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156
JOURNAL OF SOIL AND WATER CONSERVATION
MARCH/APRIL 2016—VOL. 71, NO. 2
W. Richard Teague is a research ecologist at Tex-
as A&M AgriLife Research in Vernon, Texas, and
Department of Ecosystem Science and Manage-
ment, Texas A&M University, College Station,
Texas. Steve Apfelbaum is a consulting ecol-
ogist with Applied Ecological Services, Inc. in
Brodhead, Wisconsin. Rattan Lal is a research
scientist in the School of Environment and Nat-
ural Resources at The Ohio State University in
Columbus, Ohio. Urs P. Kreuter is a socio-econ-
omist in the Department of Ecosystem Science
and Management at Texas A&M University,
College Station, Texas. Jason Rowntree is a re-
search scientist in the Department of Animal
Science at Michigan State University in East Lan-
sing, Michigan. Christian A. Davies is a research
scientist with Shell International Exploration
and Production Inc., Shell Technology Center
Houston in Houston, Texas. Russ Conser is a
consulting engineer for Regenov8 Advisors in
Fulshear, Texas. Mark Rasmussen is director at
the Leopold Center for Sustainable Agriculture at
Iowa State University, Ames, Iowa. Jerry Hateld
is director at the National Laboratory for Agricul-
ture and the Environment, USDA Agricultural Re-
search Services (ARS) in Ames, Iowa. Tong Wang
is a resource economist at Texas A&M AgriLife
Research in Vernon, Texas. Fugui Wang is a
modeler with Applied Ecological Services, Inc. in
Brodhead, Wisconsin. Peter Byck is a professor
at the Wrigley GlobalInstitute of Sustainability
and Cronkit School of Journalism at Arizona State
University Tempe and Phoenix, Arizona.
The role of ruminants in reducing agriculture’s
carbon footprint in North America
W.R. Teague, S. Apfelbaum, R. Lal, U.P. Kreuter, J. Rowntree, C.A. Davies, R. Conser, M. Rasmus-
sen, J. Hateld, T. Wang, F. Wang, and P. Byck
Abstract: Owing to the methane (CH
4
) produced by rumen fermentation, ruminants are a
source of greenhouse gas (GHG) and are perceived as a problem. We propose that with appro-
priate regenerative crop and grazing management, ruminants not only reduce overall GHG
emissions, but also facilitate provision of essential ecosystem services, increase soil carbon (C)
sequestration, and reduce environmental damage. We tested our hypothesis by examining
biophysical impacts and the magnitude of all GHG emissions from key agricultural pro-
duction activities, including comparisons of arable- and pastoral-based agroecosystems. Our
assessment shows that globally, GHG emissions from domestic ruminants represent 11.6%
(1.58 Gt C y
–1
) of total anthropogenic emissions, while cropping and soil-associated emissions
contribute 13.7% (1.86 Gt C y
–1
). The primary source is soil erosion (1 Gt C y
–1
), which in
the United States alone is estimated at 1.72 Gt of soil y
–1
. Permanent cover of forage plants
is highly effective in reducing soil erosion, and ruminants consuming only grazed forages
under appropriate management result in more C sequestration than emissions. Incorporating
forages and ruminants into regeneratively managed agroecosystems can elevate soil organic C,
improve soil ecological function by minimizing the damage of tillage and inorganic fertilizers
and biocides, and enhance biodiversity and wildlife habitat. We conclude that to ensure long-
term sustainability and ecological resilience of agroecosystems, agricultural production should
be guided by policies and regenerative management protocols that include ruminant grazing.
Collectively, conservation agriculture supports ecologically healthy, resilient agroecosystems
and simultaneously mitigates large quantities of anthropogenic GHG emissions.
Key words: carbon sequestration—conservation agriculture—ecosystem services—green-
house gases—regenerative ecosystem management—soil erosion
Grasslands and savanna ecosystems
around the world coevolved with graz-
ing ruminants and re (Frank and
McNaughton 2002). While many of these
ecosystems have been converted to crop
production, others are not suitable for pro-
duction of commodities for direct human
consumption owing to their climatic,
edaphic, or topographic limitations. Rather,
they can be used by people for food and
fiber production only if the plant resources
are consumed by domestic or wild grazing
herbivores (Herrero and Thornton 2013).
Domesticated animals, notably cattle but also
sheep and goats in the most arid areas, are
the basis for many pastoral cultures, which
generally observe customs connecting them
to livestock in ways that have supported
their collective health and prosperity for
centuries (Herrero and Thornton 2013).
With appropriate management, grazers can
enhance critical ecosystem services (Janzen
2010; Teague et al. 2013)
Some scientists have suggested that reduc-
tions in global ruminant numbers could make
a substantial contribution to climate change
mitigation goals and yield important social
and environmental cobenefits (Ripple et al.
2014), but the value of such an option must
be assessed within the larger context of all
agricultural practices and geographic situa-
tions. We need to consider the broad context
of ruminants in semiarid to mesic pastoral
and agricultural ecosystems and how man-
agement in these different circumstances can
balance the need for agricultural products
without destroying our natural resource base.
Human survival is dependent upon the
delivery of critical ecosystem services, includ-
ing renewable resources, and the continued
effective functionality of the ecosystems that
provide these services (MEA 2005). Modern
technology has substantially elevated the
material wealth of most people in devel-
oped nations, but at the expense of healthy
ecosystems that provide the goods and ser-
vices upon which human survival ultimately
depends (IPCC 2013). Renewable natural
resources must be used in ways that prevent
their depletion and promote ecosystem resil-
ience for self-replenishment.
To ensure long-term delivery of eco-
system services, policies and management
protocols for agricultural production should
(1) support ecologically healthy and resilient
arable and pastoral ecosystems; (2) miti-
gate anthropogenic greenhouse gas (GHG)
emissions; (3) address environmental, social,
cultural, and economic complexity; and (4)
avoid unintended consequences of produc-
tion practices. Failure to address unintended
consequences in agriculture has contributed
to serious ecological problems, most notably
RESEARCH EDITORIAL
doi:10.2489/jswc.71.2.156
Copyright © 2016 Soil and Water Conservation Society. All rights reserved.
www.swcs.org 71(2):156-164 Journal of Soil and Water Conservation
157
MARCH/APRIL 2016—VOL. 71, NO. 2JOURNAL OF SOIL AND WATER CONSERVATION
increased GHG emissions, soil carbon (C)
loss, and topsoil loss.
The problems of many current tillage-based
cropping and feedlot-based livestock produc-
tion systems can be avoided by ecologically
sensitive management of ruminants in mixed
crop and grazing agroecosystems. The bene-
fits could include increased C sequestration,
improved soil nutrient cycling, increased
soil stability, enhanced watershed function,
increased production of healthy food, and
enhanced biodiversity and wildlife habitat
(Liebig et al. 2010; Delgado et al. 2011).
Our objective is to provide an analysis of
the cost-benefit trade-offs between livestock
and arable crop production within whole
agroecosystems. We outline the magnitude
of GHG emissions from key agricultural
components and practices and discuss how
domesticated ruminants can be used as a tool
to facilitate the delivery of essential ecosys-
tem services, notably soil C sequestration
and GHG emission reduction. We propose
that with appropriate regenerative crop and
grazing management, ruminants facilitate
the provision of essential ecosystem ser-
vices, increase soil C sequestration, reduce
GHG emissions, and reduce environmental
damage caused by many current agricultural
practices. We tested our hypothesis by exam-
ining biophysical impacts and the magnitude
of all GHG emissions from key agricultural
production activities from peer-reviewed
journal sources. This included comparisons
of arable- and pastoral-based agroecosystems.
Methods
We collected data from peer-reviewed liter-
ature to compare the relative contributions
of GHG emissions from major agricultural
sources (table 1). Global estimates were
obtained for domestic ruminants, mainly cat-
tle, and other livestock (Ripple et al. 2014) to
compare with emissions from crop produc-
tion, including tillage, fertilization, harvest,
and transport (Vermeulen et al. 2012), and soil
erosion (Lal 2003). This was followed by an
examination of peer-reviewed literature for
the different components of both arable- and
pastoral-based agroecosystems to determine
ways of reducing GHG emissions from these
sources and decreasing negative ecosystem
service impacts of current agricultural prac-
tices. Soil erosion was a large component of
emissions, and different methods and prac-
tices for reducing erosion were examined.
This included use of permanent land cover
with forage plants and cover crops that usually
include grazing ruminants to achieve ecosys-
tem service and livelihood goals.
We consider how grazing ruminants can
be managed to enhance the provision of
essential ecosystem services, increase soil C
sequestration, and reduce environmental
damage caused by many current agricultural
practices, and the degree to which they can
concurrently reduce GHG emissions from
agricultural ecosystems. We examined the
impact of the GHG footprint of grass-fed
and finished ruminants compared to being
fed grain-based diets.
To illustrate the potential of using rumi-
nants as grazers and conservation cropping
practices in agroecosystems to reduce net
GHG emissions, we examine different
scenarios of land management in North
America. Our first set of five scenarios (figure
1) compares current cropping and grazing
practice GHG impacts with 50% reduction
in ruminants, and different percentages of
grazing land managed with conservation
(adaptive multipaddock [AMP]) grazing.
The second set of five scenarios (figure
2) compares current cropping and grazing
practice GHG impacts with 50% reduc-
tion in ruminants and different percentages
of both conservation cropping and con-
servation grazing management using data
from the literature review of Delgado et al.
(2011) and Teague et al. (2011). The data
for conservation cropping is taken from the
literature reviews of Gattinger et al. (2012)
and Aguilera et al. (2013), who document
the benefits of using conservation cropping
practices referred to in the section on emis-
sion sources from agriculture. These sources
report the sequestration of extra C from
regenerative management of between –2
and –4 t C ha
–1
y
–1
(–0.89 and –1.78 tn C
ac
–1
yr
–1
) compared to current management
alternatives so we calculate GHG emission
mitigation by regenerative, conservation
grazing and cropping at –3 t C ha
–1
y
–1
(–1.2
tn C ac
–1
yr
–1
; figures 1 and 2).
These hypothetical scenarios are specula-
tive because of a paucity of data, but they do
represent an inclusive assessment of possible
terrestrial and atmospheric impacts result-
ing from key agricultural activities in North
America, using published peer reviewed
field data. Calculations and data sources for
these scenarios are presented in table 2.
Discussion
Emission Sources from Agriculture. Analysis
of key elements in the food supply-chain
lifecycle indicates that agriculture gener-
ates substantial amounts of GHG emissions
(Vermeulen et al. 2012). This, along with
other environmental damage caused by
agriculture (MEA 2005), indicates that the
production of food to meet global demand
comes at considerable environmental and
social cost. Since tillage-based farming began,
most agricultural soils have lost 30% to 75%
of their soil organic carbon (SOC), with
industrial agriculture accelerating these losses
(Delgado et al. 2011). In some areas, instead
of increasing food yields, high input agricul-
ture has led to a decrease in food production
due to the environmentally deleterious
effects on soils (Janzen 2010). It is important
to note that anthropogenic sources of GHG
emissions from intensive crop production
are independent from ruminants and would
be produced even if ruminant numbers were
reduced because food from nonruminant
Table 1
Estimates of global sources of greenhouse gas (GHG) emissions related to agricultural soil man-
agement including cropping practices, soil erosion compared to that of livestock (We present
the mean of ranges reported in the references cited).
Percentage of
human caused
Parameter Gt C y
–1
* emissions (%) Source
Total human caused emissions 13.57 Ripple et al. 2014
Cropping and fertilizer 0.86 6.3 Vermeulen et al. 2012
Farm and rangeland soil erosion 1.00 7.4 Lal 2003
Total soil management 1.86 13.7
Cattle 1.27 9.4 Ripple et al. 2014
Other ruminants 0.31 2.3 Ripple et al. 2014
Other livestock 0.39 2.9 Ripple et al. 2014
Total livestock production 1.97 14.5
*1 Gigaton (Gt) = 10
9
metric tons.
Copyright © 2016 Soil and Water Conservation Society. All rights reserved.
www.swcs.org 71(2):156-164 Journal of Soil and Water Conservation
158
JOURNAL OF SOIL AND WATER CONSERVATION
MARCH/APRIL 2016—VOL. 71, NO. 2
sources would be needed to compensate for
the diminished ruminant product supplies.
Globally, the GHG emissions from domes-
tic ruminants represent 11.6% (1.58 Gt C
y
–1
) of total anthropogenic emissions (table
1; Ripple et al. 2014; Vermeulen et al. 2012;
Lal 2003). In contrast, soil-associated losses
contribute 13.7% (1.86 Gt C y
–1
) of total
anthropogenic emissions with 46% (0.86 Gt
C y
–1
) resulting from crop production inputs,
including fertilizers, fuels, and pesticides, and
54% of the emissions (1 Gt C y
–1
) from wind,
water, and tillage erosion, and to a lesser extent
erosion caused by inappropriate grazing prac-
tices. Based on these estimates and assuming
no change in production practices, projected
impacts of agricultural practices on GHG
emissions are expected to increase as food
production increases to meet the demands of
a growing global population.
Soil erosion caused by current crop-
land management contributes directly to
increasing GHG emissions (Lal 2003). In the
United States, annual soil mass losses from
crop and grazing land (1.72 Gt soil y
–1
; Lal
2003) is three times greater than the com-
bined yields from corn (Zea mays L.; 0.36
Gt y
–1
), soybeans (Glycine max; 0.045 Gt y
–1
)
and hay (0.146 Gt y
–1
; USDA 2012). Unless
measures are taken to reduce soil erosion,
current agricultural practices are unsus-
tainable and are greater sources of GHG
emissions than ruminant livestock in these
agroecosystems (table 1).
Additionally, common tillage practices
and the application of inorganic fertilizers
and biocides have reduced soil surface cover
and decimated soil microbial communities
that control 90% of soil ecosystem function.
Collectively, these crop production inputs
have contributed to the degradation of phys-
ical, chemical, and biological properties of soils
(Bardgett and McAlister 1999; Leake et al. 2004;
Khan et al. 2007; Leigh et al. 2009; Mulvaney
et al. 2009; Czarnecki et al. 2013; Kimble et al.
2007). Declining microbial communities result
in reduction of nutrient concentrations and
availability in the remaining soil (Delgado et
al. 2011). The impact of these losses is exacer-
bated by excess amounts of nutrients applied
(i.e., inorganic fertilizers) for 17 of the world’s
major crops (West et al. 2014).
Intensification of agriculture continues to
increase surface water runoff, soil erosion,
and siltation of reservoirs. Under the anaer-
obic conditions in anoxic sediment deposits,
emissions of methane (CH
4
), nitrous oxide
(N
2
O), and ammonia (NH
3
) from water
bodies are 1 ± 0.2 Gt C y
–1
(Lal 2003) and
approach emissions from cattle at 1.27 Gt C
y
–1
(Herrero and Thornton 2013). The N
2
O
and CH
4
emissions emitted from the distur-
bance of continued tillage and erosion of
SOC from clay and silt clay loam soils have
been one of the primary sources of GHG
emissions, accounting for a large percentage
of all GHG emissions produced by modern
civilization (Lal 2003, 2004).
In addition to the negative impacts of
the increasingly industrialized production
of crops, there has also been considerable
degradation of rangelands, which comprise
approximately 40% of the global terrestrial
area (excluding Greenland and Antarctica).
As rangeland ecosystems constitute approx-
imately 25% of potential C sequestration in
global soils (Follett and Reed 2010), their
degradation also contributes to elevated
GHGs emissions, reduction of ecosystem
services, and increased desertification.
Historically, many rangelands have been
subjected to increasingly heavy continuous
grazing (CG) by livestock. This management
approach, which allows sustained access
to plants by grazing ruminants without an
opportunity for recovery between grazing
events, has been documented as contributing
to serious negative effects, such as depletion
of root biomass and carbohydrate reserves
in selectively grazed plants and reduction in
aboveground biomass productivity. Other
negative effects of poor grazing manage-
ment include impoverished herbaceous plant
communities, more bare ground, lower SOC
reserves, and increased soil erosion and com-
paction (Janzen 2010; Teague et al. 2013).
At landscape scales these changes have con-
tributed to lower surface water infiltration,
increased runoff and downstream flooding,
and reductions in water quality (Janzen 2010;
Teague et al. 2013). As with tillage agricul-
ture, the sediments from eroded grassland
soils also emit GHG when organic matter in
sediments enters anaerobic waterways. As the
health of the land declines, so too does the
health of the livestock and people dependent
on livestock.
Powerful reminders of the detrimental
impacts of many current industrial cropping
and grazing practices are the anoxic pol-
luted lower reaches of the Mississippi, the
dead anoxic zone in the Gulf of Mexico,
and the chronic demise of pollinators in
North American cropping areas (Turner and
Rabalais 2003; MEA 2005). Viable alter-
natives to the damaging impacts of current
agricultural management based on tillage
and high inputs of fertilizers, pesticides,
hormones, and medicines are offered by
ecologically sensitive regenerative manage-
ment with low inputs that build rather than
destroy the biological base of living ecosys-
tems (Pimentel et al. 2005).
Alternative management options to
reduce or eliminate negative impacts of many
current agricultural practices have been out-
lined by Delgado et al. (2011), Gattinger et
al. (2012), and Aguilera et al. (2013). These
include (1) changing plow tillage to no-till
(NT) cropping and using precision agri-
culture to moderate the rate and timing
of application of agrochemicals and water
(Hatfield and Venterea 2014); (2) diversifying
annual cropping systems to include legumes,
perennial crops, and forages in rotations; (3)
using cover crops in conjunction with row
crops; (4) reintegrating grazing animals back
into cropping systems; (5) using organic soil
amendments, such as cover crops, manure,
and biofertilizers; (6) reducing nitrogen
(N)-fertilizer use, changing the type of fer-
tilizer used (e.g., legumes, controlled-release,
and nanoenhanced fertilizers), and using
nitrification inhibitors; (7) applying biotic
fertilizer formulations that feed the soil
microbial systems and improve mycorrhizal
function, reducing N and phosphorus (P)
runoff and ground water losses (Hatfield
and Walthall 2014); and (8) improving graz-
ing management, converting marginal and
degraded cropland to permanent pasture and
forests, and restoring wetlands.
Livestock as Part of the Solution.
Ruminants grazing in rangeland or cultivated
forage agroecosystems are beneficial when
they are appropriately managed (Delgado et
al. 2011; Teague et al. 2013). Grazing ungu-
lates play key ecological roles in grasslands
and savannas, and can contribute positively
to numerous ecosystem services. Beneficial
effects could include increased water infil-
tration, improved water catchment, greater
biodiversity, increased ecosystem stability
and resilience, and improved C sequestra-
tion; all of which can help mitigate GHG
emissions (DeRamus et al. 2003). When
domestic ruminants are managed in a way
that restores and enhances grassland ecosys-
tem function, increased C stocks in the soil
will lead to larger and more diverse popu-
lations of soil microbes, which in turn leads
Copyright © 2016 Soil and Water Conservation Society. All rights reserved.
www.swcs.org 71(2):156-164 Journal of Soil and Water Conservation
159
MARCH/APRIL 2016—VOL. 71, NO. 2JOURNAL OF SOIL AND WATER CONSERVATION
Figure 1
Hypothetical North American net greenhouse gas (GHG) emission scenarios for: (1) current
agriculture; (2) current agriculture with 50% current ruminants; (3) current cropping and 25%
regenerative adaptive multipaddock (AMP) conservation grazing with current numbers of rumi-
nants; (4) current cropping and 50% AMP grazing with current numbers of ruminants; and (5)
current cropping and 100% AMP grazing with current numbers of ruminants.
0.7
0.5
0.3
0.1
–0.1
–0.3
–0.5
–0.7
–0.9
–1.1
–1.3
Net GHG emissions (Gt C y
–1
)
Legend
Livestock production Farm soil erosion Fertilizer and cropping
1 2 3
4 5
Figure 2
Hypothetical North American net greenhouse gas (GHG) emission scenarios for: (1) current agri-
culture; (2) current agriculture with 50% current ruminants; (3) 25% conservation cropping and
adaptive multipaddock (AMP) grazing with current numbers of ruminants; (4) 50% conservation
cropping and AMP grazing with current numbers of ruminants; and (5) 100% conservation crop-
ping and AMP grazing with current numbers of ruminants.
0.7
0.5
0.3
0.1
–0.1
–0.3
–0.5
–0.7
–0.9
–1.1
–1.3
Net GHG emissions (Gt C y
–1
)
Legend
Livestock production Farm soil erosion Fertilizer and cropping
1 2 3 4 5
to greater C sequestration, including CH
4
oxidation (Bardgett and McAlister 1999;
Teague et al. 2013; Jamali et al. 2014). With
livestock management focused on building
soil health, grazing animals can create C neg-
ative budgets, with more C entering the soil
than is emitted indirectly or via ruminant
emissions (Janzen 2010).
Combining crop rotation with live-
stock grazing can be particularly effective at
enhancing soil function and health (Delgado
et al. 2011). Crop production can be man-
aged to maintain permanent ground cover
through the rotation of forage and row crop
mixes, including cover crops, and legumes
to increase soil fertility by fixing N. Grazing
livestock can accelerate nutrient cycling
through the consumption and decomposi-
tion of residual aboveground biomass. For
example, sowing winter crops into perma-
nent summer growing pastures and using
crop rotation systems with forage crops and
grazing animals have been shown to signifi-
cantly reduce the damaging effects of many
current arable land management practices,
including soil erosion, loss of SOC, and
elevated GHG emissions, especially where
soil erosion potential is moderate to high
(Delgado et al. 2011).
Achieving the same soil health benefits
in pasture and rangeland-based livestock
production systems as in mixed rotational
cropping-livestock systems typically requires
a change in land management practice.
Ruminant production entirely from pastures
has been achieved most effectively, effi-
ciently, and economically using appropriate
regenerative grazing management (Delgado
et al. 2011; Janzen 2010; Teague et al. 2011,
2013; Gerrish 2004). Thus the most signif-
icant improvements can be achieved when
erosion-prone cropping systems are replaced
by permanent pastures maintained under
improved grazing management.
On rangelands, use of regenerative AMP
grazing management has been demonstrated
globally to be capable of reversing degrada-
tion processes associated with the widespread
practice of CG at high stocking rates (Teague
et al. 2011, 2013; Gerrish 2004). Regenerative
management uses a goal-oriented, proac-
tive, multipaddock grazing strategy focused
on restoring the ecological function and
productivity of degraded grasslands. The
approach uses short periods of grazing in any
given area and proactively adjusts postgrazing
forage residuals, recovery periods, and other
Copyright © 2016 Soil and Water Conservation Society. All rights reserved.
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160
JOURNAL OF SOIL AND WATER CONSERVATION
MARCH/APRIL 2016—VOL. 71, NO. 2
Table 2
Details of estimates to determine North American greenhouse gas (GHG) emissions due to current cropping and grazing management, current crop-
ping with reduced ruminants compared to using conservation cropping and regenerative adaptive multipaddock (AMP) grazing with current levels
of ruminants used for gure 1 and gure 2 (scenarios 3 through 5 assume stated percentage of land under conservation cropping and AMP grazing
with the remainder applying usual practices.).
Scenario (Gt C y
–1
)
Parameter 1 2 3 4 5
Current cropping with AMP grazing
Crop production (USEPA 2006; O’Mara, 2011) 0.083 0.083 0.083 0.083 0.083
Soil erosion* (Lal 2003) 0.14 0.14 0.109 0.077 0.014
Livestock production (Ripple et al. 2014; Vermeulen et al. 2012) 0.056 0.028 0.056 0.056 0.056
AMP grazing† 0 0 –0.198 –0.395 –0.790
Net livestock† 0.056 0.028 –0.142 –0.339 –0.734
Total 0.279 0.251 –0.050 –0.179 –0.637
Conservation cropping with AMP grazing
Crop production‡ (Gattinger et al. 2012; Aguilera et al. 2013) 0.083 0.083 –0.058 –0.199 –0.480
Soil erosion* (Lal 2003) 0.14 0.14 0.056 0.042 0.014
Livestock production (Ripple et al. 2014; Vermeulen et al. 2012) 0.056 0.028 0.056 0.056 0.056
AMP grazing† 0 0 –0.198 –0.395 –0.790
Net livestock 0.056 0.028 –0.142 –0.339 –0.734
Total 0.279 0.251 –0.143 –0.496 –1.200
*Soil erosion was considered to be 50% less with both AMP grazing and conservation cropping.
†–3 t C ha
–1
y
–1
(Delgado et al. 2011; Teague et al. 2011) for 263 × 10
6
ha grazing lands (UN FAO 2011).
‡ Conservation cropping at –3 t C ha
–1
y
–1
(Gattinger et al. 2012; Aguilera et al. 2013) for 160 × 10
6
ha (UN FAO 2011).
management elements as biophysical con-
ditions change (Teague et al. 2013; Gerrish
2004; Butterfield et al. 2006). Regenerative
AMP grazing has been successfully applied in
areas with annual rainfall ranging from 250 to
1,500 mm (9.8 to 59 in) and the best regen-
eration, ecosystem service and production
results (Teague et al. 2011, 2013) have been
achieved using regenerative management
protocols (Butterfield et al. 2006).
Such grazing management has resulted
in increased forage productivity, restoration
of preferred herbaceous species that were
harmed by previous grazing practices, and
increased SOC, soil fertility, water hold-
ing capacity, and economic profitability for
ranchers (Teague et al. 2011, 2013). Data
presented by Teague et al. (2011) of “across
the fence” comparisons in southern tallgrass
prairie in Texas, where AMP was applied
to areas previously degraded through pro-
longed CG, enable us to calculate an average
of 3 t C ha
–1
y
–1
(1.2 tn C ac
–1
yr
–1
) more C
sequestration in the top 90 cm (35.4 in) of
soil over a decade in AMP grazing compared
to commonly practiced heavy CG (table 2).
Research has also shown that AMP grazing
management led to higher herbaceous plant
cover and plant productivity; reduced bare
ground, erosion, and nonlivestock related
GHG emissions; and improved hydrologi-
cal processes (DeRamus et al. 2003). Where
regenerative grazing has been practiced
in semiarid and arid lands for some time,
ephemeral streams have reperennialized and
biodiversity has recovered to varying degrees.
Additionally, soil-building cool-season and
warm-season grasses, N fixing native legumi-
nous plant species, and even pollinators have
increased (National Research Council 2002).
The paleo record also provides evidence
that regenerative human management of
grassland agroecosystems can create a large C
sink to curb anthropogenic GHG emissions
(Retallack 2013). The coevolution of grass
and grazers over the last 40 million years
caused the global expansion of C-rich soils
in semiarid to semihumid grassland regions
covering approximately 40% of the global
land area. This likely induced global cool-
ing, decreased precipitation, and decreased
carbon dioxide (CO
2
) during the Oligocene,
Miocene, and Quaternary periods (Retallack
2013). Soil changes are believed to have
been caused by the large migratory, socially
organized, ungulate herds constantly mov-
ing and avoiding fouled grazing sites,
seeking water and nutrients, and respond-
ing to predation, fire, herding, and hunting
(Frank and McNaughton 2002; Teague et al.
2013; Butterfield et al. 2006). Grazing sel-
dom lasted long before the animals moved
to new feeding grounds, leaving the old
grounds with extended periods of recov-
ery from defoliation. The coevolved soil
microbes and fauna rapidly recycled nutri-
ents and enhanced soil structure to result
in more fertile, crumb-structured soils with
better infiltration and water holding capac-
ities that enhanced soil C levels (Teague et
al. 2013; Retallack 2013). In areas such as
Australia where sod grasses and native ungu-
lates did not coevolve, very few C-rich soils
developed, compared to areas such as Africa
and North America where such coevolution
did occur. However, after the settlement of
Australia by Europeans and the introduction
of sheep and cattle and associated pasture
improvements with introduced legumes,
earthworms, and dung beetles, C-rich soils
have been created where rainfall permitted.
Similarly, improved regenerative grassland
management in Australia has been shown to
increase soil C and enhance ecological func-
tion (Retallack 2013).
Regarding net ruminant-based enteric
CH
4
emissions, the C footprint of beef
cattle production solely from grassland is
exceeded by the amount of C sequestered
by the grasses and soil upon which they
graze. Data from the Northern Plains (Liebig
et al. 2010) report modest annual SOC
sequestration rates with conventional CG
management (–0.618 t CO
2equiv
ha
–1
y
–1
for
heavy stocking and –0.783 t CO
2equiv
ha
–1
y
–1
for moderate stocking [–0.250 tn CO
2equiv
Copyright © 2016 Soil and Water Conservation Society. All rights reserved.
www.swcs.org 71(2):156-164 Journal of Soil and Water Conservation
161
MARCH/APRIL 2016—VOL. 71, NO. 2JOURNAL OF SOIL AND WATER CONSERVATION
ac
–1
yr
–1
for heavy stocking and –0.317 tn
CO
2equiv
ac
–1
yr
–1
for moderate stocking]).
Overall enteric CH
4
was reported to be
0.484 and 0.176 t CO
2equiv
ha
–1
y
–1
(0.196
and 0.0713 tn CO
2equiv
ac
–1
yr
–1
), respectively,
indicating a negative GHG balance for both
conventionally grazed systems. However, as
noted previously, improved AMP grazing
management can result in an average SOC
sequestration rate of 11 t CO
2equiv
ha
–1
y
–1
(3 t
C ha
–1
y
–1
[1.2 tn C ac
–1
yr
–1
]) more than that
of heavily stocked CG (Teague et al. 2011).
With respect to global warming potential,
SOC is the largest determinant in the C
footprint of beef production from a forage
base managed to maximize C sequestration.
Most cattle produced in developed coun-
tries from conventional, continuously grazed
rangelands and forage-based grazing sys-
tems are finished for the marketplace on
high starch, grain-based feeds. Proponents
of this finishing method claim that, com-
pared to grass-finished beef production,
intensification of production through the
use of grain-based feeds results in lower
GHG emissions per kilogram beef produced
because it reduces the overall production
time to slaughter and enteric fermentation
during this time (Capper 2012). However,
this claim does not take into consideration
the full GHG emissions associated with
the production of grain-based feeds and
soil erosion. Not accounting for substan-
tial GHG emissions resulting from crop
production greatly underestimates GHG
output from feedlot-based beef production
(table 1). However, should grain produc-
tion be converted to regenerative practices,
this would diminish GHG production sub-
stantially (Gattinger et al. 2012; Aguilera et
al. 2013). Consequently, suitable modifica-
tion of agroecosystem production systems
and conversion to regenerative cropping
and AMP-based grass-finished livestock
would also increase the provisioning of other
important ecological benefits (DeRamus et
al. 2003) as outlined in the alternative sce-
narios below.
Producing grass-finished beef in AMP
management schemes obviates the need for
finishing animals on grain-based diets. This
switch reduces the C footprint of ruminant
production because of the elimination of soil
GHG emissions resulting from grain produc-
tion and associated soil erosion. Therefore,
beef production without grain inputs or
grain from regenerative cropping has the
potential to reduce fossil fuel inputs, GHG
emissions, and soil erosion, while improving
health and resilience of the agroecologi-
cal system as well as human health (Daly
et al. 2010). There has been a rapid increase
in demand for grass-fed beef (Herrero and
Thornton 2013) as many beef consumers
recognize that grass-fed and grass-finished
beef is better for both their health and the
environment. In addition, if crop production
currently used for animal feed and other uses,
such as biofuels, were instead used for human
food products, supplies would be increased
by 70%, thus providing sufficient resources
for an additional four billion people (West
et al. 2014).
Therefore, widespread conversion of
livestock-purposed cropland to a rotation
with perennial pasture or rangeland, such as
the integrated crop and pasture systems asso-
ciated with Australian ley farming systems
(Carberry et al. 1996), would be the most
advantageous option to reduce overall crop
and livestock-associated GHG emissions.
Consequently, we propose that rather
than reducing ruminant livestock to mitigate
climate change, producers should be encour-
aged to replace their current unsustainable
crop and livestock practices with regenera-
tive management practices. In both cropping
and grazing systems, soil management is the
key to optimizing ecological function and
reversing degradation caused by previous
management. If we do not manage to reverse
soil functional degradation, the damaging
effects on soils will decrease food production
potential, as noted by Janzen (2010). From
research and studying successful conservation
farmers, soil ecological function is main-
tained by using perennial plants rather than
annuals, managing for the most productive
plants, using diverse species mixes and cover
crops, leaving plant residue, eliminating till-
age damage, keeping the soil covered with
plant material and minimizing bare ground,
using organic soil amendments, reducing N
fertilizer use, and growing plants for the max-
imum number of days each year (Delgado et
al. 2011; Teague et al. 2011; Gattinger et al.
2012; Aguilera et al. 2013).
Alternative Net Greenhouse Gas Emission
Scenarios. In figure 1 we postulate five sce-
narios for land management changes to
reduce and ultimately reverse GHG emis-
sions associated with current cropping
practices while adopting regenerative AMP
grazing practices:
• Scenario 1 represents the estimated total
C emissions from soil erosion loss, cur-
rent tillage and fertilizer practices for crop
production, corn-finished livestock produc-
tion, and current CG management. It most
closely resembles the substantial C footprint
of the current agricultural practices.
• Scenario 2 represents the reduction of
ruminants by 50% from the current num-
bers as proposed by Ripple et al. (2014).
It has only a modest impact on total C
emissions from all agricultural activities.
• Scenarios 3, 4, and 5 represent adoptions of
best conservation management practices
in grazing on 25%, 50%, and 100%, respec-
tively, of land used in North America for
livestock production. These conservation
management practices include grass-fed
and grass-finished beef production using
AMP grazing management.
Similarly, in figure 2 we postulate five
scenarios for land management changes to
reduce and ultimately reverse GHG emis-
sions associated with both regenerative
conservation cropping practices and regen-
erative AMP grazing practices:
• Scenarios 1 and 2 in figure 2 are the same
as in figure 1.
• Scenarios 3, 4, and 5 represent adoptions
of best conservation management prac-
tices in both cropping and grazing on 25%,
50%, and 100%, respectively, of land used
in North America for crop and livestock
production. These conservation manage-
ment practices include zero till and crop
rotations with minimal inorganic fertilizer
use in crop production, and grass-fed and
grass-finished beef production using AMP
grazing management.
The application of these regenerative
conservation practices in crop and livestock
production systems to just 25% of the land they
occupy results in substantially less net C emis-
sion than reducing livestock by 50%. Applying
them to greater portions of agricultural pro-
duction land results in increasingly negative net
C emissions with application to all agricultural
land, potentially providing a significant C sink
to offset nonagricultural emissions.
These scenarios provide a set of testable
hypotheses that could direct future long-
term (at least 10 years) systems-based research
at the operating scale. Figure 3 presents a
schematic outlining the scenarios depicted in
figure 2. To date such research has been lack-
ing due to funding and logistical constraints.
These constraints have led to a plethora of
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JOURNAL OF SOIL AND WATER CONSERVATION
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short-term and small-scale crop and live-
stock production research, the results of
which frequently bear no resemblance to the
performance of best management practices
applied across the whole-systems operating
scale (Teague et al. 2013; Van der Ploeg et al.
2006). The principle reason for this discon-
nect is the lack of capacity for short-term
and small-scale research to address interac-
tions at the systems level; land management
lag effects; and both spatial and temporal het-
erogeneity of soils, vegetation, and livestock
impact and precipitation patterns at opera-
tional scales.
Development and Adoption of Regenerative
Management. To effect management changes
that will lead to a more sustainable future
it is vital to create government agricul-
tural policies that encourage the adoption
of regenerative GHG neutral, or possibly
GHG negative, agricultural practices. Such
policy changes should reward producers for
adopting and maintaining environmentally
sustainable management practices for both
crop and livestock production and discourage
the use of land management practices that
require high energy inputs and irrigation,
and that degrade soils, reduce biodiversity,
and increase GHG emissions.
At a minimum, policy changes should
encourage farmers to implement no-till
agriculture, more diverse crop rotations,
more perennial forages, greater biodiversity
in the form of cover crops between rota-
tions, regenerative grazing management, and
minimized nongrazing feeding of ruminants.
Such policies would lead to an expansion of
mixed agronomic systems that facilitate the
reintroduction of grazing animals as an ele-
ment of integrated food production versus
the government-incentivized monoculture
systems that are leading to the environmental
damage outlined in this document.
To operationalize such policies, it is
equally vital that leaders in farming and
ranching communities across the world
actively participate in developing workable
solutions and adaptive practices for food
production ecologically suited to local bio-
physical conditions (Herrero and Thornton
2013; Janzen 2010). Leading environmen-
tally conscious farm and ranch managers are
demonstrating how it is possible to achieve
desired environmental goals, while simulta-
neously improving livelihoods.
Knowledge gained from reductionist sci-
ence does not translate automatically into
producing desirable results from crop or
grazing agroecosystems, especially at water-
shed scales or across regions (Teague et al.
2013; Van der Ploeg et al. 2006). To be
meaningful, small-scale reductionist research
should be subsumed within complementary
whole-systems research. To achieve this, it
is imperative to work in collaboration with
farmers and ranchers who obtain superior
economic returns in different ecological
and cultural settings while simultaneously
improving the biophysical conditions of
their environments (Van der Ploeg et al.
2006). Finally, working to educate drivers
of change, from policymakers to the farm-
ing community, is essential to overcome the
complexity associated with GHG emissions
and overall impacts of ruminant livestock
and crop production.
Conclusions
Soil is a depletable resource, but produc-
tion of food for human consumption does
not have to deplete the soil. Cropping and
grazing practices that build SOC levels and
soil microbial communities and functions,
and that minimize soil erosion can result in
soils being a net sink for GHGs rather than
a major source of GHGs, as is currently the
case. Effective soil management provides
the greatest potential for achieving sustain-
able use of agricultural land under a rapidly
changing climate. Ruminant livestock are
an important tool for achieving sustainable
agriculture. With appropriate grazing man-
agement, ruminant livestock can increase C
sequestered in the soil to more than offset
their GHG emissions, and can support and
improve other essential ecosystem services
for local populations. Affected ecosystem
services include water infiltration, nutrient
cycling, soil formation, C sequestration, bio-
diversity, and wildlife habitat. Our assessment
suggests that increasing SOC globally within
food production systems will reduce the C
footprint of agriculture much more than
reducing domesticated ruminant numbers in
an effort to reduce enteric GHG emissions.
The simultaneous increase in production of
agricultural goods indicates that integrating
livestock into mixed agricultural systems
and grazing management to increase SOC,
biodiversity, and soil quality would enhance
resilience of soil and agroecosystems against
climate change and extreme events.
A primary challenge to the increasing
global demand for food is how to increase the
scale of adoption of land management prac-
tices documented to have a positive effect on
soil health. It is essential that scientists partner
with environmentally progressive managers
at sufficiently large scales to convert exper-
imental data on managed landscapes into
sound environmental, social, and economic
results that will provide regional and global
benefits. Rather than reducing ruminants
and encouraging destructive agricultural land
use by providing price subsidies and other
subsidies, rewarding regenerative agricul-
tural practices that focus on increasing soil
C and that lead to greater adoption by land
managers is essential to creating a robust,
resilient, and regenerative global food pro-
duction system.
Acknowledgements
We thank Doug Karlen (supervisory research soil scientist,
National Laboratory for Agriculture and the Environment,
USDA Agricultural Research Service, Ames, Iowa), John
Kimble (director [retired] USDA Natural Resource
Conservation Service-NSSC, Lincoln, Nebraska), Marcia
DeLonge (scientist, Union of Concerned Scientists, Cambridge
Massachusetts), and Henk Mooiweer (GameChanger leader
at Shell and Adjunct Professor Invention and Innovation at
Rice University, Shell Oil Company, Shell Technology Center
Houston, Houston, Texas) for comments and inputs to earlier
drafts of the manuscript.
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