Redesigning Animal Agriculture

of diffuse nutrient loading on waters. Major
causes for concern arise from the following
production systems in the UK:
● Dairy and beef cattle production in
lowland Wales and western England;
● Sheep production in sensitive upland
areas of Wales and northern England;
● Pig production on intensive outdoor
pig-lots in lowland permeable areas;
● Cattle and sheep production through
strip grazing in lowland permeable
catchments;
● The disposal of poultry litter from intensive
rearing units in eastern England.
The impact of these trends on nutrient
export to waters is spatially variable across
England and Wales. This is illustrated in
Fig. 11.6, where the spatial variations in the
rates of N and P export per hectare of agricultural
land are shown for 1931 and 1991
(after Johnes et al., 2007). The highest rates
of both N and P export from agriculture are
occurring in the lowland intensive dairying
regions, resulting from the intensity of livestock
production in these areas. The lowest
rates of N and P export occur in the upland
regions and also in flatter arable lands of East
Anglia. The low rates of export in the upland
regions result from relatively low intensity
agricultural production in the national context.
The low rates of export in East Anglia
result from the low intrinsic vulnerability
of this flat and dry landscape to water-borne
nutrient transport, again in the UK context,
despite the intensive agricultural production
practised in this region, both in the present
day and also in the baseline year.
These trends are interesting from the
perspective of illustrating national patterns
of nutrient flux from agriculture. However,
this does not mean that the waters in the
uplands and East Anglia are of better quality
or ecological status than waters in the remainder
of England and Wales. What is of greater
ecological significance is not the absolute
rate of nutrient flux and the resulting N and
P concentrations instream, but the degree of
deviation (pollution) that is potentially experienced
by the biota living in the water body.
Although water bodies in upland regions have
Ecological Restoration Targets 197
typically low nutrient concentrations they are
nevertheless under considerable pressure
from diffuse agricultural sources, with the
greatest rates of increase in nutrient loading
in the UK predicted for the uplands of Wales,
Cumbria and south-west England. The rivers
in eastern England, by contrast, whilst having
typically moderate to high nutrient concentrations,
have experienced, in many instances, a
decrease or only a modest increase in nutrient
loading over the period 1931–1991, with
marked spatial heterogeneity evident in the
trends within each region. In order to comply
with the definition of ‘Good Ecological
Status’ under the Water Framework Directive,
it is necessary to develop management strategies
which will generate nutrient concentrations
capable of sustaining a healthy ecology
in terms of both structure and function in
these impacted waters, regardless of absolute
nutrient concentration per se. The challenge
is to determine which management strategies
are most appropriate in each region, given
the different starting points and pressures for
each water body, and to assess whether broad
regional strategies can deliver an appropriate
degree of nutrient export control for individual
water bodies within each region.
Identifying the Nature and Scale of
Appropriate Management of Diffuse
Pollution Under the WFD
There are a wide range of options available
for reduction of nutrient export from agricultural
sources, including modifications
to the rates and timing of fertilizer applications
to crops and grass, genetic modifications
to crop varieties to improve nutrient
uptake efficiency, and for animal agriculture
a wider range including:
● Manipulation of digestive physiology
through animal selection and
genomics;
● Modification of the nutrient content
and availability in animal feeds;
● Modification of the timing, method and
rate of manure application to crops and
grass;