Redesigning Animal Agriculture

Quarterly flow weighted mean
nitrate concentration (NO3−N mg l−1 )
12
10
8
6
4
2
1930
UK Agriculture
Act, 1947
Second World
War
1940
illustrated using three long-term data sets
for water bodies in England and Wales in
Figs 11.3 and 11.4. In Fig. 11.3, long-term
trends in nitrate concentrations in the
River Thames at Walton on Thames are
summarized (after Onstad and Blake, 1980;
supplemented with more recent monthly
data from the Environment Agency routine
water quality monitoring programme). Key
change points in the nitrate concentration
trend occurred in conjunction with major
phases of change in the social, economic
and political systems. The first change
point occurred during the Second World
War, when much of the traditional grazing
land was ploughed up, and many marginal
lands were drained and cultivated
in response food shortages and the UK
Government ‘Dig for Victory’ campaign. In
the post-war period, the 1947 Agriculture
Act was enacted to support Government
policy to develop self-sufficiency in food
production at a time of severe food rationing
following the collapse of food production
and support in the post-war era.
A third change point is apparent when
the UK joined the EU in the early 1970s
and benefited from the economic support
structures introduced under the Common
Agricultural Policy (CAP).
Ecological Restoration Targets 191
EU Common
Agricultural Policy
1950 1960 1970 1980 1990
Data source: Onstad and Blake, 1980;
Environment Agency Data Archive.
Fig. 11.3. Long-term trends in nitrate enrichment in the River Thames, 1930–2000.
2000
In Fig. 11.4, two long-term data sets
collected by the Freshwater Biological
Association at Windermere (now the Centre
for Ecology and Hydrology, Lancaster) are
presented, along with the output from two
models reconstructing the likely P enrichment
history for Windermere and Esthwaite
Water in the English Lake District (after
Bennion et al., 2005). In these it is apparent
that TP concentrations have more than
doubled in both lakes since the mid-19th
century, evident in both the observed P
chemistry data, model simulations of nutrient
export from catchment to lake, and in the
response of the diatom communities in each
lake. Key change points in both lakes can be
tied to the opening of STWs on the shores of
each lake, and the subsequent introduction
of P stripping at these works in the late 20th
century, but underlying these change points
is a general trend of enrichment which is
tied to increased diffuse P export from agricultural
practices in the catchment of each
lake (Bennion et al., 2005).
The nature and extent of diffuse nutrient
enrichment of waters is clearly a problem
for the competent authorities charged
with the implementation of the WFD in each
member state, and will be a particular problem
in those member states with intensive