18 D. Norse, J.B. Tschirley Agriculture, Ecosystems and Environment 82 2000 15–26
equilibrium with rainfall Nicholson and Tucker, 1998, and overgrazing was not the major factor
in causing observed changes in the desert margins Behnke et al., 1993. Research revealed that suc-
cessful rangeland management depended as much on cultural and institutional factors as ecological
and technical ones. More than one billion dollars of development aid appears to have been directed
to symptoms rather than causes of change because of misunderstandings about the bio-physical and
socio-economic determinants of dryland producti- vity and degradation FAO, 1986.
3. Components of policy analysis and implementation
The role of science in policy can be set out as a sequence of contributions that includes the following:
• problem identification;
• strategy formulation;
• selection of policy options;
• policy implementation;
• setting of regulatory standards;
• monitoring and evaluation.
This scientific foundation and sequence of research contributions can be illustrated using the global nitro-
gen N cycle as an example. 3.1. Problem identification
Human activity is disrupting the biogeochemical ni- trogen cycle at various spatial scales and through a
variety of mechanisms. Food and agricultural produc- tion has played a role in this disruption Smil, 1985;
Socolow, 1998 and will continue to do so for the fore- seeable future as population and income growth bring
about greater inputs and outputs of nitrogen per unit of production Table 1.
The main problems fall into two groups. First, those that are already global in scale and are part of
the main focus of the IGBP, e.g., the increase in atmo- spheric concentrations of nitrous oxide N
2
O which contributes to global warming and higher ultra-violet
UV radiation at the earth’s surface IPPC, 1995; Mosier and Kroeze, 1998. Second, those problems
that are global in scope and in the future may be global in scale in that they are found in discrete loca-
Table 1 Global emissions of N
2
O from agricultural soils
a
Mt N per year 1996
2030 Direct soil emissions
Mineral fertilisers 0.87 0.18–1.6
1.2 Animal wastes
0.63 0.12–1.1 1.0
Biological N
2
fixation 0.12 0.02–0.2
0.25 Crop residues
0.37 0.07–0.7 0.58
Cultivated histosols 0.1 0.02–0.2
0.1? Subtotal
2.1 0.4–3.8 3.13
Animal production including grazing animals Animal waste management systems
2.1 0.6–3.1 3.2
Indirect emissions Atmospheric deposition
0.36 0.07–0.7 0.58
Nitrogen leaching and runoff 1.4 0.11–6.7
1.9 Human sewage
0.22 0.04–2.6 0.33
Subtotal 1.98 0.22–10.0
5.61 Total
6.2 1.2–16.9 9.14
a
Source: Mosier and Kroeze 1998 and FAO 2000.
tions of the major continents, but have no well-defined feedbacks on the earth system. They include the re-
lease of ammonia from intensive livestock systems and build-up of nitrate fertiliser residues in ground
and surface water. The latter problem first emerged in the developed countries in the 1970s as a conse-
quence of agricultural intensification, but are now appearing in the developing countries Sinha, 1997;
Zhang et al., 1996.
Such problems are difficult to address through po- licy changes because of gaps in our scientific under-
standing of the processes and of the complex spatial and temporal relationships between the impacts and
the driving forces. The impacts of ammonia from live- stock, e.g., can be local and regional and include leaf
damage to trees as well as loss or shifts in biodiver- sity through the eutrophication or acidification of peat
bogs, freshwater ecosystems and woodlands Pitcairn et al., 1998. The impacts of nitrates in drinking water
include human health risks, though the extent and severity of these risks is disputed Addiscott et al.,
1991. Eutrophication of rivers, lakes and estuaries can lead to reduced fish production, but up to a certain level
the nutrient inputs boost fish production, and there can be wide differences between different water systems
as to the source of the nutrients and how they will
D. Norse, J.B. Tschirley Agriculture, Ecosystems and Environment 82 2000 15–26 19
respond. Consequently policy difficulties have arisen because of disagreements amongst scientists as to the
contribution of mineral and organic fertilisers to the eutrophication and the best way to control it.
Scientific research comes into problem identifica- tion and quantification of N cycle disruption at many
points. There is, e.g., uncertainty about the size of the main sources and sinks of N
2
O with 10–20-fold differences between the highest and lowest estimates
for the contribution of agricultural soils to the global N
2
O budget IPCC, 1997. There is no doubt, how- ever, that atmospheric concentrations of N
2
O are in- creasing annually by about 0.3. And there is a wide
body of research which shows that: a much of this increase comes from mineral N fertilisers and animal
wastes from agriculture Mosier and Kroeze, 1998, and b continuing intensification will maintain these
increases with a possible doubling of agriculture’s contribution by 2050 Smith, 1999, though there are
sound arguments for believing that the increase might be lower at around 50 FAO, 2000.
More systematic observations are therefore required at all scales as well as research into the processes
involved in the N cycle, such as denitrification rates in the main managed and unmanaged terrestrial and
freshwater ecosystems. An integration and scaling mechanism is also needed to take these ecosystem
measurements and model them at the global level. This is both a technical challenge requiring improve-
ments in N cycle modelling and an institutional task, notably through the bringing together of in situ and
satellite observations.
3.2. Strategy formulation It follows from the above that science may con-
tribute to mitigation strategies by establishing the primary anthropogenic sources of N disrupting the
global N cycle, and how these may change over time. It can quantify the time trends for this disruption
by setting parameters and constructing mathematical models. The latter show that continued agricultural
intensification, which is essential to meet future food demands, will, e.g., increase emissions of N
2
O which has a stronger radiative forcing potential than carbon
dioxide IPPC, 1995. Science can determine the scientific pros and
cons of strategies to mitigate N cycle disruption and thereby help policymakers set priorities for action.
Thus, a central objective should be to steer agriculture on to a more sustainable growth path, and the main
mechanisms will be the development of “greener” technologies through R D and the promotion of
their adoption through regulatory measures, voluntary codes and economic policy instruments.
3.3. Selection of policy options This element of policy formulation typically goes
beyond the normal boundaries of the IGBP. In the 1970s when the build-up of groundwater nitrate first
became an issue in Europe, a common response was to expand scientific investigations of the movement
of nitrates through the soil and aquifer. Nitrate moni- toring, lysimeter studies, watershed modelling were
used to determine which production systems are the primary cause of the build-up, how widespread the
problem was and how soon policy action might be re- quired. Research has demonstrated that organic inputs
to high input systems can be just as harmful as badly managed mineral fertiliser-based systems Addiscott
et al., 1991.
Research has also led to the identification of para- meters for assessing potential impacts from both ma-
nure and fertiliser and strategies for managing them. This is a good first step toward assisting policymakers
but scenario development, management and policy op- tions, and economic analysis are also required, high-
lighting the need for social science as well as natural science inputs to the policy process. Economic factors
became an important issue because of the high cost of treatment to bring nitrate contaminated water to an ac-
ceptable drinking water quality. Price factors continue to play an important role in policy selection with grad-
ual acceptance of the need for using both technological and economic instruments such as charges or levies.
3.4. Policy implementation The above discussion noted that the earliest scien-
tific inputs to agricultural nitrate policy development tended to be of a bio-physical nature but as the range
of policy instruments was widened more support from economic research was required. The breadth of the
scientific contribution to policy implementation can be illustrated by three examples: the setting of regulatory
20 D. Norse, J.B. Tschirley Agriculture, Ecosystems and Environment 82 2000 15–26
standards; the development of response models to test the feasibility and possible impact of pollution taxes
or environmental service payments; and the formula- tion of codes of conduct.
In the design and implementation of policy instru- ments it is important to know how quickly an aquifer
or catchment system will respond to reductions in ni- trogen use and at what tax level farmers would start to
lower nitrogen application rates. Modelling has played a vital role in both these cases. In the former by mak-
ing it possible to extrapolate in space and time from a small number of observations to estimate how soon
different policy measures will start to improve water quality. In the latter by helping to determine the pos-
sible impact of pollution taxes on fertiliser use, farm profitability and viability and compare their efficacy
with alternative policy instruments.
These examples also illustrate how bio-physical models can complement economic models. For ex-
ample, by showing how pollution taxes could be undermined if farmers applied mineral fertilisers in
the wrong season or switched to poorly managed manure. Such models have been constructed in many
developed countries and can be readily parameterised for use in developing countries as they start to face
similar problems and policy needs.
Regulations and economic instruments alone are seldom sufficient in achieving policy objectives. There
are, e.g., limits to the monitoring of farmer’s com- pliance with regulatory standards. Hence European
policymakers are emphasising codes of conduct for good farming practice Dwyer and Baldock, 1999
based on research to determine the management prac- tices that minimise leaching and runoff from crops
and grassland MAFF, 1999.
3.5. Setting regulatory standards Scientific research has been able to provide much of
the quantitative framework required to set meaningful standards to reduce N cycle and ecosystem disruption
to tolerable levels although the transition time may be long. Given knowledge of soil type, rainfall, average
nitrate leaching rates, volatilisation rates, etc., it is possible to prepare critical load estimates, identify
the main areas at risk and designate nitrate vulnerable zones in response to policy directives EU, 1991. Sci-
entifically based regulations can then be set for maxi- mum application rates of mineral fertiliser restrictions
on the timing of manure spreading and reductions in permitted livestock density rates as in the Netherlands.
3.6. Monitoring and evaluation The scientific inputs to monitor determine which
variables to measure, how to measure them and with what frequency, to parameterise the models, and to
assess the effectiveness of different technical or nutri- ent management measures. There are possibilities to
align the GCTE more closely with the policy process through projects that: a help refine monitoring and
evaluation techniques, b provide a wider terrestrial ecosystem framework within which to assess sectoral
contributions to N cycle disruption, and c contribute to the scaling up of national or regional N cycle dis-
ruptions to the global level.
These two possibilities relate closely to concerns raised by FAO and other international bodies regard-
ing the lack of integrated monitoring data on the condition of terrestrial ecosystems, with well-known
researchers, e.g., concluding that soil erosion is greatly undermining food security and others argu-
ing that it is not. They consider that this lack of monitoring data is a major constraint to policy for-
mulation in their respective areas of responsibility, to the assessment of issues such as land degradation,
to global change research and to the functioning of the international conventions on climate change, bio-
diversity and desertification. The latter is considered particularly important because member countries of
the United Nations had agreed to establish these in- ternational conventions without considering whether
mechanisms existed for providing the scientific in- formation needed to set priorities and evaluate or
monitor policy performance. Their response was to establish a Global Terrestrial Observing System
GTOS ICSUUNEPFAOUNESCOWMO, 1996, 1998, which is helping to establish GT-Net, a global
system of terrestrial observation networks to fill this monitoring gap Fig. 2.
These contributions of science to policy develop- ment and implementation have been presented as a
closed logical sequence. In reality, however, it is an iterative, cyclical process with monitoring and evalua-
tion of policy implementation feeding back into further policy planning and refinement. The pressure, state,
D. Norse, J.B. Tschirley Agriculture, Ecosystems and Environment 82 2000 15–26 21
Fig. 2. GT-Net — a global system of terrestrial observation networks.
response framework is an example of a tool that was developed by the Organisation for Economic
Co-operation and Development OECD in the 1970’s for use in considering policy options related to air
pollution. Its application to other environmental prob- lems has been considerably broadened in recent years.
However, understanding the linkages between driving forces, states and responses, complex as they may be,
is only part of the picture. Sustainability components the economic, social and environmental dimensions
and how they interact must also be assessed through the use of analytical tools such as modelling and
integrated assessment techniques. Fig. 3 provides an example of a framework for sustainability analysis.
Such frameworks underline the importance that an issue like agriculture’s contribution to the disruption
of the N cycle must not be tackled in isolation from other components of the N cycle or from other actions
to promote sustainable agriculture. Thus the scientific support to policies to reduce agriculture’s impact on
the N cycle must be part of a broader bio-physical and social science agenda for integrated farming,
organic food marketing, and other agri-environment measures that are part of the multifunctional character
of agriculture FAO, 1999.
4. Principles for policy relevant science
