"Meeting the Nitrogen Management Challenge: Arresting
the Nitrogen Cascade"
AAAS 2003 Symposium, February 15, 2003
(PowerPoint presentations attached)
Of the biogeochemical cycles, the nitrogen cycle has been altered the most
by human activity. Human fixing of reactive nitrogen now exceeds that of
all natural processes. Because of nitrogen's complex chemistry and the fact
that it is often the limiting nutrient in both terrestrial and aquatic ecosystems,
the effects altering the nitrogen cycle are often surprising and severe.
The majority of anthropogenic reactive nitrogen comes from the production
of ammonia for agricultural fertilizer that provides 40% of current global
food production. Additional nitrogen sources include livestock, fossil fuel
and biomass combustion, chemical production and waste management. From an
ecosystem perspective, the multiple chemical and biological transformations
of nitrogen produce a cascade of impacts that move among the atmosphere,
soils and water.
The nitrogen cascade will be utilized as the organizing principle for examining
human alterations of the nitrogen cycle, the consequences for ecosystems and
the economy. New strategies and opportunities for improved nitrogen management
will be the goal of the symposium. The timing of the AAAS meeting lies midway
between the second and third triennial, International Nitrogen Conferences,
and will allow an assessment of trends. In addition to summarizing what is
known about the biogeochemistry of the nitrogen cycle, critical issues such
as the excessive release of nitrogen in China, Europe and North America, and
its under availability in Africa, Latin America and other parts of Asia will
be addressed. Finally, an economic analysis of the nitrogen cycle and the implications
for management and policy intervention will be provided.
Contact webmaster at esa.org for the files below.
"Impacts of the Nitrogen Cascade on Ecosystems"
This presentation will set the context of the nitrogen cascade and the multiple
effects that each molecule of reactive nitrogen introduces into the ecosystem
and the economy. Specific examples of nitrogen damage will be documented.
The description will be quantitative in nature and will present a model that
will be utilized by the other speakers.
Dept. of Environmental Sciences, University of Virginia
"Fertilizer Use in Theory and
This presentation will demonstrate how nitrogen fertilizer is used and what
are the motivations for current practices that often involve excessive or
inappropriate use. It will also compare proposed alternative cultivation
practices and their implications for nitrogen management.
Agronomy Department, University of Nebraska
"Opportunities for Managing Fertilizer
There are multiple ways in which nitrogen is lost from agroecosystems. Reducing
these losses while maintaining the opportunity to increase system productivity
is the challenge that must be met for the efficiency of nitrogen use to be
improved. An understanding of the nitrogen cascade can provide insights as
to where intervention to reduce adverse impacts might be more effective.
Altering nitrogen use patterns also has implications for the fertilizer industry
that will need to be addressed.
Potash and Phosphate Institute
"Livestock and Reactive Nitrogen"
Animal agriculture contributes substantially to the quantity of reactive nitrogen
in the environment. For every unit of nitrogen contained in the protein of
animal products, 3 to 10 units of reactive nitrogen are lost to the environment.
Improving the efficiency of feed N utilization by animals can be achieved
by feeding protein closer to requirements and increasing production per animal
to enable a reduction in animal numbers for the same level of food production.
Animal diets can also be optimized to enable selection of crops that can
be produced with lower losses to the environment. Techniques are available
to reduce N losses from manure collection, storage, and application, but
unless these techniques are used in concert, the losses may only be transferred
from one location to another without having an overall impact. Opportunities
do exist to reduce N losses on individual farms, but it is a challenge to
develop and implement programs that will provide incentives to farmers.
Richard A. Kohn
Animal & Avian Sciences, University of Maryland College Park
"Effective Regulatory Strategies
for Controlling NOx Emissions from Power Plants"
Over the last two decades, there has been an increasing emphasis on reducing
emissions of NOx from existing industrial, combustion infrastructure in the
US, including electricity-generating plants. Power plants in the US emit more
than 5 million tons of NOx per year (about one fourth of US emissions). Other
major sources include large industrial boilers, cement plants, large diesel
engines and combustion turbines. The regulatory and technology history of NOx
control in the US has been characterized by weak requirements in the early
1970s and 1980s (from no control to about 30 percent reductions). This was
followed by rapid development, innovation, and application of advanced technology
capable of reducing emissions by over 90%. The "policy confusion" of
whether NOx control was counterproductive ("the so called " NOx disbenefit
issue") delayed the effective regulatory drivers till about 1994. The
more recent "multi pollutant "approaches of addressing all types
of emissions from combustion ( NOx, SO2, mercury, carbon dioxide, primary fine
particles including toxic trace metals) in an integrated manner will be described
including their cost and implementation benefits as well as policy hurdles.
Finally, this presentation will give results from a recently completed NESCAUM
report on the relationship between environmental regulation and technology
innovation in the area of combustion controls from power plants and automobiles.
The major finding of this report, that innovation in the US has consistently
occurred, not before, but after regulatory drivers with well defined targets
and deadlines were put into place, has serious implications for the future
direction of NOx controls.
Northeast States for Coordinated Air Use Management (NESCAUM)
"The Economics of the Nitrogen
There has been relatively little economic analysis of the nitrogen cycle and
the alteration to it. This analysis will identify some of the major economic
implications of different portions of the nitrogen cascade to suggest where
intervention might be most cost effective. A second analysis will utilize economic
comparisons to provide and economic set of criteria for choosing among mitigation
The Fletcher School of Law and Diplomacy, Tufts University