of primary energy resources.
2.2.2 Global warning impact and energy use
The assessment of global warming impact and primary energy use followed the principles
of life cycle assessment (LCA) methodology (Lindfors et al., 1995), although a complete LCA
was not made due to the complexity of the systems studied. The LCA methodology is
primarily designed for assessment of single products, but the structure of the methodology
can also be used for larger systems. Here assessments where first made separately for the
agriculture, the processing and the transportation systems. There after these results where
used in assessment of the scenarios. Compared to a complete LCA the steps being omitted
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