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3
NATURAL RESOURCES AND AGRICULTURAL PRODUCTIVITY
Chapters 1 and 2 looked at metrics related to the demand side of food security―poverty
and food consumption and outcome measures. This chapter changes course and looks at supply-
side aspects of sustainable food security, summarizing presentations and discussions about
measuring agricultural productivity and natural assets, examining composite indicators for
sustainable production and natural resource use, and the effect on the environment of achieving
food security.
MEASURING AGRICULTURAL PRODUCTIVITY AND NATURAL ASSETS
This first section examines a variety of metrics associated with changes in agricultural
productivity and natural assets. Richard Perrin describes two standard productivity measures—
single and multiple factor productivity and then links these to projects of future food demand to
illustrate the extent to which productivity must expand in the coming decades. A second
presentation links spatially explicit measures of agricultural productivity and eco-system
services. Steve Polasky then describes approaches to measure changes in the value of eco-system
services resulting from land use changes. The final presentation talks about various metrics
associated with the supply and use of water resources for agriculture.
APPROACHES FOR MEASURING PRODUCTIVITY AND NATURAL ASSETS
PRODUCTIVITY METRICS VERSUS FOOD SECURITY1, 2
Richard K. Perrin, University of Nebraska–Lincoln
Productivity
Richard Perrin explained that the basic definition of productivity is output divided by
input. He noted that the growth of productivity is more important than any particular level itself.
Single-factor productivity, such as tons of wheat per hectare, is conceptually straightforward. A
more comprehensive measure is multiple-factor productivity (MFP), defined as an index of
1
Prepared jointly with Lilyan E. Fulginiti, University of Nebraska–Lincoln.
2
The presentation is available at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_060826,
presentation by Richard Perrin (February 16, 2011).
33
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34 A SUSTAINABILITY CHALLENGE: FOOD SECURITY FOR ALL
outputs over an index of inputs. MFP is complex and subject to many different measurement
approaches. The productivity numerator includes only measurable outputs that contribute to
human welfare, and the denominator considers only measureable inputs that we think are
important.
Productivity growth can help gauge progress toward future food security, given the
limited potential for increasing resources. For the food producing sector, Perrin noted, these
basic resources include land, water, and natural resources and critical factors such as climate and
ecological resilience. The supply of other inputs, including labor and chemicals, seems to be in
sufficiently elastic that they would not hinder food security in the future. It is the basic resource
productivity that will matter.
Growth in Food Demand versus Growth in Productivity
Comparing projected growth in food demand with growth of productivity is one useful
way to frame the issue of food security. A commonly accepted estimate of the increase in food
demand by 2050, developed by the United Nations Food and Agriculture Organization (FAO), is
70 percent (Table I 3-1).
TABLE I 3-1 World Food Demand Growth, 2010-2050
Source of Growth Total Increase (%) Annual Rate of Increase (%)
Population growth 32 0.7
Income growth 38 0.8
Total increase 70 1.34
SOURCE: Presentation by Richard Perrin, University of Nebraska–Lincoln, February 16, 2011.
Conceptually, a productivity growth rate of 1.34 percent is not a necessary condition for
achieving the 70 percent goal. But this growth rate implies that 70 percent more could be
produced by 2050 with the current resources devoted to agriculture. If the growth rate were
lower, additional resources would be required if demand growth were to be met.
Trends in Measured MFP versus a Goal of 1.34 Percent
World agricultural productivity growth rates, both single factor productivity (grain
yields) and multifactor productivity have been relatively stable for the past 15 years, at a rate
very near the 1.34 percent goal. Though the MFP growth rate has increased since the 1960s, the
rate of growth for grain yields has declined since the 1960-1980 period, as shown in Figure I 3-1.
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NATURAL RESOURCES AND AGRICULTURAL PRODUCTIVITY 35
FIGURE I 3-1 Crop yields versus MFP—world.
SOURCES: Authors’ calculations from USDA FAS data, Fuglie (2008).
If the 1.34 percent growth target for productivity alone is not met, additional resources
will be required. Such resources can be attracted into agriculture only if food prices rise,
jeopardizing food security for some. Growth trends for cropland and irrigation do not encourage
optimism for new resources.
Conclusions
Perrin stated that world agricultural productivity growth rates are perhaps declining
slightly, but in recent years they appear to have been sufficient to provide security in 2050 if they
were to persist. He also noted that it is not certain that these rates will persist, and unfortunately,
the available measures of MFP are not measures of the productivity of those resources that are
most likely to be limiting—land, water and natural resources.
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36 A SUSTAINABILITY CHALLENGE: FOOD SECURITY FOR ALL
EXPANDING AGRICULTURAL PRODUCTIVITY MEASURES AND LINKING TO
ECOSYSTEM SERVICES—A SPATIALLY EXPLICIT APPROACH3
Stanley Wood, International Food Policy Research Institute
Stanley Wood described a new project, HarvestChoice,4 which is developing a set of
spatially explicit measures of agricultural productivity and ecosystem services, as well as
indicators of poverty and hunger. The goal of the project is to examine the links between hunger,
poverty, and agricultural productivity measures and ultimately to improve long-term agricultural
productivity, increasing human welfare. The project focuses on Sub-Saharan Africa and South
Asia, where productivity increases have stagnated over the past decades.
Wood described some of the key variables included in the project, beginning with the
agricultural base: slope, aspect, drainage, and elevation; location of settlements, ports, and
markets; and basic infrastructure, such as roads and information and communications
technology. This layer is then overlaid with data on the incidence of pests and diseases as
constraints to agricultural productivity and the incidence and severity of droughts and surface
runoff. This collection of data provides a way of understanding and characterizing the production
environment, which can then be combined with data illustrating the biophysical suitability of
different types of crops.
The project also includes detailed information on the location and extent of human
welfare metrics, which can be analyzed together with the agricultural productivity information
described above. Wood showed a map of Africa illustrating the extent to which rising rural
population density is increasing stress on critical natural resources (Figure I 3-2).
In summary, he noted that spatially explicit variables have a key role to play in
understanding the where and why of hunger, poverty, and productivity measures. They provide a
way to understand the interplay of human welfare, agricultural production, and ecosystem
services as well as to evaluate specific interventions.
Wood acknowledged that there are a number of spatial data issues. For example, maps
give the illusion of precision and accuracy, and the reliability of remotely sensed data is not
always strong. However, the data may be good enough—fit for the purpose of strengthening the
evidence base to make key decisions.
3
The presentation is available at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_060826,
presentation by Stanley Wood (February 16, 2011).
4
Funded by the Bill and Melinda Gates Foundation and conducted by the Institute for Food Policy Research (IFPRI)
and the Center for International Science and Technology Practice and Policy at the University of Minnesota.
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NATURAL RESOURCES AND AGRICULTURAL PRODUCTIVITY 37
Population Density (#/km2)
Which Rural Population Density? 0 - 20
21 - 40
41 - 60
61 - 80
81 - 100
Rising population densities are increasing the 101 - 150
stress on resources important to the poor 151 - 300
301 - 500
> 500
Rural population (#) on Rural population (#) on
Rural population (#) on
crop land area (km2)
total land area (km2) quality-adjusted
crop land area (km2)
FIGURE I 3-2 Which rural population density?
NOTE: White-masked areas include inland water bodies, protected areas, urban areas, irrigated areas,
closed forest, and land not suited for pasture or rainfed crops.
SOURCE: HarvestChoice, 2010.
MEASURING PRODUCTIVITY AND NATURAL ASSETS: MEASURING AND
VALUING NATURAL ASSETS5
Stephen Polasky, University of Minnesota
Steve Polasky explained that ecosystems, including agricultural systems, provide a wide
variety of goods and services to people. Examples include food, water quantity and quality,
carbon sequestration, recreation, and aesthetics. Land use and land management decisions result
in both intentional and unintentional affects on the bundle of services provided. However, these
effects are generally not factored into decision making, because monetary values are not assigned
to most ecosystem services. This can result in the loss of services valuable to the environment
and human society. He stressed the importance to sustainability of being able to make good
decisions about future land use and the need to look at trade-offs. He noted that relying on the
market system is not sufficient; it is necessary to pay attention to ecosystem services that are not
valued in the market place. Furthermore, the ecological data necessary to value ecosystem
services are very limited.
5
The presentation is available at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_060826,
presentation by Steve Polasky (February 16, 2011).
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38 A SUSTAINABILITY CHALLENGE: FOOD SECURITY FOR ALL
Polasky described activities undertaken through the Natural Capital Project’s InVEST6 to
develop a set of tools integrating the value of ecosystems services and highlighting potential
trade-offs. The tool is based on a set of computer-based models, including biodiversity and other
ecosystem services. It is spatially explicit and driven by future scenarios. It is also flexible and
transferable. Polasky noted that the tool is data intensive and that ecological data are limited. He
remarked that eco-data collection is much less advanced than the poverty and nutrition data cited
in the earlier workshop sessions.
The InVEST tool has been used in Minnesota to compare impacts on ecosystem services
and biodiversity from actual changes in land use between 1992 and 2001 with alternative
scenarios. For example what would have been the likely impacts if there was no agricultural
expansion or urban expansion etc. The analysis focused on the following: ecosystem services—
water quality and carbon sequestration; biodiversity—grassland bird habitat, forest bird habitat,
and general biodiversity; and return to landowners from agricultural production, timber
production, and urban development. He presented a series of slides illustrating how alternative
land-use scenarios affect each of these key variables and the need to have a complete set of
metrics (e.g., Figure I 3-3).
Baseline No Ag No Urban New Ag New Forest Conservation
$4,000
Agriculture
$3,000
$2,000
$1,000
$0
-$1,000
2001 price
$4,000
Forestry and cost in
$3,000
2001
$2,000
$1,000 1992 price
and costs in
$0
2001
-$1,000
$4,000
Urban
$3,000
$2,000
$1,000
$0
-$1,000
Baseline No Ag No Urban New Ag New Forest Conservation
Million 1992 US $
FIGURE I 3-3 Change from 1992 to 2001 by scenario: Market returns to agriculture, forestry, urban
areas.
SOURCE: Presentation by Steve Polasky, University of Minnesota, February 16, 2011.
In summarizing the presentation, he noted that incorporating the value of ecosystem
services in land use decisions can result in a higher level of services being provided as well as a
higher value of total goods and services. He also noted that agricultural land use changes have a
far bigger effect on ecosystem services and biodiversity than do changes in urban land use.
6
See http://www.naturalcapitalproject.org/InVEST.html. Accessed on March 30, 2011
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NATURAL RESOURCES AND AGRICULTURAL PRODUCTIVITY 39
WATER, AGRICULTURAL PRODUCTIVITY,AND ENVIRONMENTAL SERVICES7, 8
Peter G. McCornick, Duke University
Peter McCornick stated that food security is inherently dependent on the availability of
water resources, whether it is reliable rainfall (green water) or irrigation from surface or
groundwater sources (blue water). Competition for water from urban areas, industry and higher
value agricultural products will require that lower value, staple crop production rely more
heavily on rainfall or depend increasingly on less reliable blue water sources or both. Projected
population growth, expanding demand for a diet higher in animal products and fish, and the
increased need for non-food crops, including those for bioenergy, will continue to increase the
demand for water from agriculture. McCornick noted that the quantity of water from rainfed and
irrigated sources required by the agricultural sector is expected to as much as double by 2050,
further disrupting ecosystems.
Agricultural Water Productivity
To achieve food security and yet mitigate the negative effects on water resource systems
requires that water productivity be increased. However, saving water is not enough if there is not
a system for allocating it appropriately to achieve both productivity objectives and distributional
objectives. Therefore, effective governance systems and institutions must be developed. Not all
water apparently saved can be reallocated. Moreover, McCornick stated that effective
governance mechanisms are required to reallocate any gains that are made.
Trade-offs and Scale
McCornick explained that the rice-wheat systems in the Indus and Ganges basins provide
an example of intensified use, trade-offs, and unintended consequences. The yields in the
relatively water short Punjab portion of the basin are already high. Efforts to improve water
conservation in this area through various water resource conservation technologies (i.e. zero
tillage for wheat, direct seeding, bed planting, laser land leveling and crop residue management)
improved the field level water productivity. However, this “saved” water at the field scale
resulted in the expansion of irrigated crop-land in the immediate area, while the available supply
downstream declined highlighting the potential for unintended tradeoffs, especially critical in
increasingly water scarce basins in the developing world, such as the Indus.
Food security is a function of water security, especially in terms of water availability and
reliability. Disrupting this relationship are flood and drought events, which are expected to
become more frequent and severe as agricultural production expands and intensifies in flood
7
Prepared in collaboration with David Molden, Deputy Director General of Research, International Water
Management Institute, Colombo, Sri Lanka.
8
The presentation is available at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_060826,
presentation by Peter McCornick (February 16, 2011).
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40 A SUSTAINABILITY CHALLENGE: FOOD SECURITY FOR ALL
prone areas, while other regions suffer from a paucity of rainfall. Climate change further
complicates the situation. Decision making related to food security must carefully consider water
resources, especially to identify regions where there is the opportunity to increase agricultural
productivity without further stressing water resources (i.e., more crop-per-drop). McCornick
noted that this is especially critical in an increasing number of major agricultural producing
areas, where water is already relatively scarce. While most experts are optimistic that there is
scope for water productivity gains, such gains are difficult to realize and require a holistic view
of water management. Water allocation and reallocation processes are required in addition to
farm scale practices to realize gains of water productivity. To mitigate these consequences, an
essential tool in food security enhancement is accounting for water resources and management,
including actual water use in irrigated and rainfed areas, and the impact on available water
resources downstream. Unfortunately, many of these challenged regions are relatively data
scarce, the quality of information that does exist varies, and many of the data sets have been
developed as part of specific projects and are often not accessible at the national and sub-national
scales, which are crucial to water related decision making. Fortunately, technological advances
are presenting opportunities to better assess crop water use and groundwater levels.
GENERAL DISCUSSION
Hartwig de Haen began the discussion by questioning the extent to which agricultural
productivity must be increased in order to meet increases in population and food demand by
2050. He suggested that some of the assumptions underlying the projection that would require a
70 percent increase in production of food and feed would depend on other factors and drivers of
total future need for agricultural commodities. For example, he questioned whether future food
consumption trends will include increasing shares of animal protein as in recent years, whether
the amount of crops used for non-food uses such as biofuels will continue to grow, and whether
levels of post harvest losses and excessive food use will continue. He suggested that scenarios
should also be considered to explore the implications if these assumptions shifted: The required
production increases could be lowered, and the stress on natural resources could be reduced. Bill
Jury encouraged the group to consider long term demographics changes, such as increases in
urban populations in attempting to assure sufficient food supplies where they are needed.
Phil Pardey noted that the discussion on metrics for poverty and food security was
retrospective, not spatial and not forward looking, whereas the discussion on agricultural
productivity was forward looking and spatial.
COMPOSITE INDICATORS FOR SUSTAINABLE PRODUCTION
The panel examined composite indicators for sustainable production and natural resource
use and reviewed their use in promoting sustainable practices and in providing information to
consumers and policy makers.
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NATURAL RESOURCES AND AGRICULTURAL PRODUCTIVITY 41
OVERVIEW OF METRICS AND INDICATORS, DIFFERENT APPROACHES, AND
STRENGTHS AAND WEAKNESSES9
Greg Thoma, University of Arkansas
Greg Thoma provided a brief description of some of the agricultural sustainability
metrics currently available. He explained that sustainable agriculture can be defined as (a)
meeting the needs of the present while enhancing the ability of future generations to meet needs,
(b) increasing productivity to meet future food demands, (c) decreasing harmful effects on the
environment, (d) improving human health, and (e) improving the social and economic well-being
of agricultural communities.10 However, the definition is not tied to any specific metrics and
therefore does not provide a basis for action. He suggested that it is necessary to measure the
outcome of agricultural production in order to reduce environmental impacts. He identified a set
(not exhaustive) of variables critical to understanding agricultural systems, which are listed in
Table I 3-2.
TABLE I 3-2 Examples of Agricultural Sustainability Indicators
Category Emissions Drivers
Water Quality Nutrients Ammonia Livestock:
Sediments Metals Manure management & application
Pesticides Hormones Storm water management
Antibiotics Pathogens Land management (tillage, etc)
Crop protection and fertilization
Water Use Groundwater scarcity Livestock:
Reduced stream flows impact aquatic Drinking water and facility maintenance
habitats Irrigation
Particulate matter (10 & 20)
Air Quality Manure management
Odor Animal emissions
Ozone precursors Combustion
Greenhouse gasses
Land Use / Land occupation and conversion Land management
Biodiversity Habitat degradation / fragmentation (Tillage, riparian zone management, etc.)
SOURCE: Presentation by Greg Thoma, University of Arkansas, February 17, 2011.
Thoma then explained that these metrics need to be built into a framework that will help
in understanding the broader agricultural system as well as impacts and trade-offs. One such
framework or tool is life cycle assessment. This allows us to (a) think broadly from cradle to next
life; (b) think deeply about the impacts and endpoints; (c) think quantitatively throughout the
9
The presentation is available at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_060826,
presentation by Greg Thoma (February 17, 2011).
10
As defined by the Keystone Alliance: Field to Market.
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42 A SUSTAINABILITY CHALLENGE: FOOD SECURITY FOR ALL
supply chain, accounting for inputs, outputs, and emissions; and (d) think comparatively to
understand expectations and make a positive change. He noted that life cycle assessment is a
useful but far from perfect tool, in part because it does not yet include spatial or temporal
dynamics very well. He mentioned some newer tools, such as InVEST, that can assess the
impacts of ecosystem services, but those methods are not yet ready for incorporating into life
cycle assessment
Thoma provided a brief overview of some ongoing efforts to develop sustainability
metrics, sustainability indicators, and software tools (Box I 3-1).
In conclusion, Thoma emphasized that sustainability metrics should be outcome based
and technology neutral so that creative innovators can do whatever makes the most sense in their
specific location. Life cycle assessment is a useful tool in that it provides information and
understanding, enabling engagement of procurement officers and consumers so that market
signals and incentive can be communicated to farmers and other primary producers.
BOX I 3-1
Ongoing Efforts
Sustainability Metrics (Quantitative)
• Field to Market—The Keystone Alliance for Sustainable Agriculture: Focuses on
commodity agriculture; metrics are outcomes based and technology neutral; natural and
regional in scale.
• Stewardship Index for Specialty Crops: Focuses primarily on vegetables and fruits; metrics
are outcomes based and technology neutral; regional and local in scale.
• Solutions from the Land: Focuses on linking crop, forestry, and conservation land-
management; metrics into a harmonized approach; sponsored by the United Nations
Foundation, Conservation International, the Nature Conservancy, and the Farm
Foundation.
Sustainability Indicators (Qualitative)
• Unilever Sustainable Agriculture Code: Mandatory program for Unilever agriculture
suppliers; for example, it requires recordkeeping for pest and nutrient management; some
simple metrics are included.
• SAI Platform: Focuses specifically on agriculture; provides guidance on best management
practices; more practice than outcomes driven.
• People 4 Earth: Broadly looks at supply chains; uses more than 300 qualitative questions
that span sectors other than agriculture.
Software Tools
BASF Eco-Efficiency Analysis; GaBi, SimaPro, SALCA (Swiss Agricultural Life Cycle
Assessment); carbon footprint calculators (e.g., Cool Farm Tool); Fieldprint Calculator (Field
to Market); Global Water Tool; InVEST; and HarvestChoice.
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NATURAL RESOURCES AND AGRICULTURAL PRODUCTIVITY 43
INDUSTRY PERSPECTIVE ON USE OF METRICS11
Jennifer Shaw, Syngenta
Jennifer Shaw noted that there is wide agreement that agricultural systems need to be
sustainable to ensure long-term food security. The challenge, she said, is in trying to define and
measure what this really means. For Syngenta, one of the most important sustainability
initiatives in North America is Field to Market (FTM), a diverse stakeholder group facilitated by
the Keystone Center in Keystone, Colorado. FTM represents organizations with a common
interest in focusing on sustainable outcomes for production agriculture. The philosophy behind
FTM is to (a) focus on a key set of outcomes, (b) establish science-based metrics for measuring
progress against those outcomes, and then (c) “let the chips fall where they may.” With respect to
technology, the initiative takes a neutral position, neither promoting nor obstructing it. The
presence or absence of a given technology is not the key. The important thing is the performance
of the whole system and the tool is being used to develop precise metrics to assess changes in
agricultural systems. For example, “How are we doing today, and are we heading in the right
direction?”
Field to Market Indicators of Sustainability
• Environmental Indicators
o Land Use
o Water Use
o Soil
o Energy
o Climate
o Water Quality
o Biodiversity
• Productivity Indicators
• Grower Economic Index
• Social Indicators
• Health Indicators
• Ability to Meet Global Demand
FTM has developed metrics for five of the environmental efficiency indicators listed
above (energy, water, climate change, soil and land use/productivity). These metrics are being
piloted in cropping systems across the United States. Syngenta has been part of this process.
11
© 2011 Syngenta Crop Protection, LLC 410 S. Swing Road, Greensboro, NC 27409. The presentation is available
at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_060826, presentation by Jennifer Shaw
(February 17, 2011)
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48 A SUSTAINABILITY CHALLENGE: FOOD SECURITY FOR ALL
Voeste closed his presentation by outlining key points. In his view, the fundamental
principle has to be science-based analysis. A holistic and multicriteria approach is necessary to
demonstrate the impact on all aspects of sustainability. Researchers cannot rely on a single
indicator or a small group of indicators. Instead, a comprehensive set of robust and relevant
indicators are essential, together with reliable and quality data sources. Otherwise, the study runs
the risk of drawing incorrect conclusions or conclusions that do not cover all the relevant aspects.
To correlate the used indicators, publicly acceptable weighting factors have to be used, and the
results need to be quantitative and replicable.
Voeste emphasized that the improvement of relevant indicators―used to assess and
monitor progress in sustainability―will be vital in the global effort towards sustainable food
security. Robust measurement and practical scenarios will facilitate governance and drive
appropriate change.
FOOD SECURITY AND THE ENVIRONMENT
Jason Clay of the World Wildlife Fund set the stage for this session by stating that in the
next 40 years (i.e., by 2050), we will have to produce as much food as has been produced in the
last 8,000 years, and we are already exceeding the carrying capacity of the planet’s resources. He
noted that water is a critical concern going forward and that we need to find ways to address
increasingly scarce and variable water resources. Agriculture is also a large polluter (air, water,
and greenhouse gas emissions), which has more negative impacts on the planet than any other
human activity. He suggested that another noticeable factor is food waste—from the farm level
to consumers and beyond. Therefore, one of the most efficient ways to increase food availability
is to reduce waste. Clay also suggested that in this context, nature, not government, is the single
largest source of subsidies for agriculture. Furthermore, we need to account for environmental
externalities in costs and prices to send the right signals to producers and consumers. Finally,
Clay suggested that whatever the sustainability challenges have been to date, they will increase
significantly by 2050, when we have more than 9 billion people, with an average of 2.9 times as
much income, a doubling in consumption, and an increase in the consumption of animal protein.
This is the challenge going forward.
FOOD SECURITY AND THE ENVIRONMENT: FOOD SECURITY AND LAND
CROPPING POTENTIAL14
Jonathan Foley, University of Minnesota
Jon Foley began by emphasizing the role of agriculture on the planet, noting that about 40
percent of our global land area, 70 percent of our global water withdrawals, and 30 percent of
our greenhouse gas emissions come from land use and agriculture. It is also the single largest
driver of biodiversity decline. Therefore, it will be a major challenge to meet future food
demands while at the same time minimizing environmental impacts.
14
The presentation is available at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_060826,
presentation by Jon Foley (February 17, 2011).
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NATURAL RESOURCES AND AGRICULTURAL PRODUCTIVITY 49
Foley noted that there are two ways to meet these growing demands: expand the area
under production that grows food or intensify production per unit area of land (or both). Each has
serious environmental consequences. Expansion has significant implications for carbon, climate
change, and biodiversity. Intensification, on the other hand, requires the increasing use of water
resources, nutrients, pesticides, and fossil energy.
Foley described the Global Landscapes Initiative,15 based at the University of Minnesota,
which has developed approaches to examine these environmental implications and trade-offs.
The initiative provides spatial data on yields, fertilizer use, and irrigation rates of more than 175
crops. Foley’s presentation also focused on global production patterns for maize and wheat,
suggesting potential areas for agricultural expansion and intensification. He noted that further
cropland expansion is possible, but that many of the most likely areas are in the tropics or other
sensitive ecosystems, often with lower rates of productivity, so that carbon debt and the
biodiversity implications are enormous (Figure I 3-5).
current potential
croplands croplands
FIGURE I 3-5 Further expansion is possible.
SOURCE: Presentation by Jon Foley, University of Minnesota, February 17, 2011. Ramankutty et. al.
2002.
The map in Figure I 3-6 shows maize yields around the world to help identify areas
where more intensive cultivation could result in large productivity gains. The green areas are
places where close to maximum yields have been achieved (e.g., U.S. Upper Midwest and
Spain). In many places (colored yellow and brown), productivity could be increased by 25–50
percent without genetic improvement. He singled out Eastern Europe as a region with significant
potential for increased yields with improved management and infrastructure. Current production
is now just 25 percent of what would be projected based on its climate and soils.
Foley identified water and nutrient availability as the most significant short term factors
limiting production growth. Over the longer term, genetic improvements would be necessary.
15
See http://environment.umn.edwateru/gli. Accessed on June 6, 2011.
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50 A SUSTAINABILITY CHALLENGE: FOOD SECURITY FOR ALL
FIGURE I 3-6 Maize yield attainment.
SOURCE: Presentation by Jon Foley, University of Minnesota, February 17, 2011. Data from Mueller et.
al., in preparation.
In conclusion, Foley noted that freezing the footprint of agriculture; sustainably
intensifying land; optimizing the trade-offs between yield, water, and nutrients; and dramatically
improving the efficiency of the entire food system will be important steps. He emphasized the
need not only to look at food production as an end point but also to look at the net nutritional
contribution resulting from our agricultural practices.
THE ENERGY AND CARBON CONUNDRUM IN SUSTAINABLE AGRICULTURAL
PRODUCTION16
Paul Vlek, University of Bonn
Paul Vlek noted that growth in population and income in the developing world is driving
an increase in demand for food and agricultural production, calling for more land to be converted
or existing agricultural land to be used more intensively. This pressure has led to an increase in
land dedicated to agriculture in its various forms of around 20 percent over the last 40 years of
the past century with more than 50 percent of the tropical regions suffering from land
degradation and half of this area also showing serious soil degradation. Projections show that
16
The presentation is available at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_060826,
presentation by Paul Vlek (February 17, 2011).
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NATURAL RESOURCES AND AGRICULTURAL PRODUCTIVITY 51
another 20-30 percent of the original biomes in the tropics will be converted to agricultural land
by the middle of this century. As a result of land conversion it is estimated that about 2,250 106
metric tons of carbon dioxide (CO2) are emitted in the tropics alone. Thus, land conversion is an
environmentally costly means of securing food for a growing population.
Since the early 1960s, agricultural intensification has been an increasingly important
means for meeting food demand. In fact, Vlek stated, this approach is credited with sparing 1.1
billion ha of land that would have been converted if intensification options had not been
available. However, intensification of agriculture has been based largely on the deployment of
fossil energy in the sector. As annual primary energy use worldwide climbed from 9,000 to
10,000 106 toe17 during the 1990s, fossil energy use in agriculture went up from 197 to 222 106
toe, with most of that increase occurring in Asia. As agricultural systems become more intensive,
the energy efficiency of these systems decreases. As a result, the United States and Europe
produce 1.1 and 1.7 calories of food, respectively, for every calorie of fossil energy used,
whereas this ratio is nearly 5 in developing countries. If human energy is taken into account, the
efficiency of transforming energy into food calories is widely different, varying from 16.5 for
mixed root-crop-based systems in New Guinea to 1.3 for intensive rice cultivation in Surinam.
Thus, intensification has led to a great dependence of agricultural production on fossil fuels, a
rather disconcerting dependency when sustainability of agriculture is increasingly called for,
given the finite amounts of fossil fuels. The annual CO2 emission associated with this fossil
energy use is estimated to amount to 200 106 t, or one-tenth of what is emitted as a result of land
conversion, two-thirds of it associated with fertilizer use and one-third associated with the use of
mechanization. Thus, though less costly in greenhouse gas emissions, the long-term prospects of
relying on fossil energy for food production are risky.
Vlek explained that, overall, the contribution of agricultural operations to greenhouse gas
emissions is fairly small. It is the clearing of native ecosystems for agricultural use in the tropics
that is the largest (non-fossil fuel) source of CO2 input to the atmosphere. The use of farm
machinery, irrigation, fertilization, and chemical pesticides amounts to merely 4 percent of
commercial energy use in developing countries. Of this, 70 percent is associated with the
production and use of chemical fertilizers. In the absence of fertilizer use, the developing world
would have converted even more land for agriculture, most of which is completely unsuitable for
long-term cultivation. The dynamics of land appropriation by agriculture and pastures is driven
by increasing food demand, but also by the loss of productive land due to degradation. The need
to curtail encroachment on new, often less suitable land comes at a great cost, both in loss of
ecosystem services and CO2 emission, and should be avoided. However, the land that is
threatened to be abandoned due to degradation may make a contribution in mitigating
greenhouse gas emissions. Current expectations are that reforestation on such land can sequester
large quantities of carbon to mitigate excessive emissions elsewhere. But any program that aims
to set aside marginal land for the purpose of sequestering carbon must do so without threatening
food security in the region. The best option to liberate the necessary land for carbon
sequestration would be the intensification of agricultural production on some of the better lands
by increased fertilizer inputs while, at the same time afforesting some of the non- or less-
productive land. The validity of this concept has been demonstrated in experiments in
Uzbekistan, where as much as 120 metric tons of carbon were sequestered over 4 years by trees
planted on highly salinized agricultural land.
17
Tons of oil equivalent.
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52 A SUSTAINABILITY CHALLENGE: FOOD SECURITY FOR ALL
Vlek explained that his calculations show that the sequestration of carbon through
afforestation far outweighs the emissions that are associated with the production of the extra
fertilizer needed to maintain agricultural output. Increasing the fertilizer use on cereals in the
developing world (excluding China) by 20 percent would offer an overall net benefit in the
carbon budget of between 80 and 206 106 t per yr−1, depending on the carbon sequestration rate
assumed for the re-growing forest. In those regions, where current fertilizer use is low, the
relative benefits are the highest, as yield response would not yet exhibit diminishing returns.
Thus, more land can be set aside without harming food security. In Sub-Saharan Africa, a 20
percent fertilizer increase, which amounts to 0.14 106 t of extra fertilizer, can liberate land to tie
up somewhere between 8 and 19 106 t of CO2 per year (average: 96 t CO2 per 1 t fertilizer). In
the Near East and North Africa, with a 20 percent increased fertilizer use of 0.4 106 t yr −1,
between 10 and 24 106 t of CO2 could be sequestered on the land that is set aside (40 t CO2 per 1
t fertilizer). In South Asia this is 22–61 106 t CO2 yr −1, with an annual additional input of 2.2 106
t of fertilizer (19 t CO2 per 1 t fertilizer).
In summary, Vlek said that modern agricultural production world-wide is fossil fuel
dependent and carbon intensive. There is a high demand for agricultural land, especially in
developing countries, but the cost in CO2 release in land conversion is substantial. The
alternative is intensification, which is cheaper in CO2 loading, but increases dependency on
limited fossil fuel supplies. Sequestration of carbon on marginal land with afforestation would
far outweigh the emissions associated with the production of the extra fertilizer (12 106 t yr-1). In
the long run, however, Vlek emphasized that alternative energy sources are needed to sustain
agriculture.
FOOD SECURITY AND THE ENVIRONMENT: ANIMAL PROTEIN PRODUCTION
IMPACTS AND TRENDS18
Judith L. Capper, Washington State University
Jude Capper stated that in 1800, each U.S. farm could produce only enough food to feed
one other family. In the wake of considerable improvements in efficiency and productivity, each
farmer currently produces, on average, enough food to feed 125 other people. However, there is
a global food crisis, with the number of food-insecure people in the world increasing from 820
million in 2004–2006 to 1,020 million in 2009 (FAO, 2009b). The global population is predicted
to increase to approximately 9.5 billion people by 2050. This will increase total food
requirements by 70 percent compared with today (FAO, 2009a), as a function of both population
size and the augmented demand for milk and meat protein resulting from more widespread
global affluence. If the present competition for energy, land, and water supplies continues,
Capper noted, resources available for agricultural production are likely to decrease concurrently
with increased population growth. The global livestock industries, therefore, face the challenge
of producing sufficient nutritious, safe, affordable animal protein to meet consumer demand,
using a finite resource base.
18
The presentation is available at http://sites.nationalacademies.org/PGA/sustainability/foodsecurity/PGA_060826,
presentation by Judith Capper (February 17, 2011).
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NATURAL RESOURCES AND AGRICULTURAL PRODUCTIVITY 53
Sustainability is defined by the U.S. Environmental Protection Agency (U.S. EPA, 2010)
as “meeting society’s present needs without compromising the ability of future generations to
meet their own needs.” Capper noted that popular perceptions of sustainable agriculture are often
directed towards extensive low-input: low-output systems or systems that supply only the local
geographic area. This is reinforced by the growing trend within the media and Internet sites of
promoting an agrarian idyll of a population growing their own food in back yards or through
community cooperatives. Although animal proteins are considered as staple foods in many diets,
concern over the perceived environmental impact of conventional animal production may
threaten social license to operate in the future.
In any agricultural or industrial sector, improving productivity allows system fixed costs
to be diluted out over greater units of production, thus reducing the economic cost per unit. The
same concept can be applied to environmental costs, with carbon, the fundamental unit of energy
in living systems, as the currency. Capper explained that all animals require a basal daily
quantity of feed nutrients to maintain vital functions and minimum activities (maintenance
requirement). This can be considered to be the fixed cost of animal production that must be met
for every animal within the population. The level of animal protein production (milk yield,
growth) then determines the additional variable costs of the system. Nutrient energy use is a
valid proxy for natural resource use (land, water, fossil fuels) and greenhouse gas emissions.
Management practices that improve efficiency reduce the size of the animal population required
to produce a set quantity of animal protein and thus decrease the total associated maintenance
nutrient requirement, and will therefore reduce resource use and waste output per unit of food
produced (Table I 3-3).
Proof of this concept is demonstrated by the improvements in efficiency seen in the U.S.
dairy industry over the past 60 years. As described by Capper et al. (2009), the size of the U.S.
dairy herd peaked in 1944 at 25.6 million cows, with a total milk yield of 53.0 billion kg
produced through an extensive pasture-based system. By comparison, the 2007 dairy herd
contained 9.2 million cows producing 84.2 billion kg of milk. The four-fold increase in milk
yield per cow and consequent improvement in efficiency was facilitated by improvements in
management, nutrition, and genetics. Analyzing the environmental impact of the U.S. dairy
industry in 1944 compared with 2007 revealed that to produce an equivalent amount of milk,
only 21 percent of the dairy population (lactating cows, dry cows, heifers, and bulls), 23 percent
of the feedstuffs, 10 percent of the land, and 35 percent of the water were required, and only 24
percent of the manure was produced. Consequently, the total greenhouse gas emissions (carbon
footprint) per unit of milk were reduced by 63 percent, and the carbon footprint of the entire
dairy industry was 41 percent lower in 2007 compared with 1944.
Productivity has also improved substantially in the U.S. beef industry, with average beef-
carcass yield per animal increasing from 274 kg in 1977 to 351 kg in 2007 (USDA, 1978;
USDA/NASS, 2008). Management advances over this time period facilitated an increase in
growth rate, reducing the total days from birth to slaughter and thus the total maintenance
resource cost and waste output associated with beef production. Between 1977 and 2007,
increasing growth rate meant that the age at slaughter was reduced from 609 days to 485 days. In
combination with the increased beef yield per animal, this reduced animal numbers by 30
percent, feed use by 19 percent, water use by 14 percent, land use by 34 percent, manure
production by 20percent, and the carbon footprint per unit of beef by 18 percent (Capper,
2010b).
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54 A SUSTAINABILITY CHALLENGE: FOOD SECURITY FOR ALL
The FAO (2006) concludes that it is essential to continue to intensify livestock
production in order to maintain the efficiency gains that improve environmental sustainability.
By contrast, consumers often assume that extensive, pasture-based beef systems where cattle are
finished on grass are more environmentally friendly than conventional corn-based systems. It is
important to note, Capper said, that between one-half and two-thirds of conventional beef
animals’ lives are spent on pasture and that intensive corn-based finishing only occurs in the
final growth period within the feedlot. Growth rates are considerably lower in animals finished
on grass, and it is difficult to achieve high slaughter weights; therefore, grass-finished cattle are
usually slaughtered at around 486 kg at 679 days of age, compared with 569 kg at 453 days of
age in a conventional system (Capper, 2010a). As a consequence of the reduced slaughter
weight, 4.5 total animals (slaughtered animals plus the supporting population required to produce
calves for rearing) are required to produce 363 kg of beef carcass in the grass-finished system
compared with 2.6 total animals in the conventional system. When combined with the increased
time required to grow animals to slaughter weight, this increases the carbon footprint per 363 kg
of beef by 74 percent, land use by 83 percent, and water use by 326 percent (Capper, 2010a).
TABLE I 3-3 Productivity Improvements and Associated Impacts on Resource Use and Waste
Management in U.S. Animal Protein Production
Protein System Efficiency Improvement Impacts
Dairy Increased milk yield To produce an equivalent amount of animal
Increased component (fat and protein) yield protein from an improved system compared
with an unimproved system:
Beef Increased slaughter weight
Smaller total animal population
Increased growth rate
- Productive animals (lactating, growing)
Reduced time from birth to slaughter
- Supporting population
Swine Increased litter size Reduced total maintenance requirement
Increased number of litters per year Reduced resource use per unit of food
Reduced time from birth to slaughter Reduced waste output per unit of food
Reduced greenhouse gas output per unit of
food
Poultry Reduced mortality
Increased slaughter weight
Reduced time from birth to slaughter
Compared to ruminant production, swine and poultry industries are generally considered
to be less environmentally threatening to climate change, because monogastric animals produce
considerably less enteric methane than ruminants. Nonetheless, given the increase in poultry and
swine consumption predicted to occur from now to 2050, further efficiency improvements are
necessary within these industries to continue to reduce overall environmental impact. As shown
in Table I 3-3, improving sow productivity (i.e., litter size, number of litters), animal growth
rates, poultry mortality, and slaughter weights minimizes losses within the system, thus reducing
the size of the total animal population, the resources required, and the waste output from
producing a set quantity of animal protein.
The challenge of producing more animal protein to fulfill human population requirements
while minimizing resource use and waste output is not confined to future scenarios, Capper
explained. A recent FAO report on greenhouse gas emissions from global dairy production
differentiated the results by region and demonstrated a decrease in the carbon footprint per kg of
fat and protein-corrected milk at the farm gate for industrialized nations (1-2 kg CO2-equivalent
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NATURAL RESOURCES AND AGRICULTURAL PRODUCTIVITY 55
per kg milk) compared with developing areas (3-5 kg CO2-equivalent per kg milk). When carbon
footprint data are compared with the underlying data on regional milk production, a negative
association is shown; that is, as milk production per cow increases, carbon footprint per unit of
milk decreases. In 2007 the Chinese government announced that the human recommended daily
intake of dairy products should be increased from 100 to 300 g. Given the size of the Chinese
population, this would require an additional 65 million dairy animals at current daily milk yields
(11 kg per day). If productivity was improved to that of the average U.S. dairy cow (29 kg per
day), this would still require an increase in the dairy population, yet this increase would be
confined to 23 million animals with concurrent comparative reductions in total maintenance
requirements, resource use, and greenhouse gas output.
Debate continues as to the most suitable metric for assessing the sustainability of animal
protein production. Various possibilities exist, including resource use per unit of food (e.g., beef,
milk, cheese), acre of land or gallon of water; calories or protein output per acre; income per unit
of food; labor per acre, etc. The purpose of the animal agriculture industry is to produce animal
protein; therefore, it seems appropriate to use food output as a metric, yet differing regions may
have environmental challenges that bring other metrics (e.g., output per unit of water in drought-
stressed areas) into play. Capper noted that it is important to recognize that there is no “one-size-
fits-all” management practice or system to reduce environmental impact. As the FAO (2010)
report demonstrates, less-developed countries reliant on extensive production have increased
greenhouse gas emissions per unit of milk, yet the economic and social value of livestock
ownership is considerable. Capper emphasized that to move the global livestock industry further
towards sustainability, it is necessary to consider the balance between environmental, economic,
and social indexes.
The livestock industry faces a considerable challenge in producing sufficient animal
protein to feed the growing population while continuing to improve sustainability. As
demonstrated by improved efficiency in the U.S. livestock industry over the past 60 years, this
challenge may be partially met by making productivity gains that reduce resource use and cut
greenhouse gas emissions from livestock production. However, Capper noted, the metrics by
which this is assessed may differ between systems, just as the management practices put into
place to improve productivity will vary widely between regions. Rather than focusing on one
single metric, true sustainability within the livestock industry can only be achieved by a balance
between environmental impact, economic viability, and social responsibility.
GENERAL DISCUSSION
Following the presentations, participants asked for clarification on some of the
information. Emmy Simmons started the discussion by asking how the farm level analyses
described by Shaw and Voeste could be scaled up for use by policy makers. Greg Thoma said
that this was an important issue and that the Sustainability Consortium was building a modeling
infrastructure that uses linkages with other efforts, such as Field to Market, which would allow
the aggregation of farm level analyses to regional or national levels. Steve Polasky suggested
that it would be useful to link these farm level models to the life-cycle work being done under
InVEST as well as to the spatial modeling done through HarvestChoice. Many participants
voiced their support for this idea, but Thoma said that there remain challenges in doing this. For
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56 A SUSTAINABILITY CHALLENGE: FOOD SECURITY FOR ALL
example, it is difficult to calculate water sustainability along a supply chain that includes both
water stressed and nonstressed areas. Hartwig de Haen asked how the indicators being developed
related to those used in the Millennium Ecosystem Assessment. This led to discussion about the
need to tailor indicators to specific locations. For example, a bird index may be a useful measure
of biodiversity in the United States or Europe, but probably not in many other parts of the world.
Finally, it was noted that indicators related to the sustainability of livestock production were
much less well developed than those for other agricultural products.
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