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Application
Representative farm systems were used for application of the Cost-Cube framework.
For each farm system, the total livestock numbers, crop areas and manure production
were defined (Table 1). These farm type definitions were based on those used in a
previous project (Chambers, 2002). The vector model was then used to calculate total
pollutant losses for different combinations of climate, soil drainage and soil texture
acting upon each farm system. These combinations were chosen to represent the
range of environment conditions in England and Wales, including sandy loam and
clay loam soils, and low (650 mm) and high (1100 mm) annual rainfall locations.
For each farm system, a list of applicable pollutant control measures was drawn from
a review of potential mitigation measures, and the annual cost of implementation
calculated in proportion to land area, livestock numbers and quantity of managed
manure. Whole farm costs for the dairy system were calculated as being as low
as £500 per year for measures that reduced pollutant losses by activities that can
be equated with good agricultural practice. For example, the avoidance of slurry
spreading on hydrologically well-connected field margins, or avoiding grazing
high-risk fields on wet days. However, the field evidence for the efficiency of these
measures in reducing pollutant mobilisation and delivery is variable and confidence
in their effect is low. In contrast, there are other measures which if implemented
are known to be guaranteed to reduce potential pollutant inputs but which are also
very costly. For example, the reduction of dietary nitrogen intake or the removal of
mineral fertiliser from the system costs £10,000 and £50,000 per year, respectively.
For the arable system, the costs of mobilisation and delivery control measures were
generally calculated to be higher due to the greater land area, and the greatest
costs were associated with either the removal or change in type of mineral fertiliser
applications.
Table 1:
Summary of the attributes allocated to each Representative Farm
System in the modelling process
Farm System
Dairy (grass)
Animal
count
270
Excreta
(t/year)
5,040
Managed
manure (%)
60
Field area
(ha)
150
Fertiliser
(kg N/ha)
190
Breeding pigs (indoor)
1,330
2,125
100
70.5
145
Broilers
150,000
2,500
100
436.7
145
Arable
-
-
-
300
165
For the broiler system, with the exception of feed antibiotics, the greatest costs were
taken to be associated with the changes in management of the large arable land
area required for the spreading of the litter. However, it was also considered that
there was the potential to save £42,700 per year by the proper accounting of the
nutrient value of the litter and reducing the mineral fertiliser applications. Such a
saving could potentially off-set some of the lesser measure costs, such as improved
manure application timing, and thereby produce a net environmental and economic
benefit. A similar situation was taken to exist for the indoor breeding pig system. Due
to manure being managed as slurry rather than solids, it was considered that there
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