Global agriculture is facing growing challenges at the nexus of interconnected food, energy and water systems, including but not limited to persistent food insecurity and diet-related diseases; growing demands for energy and consequences for climate change; and declining water resources, water pollution, floods and droughts. Further, soil degradation and biodiversity loss are both triggers for and consequences of these problems. In this commentary, we argue that expanding agroecological principles, tools, and technologies and enhancing biological diversity can address these challenges and achieve better socioeconomic outcomes. Agroecology is often described as multi- or transdiscplinary, and applies ecological principles to the design and management of agricultural systems through scientific research, practice and collective action. While agroecology has roots in the study of food systems, agricultural land use has many direct and indirect linkages to water and energy systems that could benefit from agroecological insights, including use of water resources and the development of bio-based energy products. Although opportunities from the science and the practice of agroecology transcend national boundaries, obstacles to widespread adoption vary. In this article, we therefore focus on the United States, where key barriers include a shortage of research funds, limited supporting infrastructure, and cultural obstacles. Nevertheless, simply scaling up current models of agricultural production and land use practices will not solve many of the issues specific to food related challenges nor would such an approach address related energy and water concerns. We conclude that a first critical step to discovering solutions at the food, energy, water nexus will be to move past yield as a sole measure of success in agricultural systems, and call for more holistic considerations of the co-benefits and tradeoffs of different agricultural management options, particularly as they relate to environmental and equity outcomes.

Introduction

New impetus for interdisciplinary research on food, energy, and water systems is emerging, driven by an increasing recognition that focus on gains in one specific area can inadvertently lead to losses in others, as well as by concerns about population growth, climate change, water resources, and deficiencies of the current food and agricultural system. As this research area develops, the scientific community can work to identify the most critical questions, tools, and approaches to cost-effectively uncover sustainable solutions. In this article, we propose that the field of agroecology is poised to effectively address these challenges, but we also highlight several obstacles that may need to be overcome to enable broader application of agroecological solutions.

A commonly used definition of agroecology is that it is “the science of applying ecological concepts and principles to the design and management of sustainable food systems” (Gliessman, 2014), and many authors have stressed the importance of defining agroecology more broadly as jointly a science, practice and social movement (Sevilla Guzmán et al. 2013). While definitions of agroecology vary (Montenegro de Wit and Iles 2016), we have interpreted that a core feature is that it entails a systems – based study of the agricultural system – from crop production to product use – and draws on the biophysical and social sciences to develop ecologically, economically, and socially sustainable agricultural practices. It is noteworthy that agroecology is often defined in terms of food systems, but that the field includes tools and perspectives that are highly relevant to agricultural systems more broadly, which are tightly linked to water and energy systems.

Agroecology involves a multi-disciplinary, and often a transdisciplinary, approach that can lead to solutions that serve the public good by simultaneously fostering food system productivity and resilience, reducing energy consumption and supporting bioenergy production, as well as conserving water resources (Kremen and Miles, 2012; Ponisio et al., 2015; Gliessman, 2014; Schipanski et al., 2016). Agroecology can be conceptualized as multi-disciplinary in its approach in addressing concurrent research disciplines; it should be noted further, however, that it is also transdisciplinary in that it incorporates but also elements of practice and collective action, which can enable the scaling of agricultural practices from individual farms to larger landscape-level change. As a result, there is growing recognition that an agroecological transformation is needed on a global scale (IPES–Food, 2016). Notably, more than four hundred scientists working in related fields, including experts from within and outside of the United States, have called for an increase in public funds to help support such a shift (Union of Concerned Scientists, 2017). While a move toward agroecological principles is needed globally, this commentary will focus primarily on opportunities, barriers, and motivations that are particularly germane within a U.S. policy context.

Agroecology and biological diversity for more resilient food, energy, and water systems

Industrial agricultural landscapes planted as large-scale monoculture systems, with either food or energy crops, have been linked to broad environmental and societal consequences. Such biologically simplified farming systems have been connected to water-related issues such as pollution and toxic algal blooms (Porter et al., 2015; Smith et al., 2015), and depletion of groundwater (Richey et al. 2015). At the same time, many of these systems are also prone to soil erosion and degradation (Montgomery, 2007; Veenstra and Burras, 2015), loss of pollinator species (Kremen et al., 2002), and the decline of rural communities (Francis et al., 2014), all of which could contribute to additional problems, such as a loss of system resiliency. One recent study supported this hypothesis regarding resilience, finding that higher-income countries that are more heavily reliant on large-scale monocultures had a greater yield deficit following extreme weather as compared to lower-income countries that likely include more diverse crops and management (Lesk et al. 2016). Thus, these industrial-scale landscapes of food and energy crops may be putting pressure on natural resources and socioeconomic systems in the interest of achieving potentially high productivity, but with unintentional losses resulting from low resilience. Increasingly, many of the agricultural practices used on these landscapes are also exacerbating current and future challenges by contributing substantially to greenhouse gas emissions and climate change risks, such as floods and droughts. Recent estimates indicate that agriculture is responsible for about 9% of U. S. (Environmental Protection Agency, 2015) and 11% of global emissions (Tubiello et al., 2015), respectively.

Despite growing evidence of weaknesses, biologically simplified agricultural landscapes have continued to expand in recent years, leading to overall declines in biodiversity in both croplands and grasslands (United States Department of Agriculture, 2005; Newbold et al., 2016). This expansion has been in part due to policies that incentivize such systems and reduce financial risk (Union of Concerned Scientists, 2016a). A good example of this in the United States that also demonstrates the tight linkages between food, energy, and water systems is the continued conversion of perennial grasslands into corn and soybean production for bioenergy. This trend intensified following the passage of the Renewable Fuel Standard in the mid-2000s and associated higher commodity prices (Wright and Wimberly, 2013; Lark et al., 2015). Importantly, in this case, policies that were intended to strengthen agricultural markets for rural communities have had mixed outcomes, associated with the High Plains Aquifer causing stress on local groundwater supplies (Scanlon et al. 2012). Even prior to this policy, however, increased U.S. Federal crop insurance subsidies (resulting from the 1994 Crop Insurance Reform Act) had reduced the financial risk of cultivating environmentally sensitive lands; these subsidies have been linked to disproportionately large unintended consequences such as nutrient loss and soil erosion (United States Department of Agriculture, 2006).

As a juxtaposition to the current model of bioenergy production, alternative crop systems developed through an agroecological approach that is both regionally and environmentally appropriate, offer great potential for the bioeconomy overall. An example of this is the cultivation of pennycress in the Upper Midwest, a multi-functional oilseed crop that is cold-tolerant and requires minimal inputs, which could be grown using double or relay cropping to protect soil and water resources over winter; currently, the dominant corn-soybean crop rotations of this region do not include any soil or water protection outside of their summer annual growing cycle (Jordan et al. 2016).

In general, biologically diversified farms managed using insights from agroecology can remain productive and resilient while also conserving water and energy resources, and enhancing other ecosystem services. For example, the strategic incorporation of perennials (including perennial food, energy, or non-crop plants) into small areas of fields has been found to significantly reduce water pollution and create other positive environmental outcomes (Liebman and Schulte, 2015; Liebman et al., 2013; Helmers et al., 2012) while still allowing the most productive areas of fields to be used for more intensive, lower diversity production (“precision conservation”; Berry et al., 2003; Brandes et al., 2016). Systems managed in this way may become even more pivotal as climate change stresses water systems, as demonstrated by the recent persistent drought in California (Morris and Bucini, 2016). Further, in an example focused on pest management, the proximity of more diverse vegetation (including forest and hedge rows) was shown to increase the population of natural enemies as compared to pests in intensive vegetable production (Letourneau et al., 2015). And, according to a global meta-analysis, enhancing diversity by incorporating multiple crops in rotation significantly increased total soil carbon and nitrogen as well as microbial carbon and nitrogen (McDaniel et al. 2014).

Importantly, in addition to the many environmental benefits, research indicates that biological diversity and ecological practices can also have a positive effect on yields. In other studies, diverse crop rotations have further been found to limit yield variability in years with abnormal weather (Gaudin et al., 2015), and increase average yields (Smith et al. 2008; Ponisio et al. 2015), while reducing reliance on purchased inputs. Incorporating conservation agriculture practices more generally (no tillage, crop residue management, crop rotation) has also increased crop yields in several dry environments (Pittelkow et al., 2015).

The accumulating evidence indicates that practices rooted in agroecology and biological diversity could reduce risks related to food security, energy and water resources, climate change and associated weather extremes, and other challenges, especially in the long-term. Whether such practices would ultimately reduce risk and/or bring rewards to farmers, however, depends on incentives, policy systems, and farmer risk-taking behaviors.

Obstacles for agroecology as a leading edge for sustainable solutions

Despite the promise of ecological design in agricultural systems, several hurdles may be preventing its wider acceptance as a framework to address food, energy and water system issues, particularly in the United States. For one thing, in our technology-focused era the fact that agroecology does not emphasize industrial technologies may cause it to be undervalued by producers and consumer alike, even though agroecological solutions often result from sophisticated syntheses of social, economic and environmental components that address underlying problems as parsimoniously as possible (Altieri, 1989; Montenegro de Wit and Iles 2016). But, importantly, there are also numerous infrastructural challenges, development, and adoption that are hindering broader adoption rates that could help foster an appreciation for the elegant multiple-optimization solutions available in agroecology.

In research communities, there has long been recognition that public infrastructure for the science and development of agroecology has been woefully underfunded (Carlisle and Miles, 2013; Lipson, 1997). Recently, an analysis of competitive funding from the U.S. Department of Agriculture confirmed a dearth of funding for projects that incorporated key agroecological practices (e.g., crop rotations, agroforestry, integrated crop-livestock systems), particularly in combination with socioeconomic elements that could realistically help agroecology gain traction at a larger scale (DeLonge et al., 2015). In addition to shortages of research funding in critical areas, training at educational institutions for the next generation of agricultural researchers is often lacking the social sciences (behavioral science, sociology, economic, etc.) that can encourage “systems thinking” and facilitate landscape level change, both of which are essential to agroecology. In cases where systems approaches are actually included in curricula, it is often noted that the programs could be further improved to overcome institutional and cultural barriers hindering student success (Graybill et al., 2006; Romolini et al., 2013; Basche et al., 2014). Finally, although there is a growing number of degree programs in agroecology and food systems in the U.S. (United States Department of Agriculture, 2015), such programs are still the minority relative to agronomy, crop and soil science programs; the lack of existing scholar communities in this area is also likely a factor dampening the pace of transition.

Outside of academic institutions, agricultural producers must overcome significant social, political and economic obstacles in order to diversify their farming or ranching operations. Even for basic environmental best management practices (such as reduced tillage and nutrient management), which often represent non-systemic change, important determinants of farmer adoption have included both financial capacity and connections to knowledge sharing networks (Prokopy et al. 2008; Baumgart-Getz et al. 2012). The literature on cover crops, another basic best management practice, suggests that early adopters require significant trial and error and that it is the operations with a track record of higher levels of crop and livestock diversity that are more likely to adopt the practice (Dunn et al. 2016; Arbuckle and Roesch-McNally 2015; Singer et al. 2007). Further, surveys and interviews with Nebraska farmers and ranchers indicated that many hoped to adopt more sustainable practices to reduce drought risks but were limited by the need to maximize production to maintain cash flow (Knutson et al. 2011). Given the documented real and perceived challenges for farmers who are considering making relatively small changes to management practices, it would be reasonable to expect an even slower uptake of more holistic ecologically-based farming practices, especially without strong support and incentives.

Encouraging the broader adoption of agroecology would undoubtedly require developing more support for farmers wishing to transition their practices and for consumers who would prefer to purchase products from ecologically managed farms. This required support could include policy interventions such as increased support for peer-to-peer farmer networks for information transfer and market support, or supply chains that value the multifunctional benefits achieved by agroecology (Union of Concerned Scientists 2016b; Blesh and Wolf 2014).

Limits of yield-based solutions in the food system, and implications for water and energy

Despite the obstacles, there is a need for new models of agriculture that can remain productive and profitable in the face of rapidly depleting and increasingly stressed fresh water and energy resources. The need to transform food systems specifically is clear when considering that existing food systems are already falling short of addressing current needs related to food security, food access, and nutrition, even before projected population increases. These shortcomings indicate that scaling up current production systems is likely to pose additional problems for energy and water, without necessarily solving problems in the food system.

The right to food, which underlies the need for a productive agricultural system, has been defined as “physical and economic access at all times to sufficient, adequate and culturally acceptable food that is produced and consumed sustainably, preserving access to food for future generations” (United Nations, 2014). In spite of the popular claims that the extant system “feeds the world”, the right to food is not a reality for many people today – even for those in areas with high agronomic productivity. Therefore, although maintaining affordable food prices and sufficient productivity is essential, a sole focus of maximizing output (e.g., crop yield) will not achieve the goal of creating a food system that maximizes overall well-being and equitable outcomes for all (Haynes-Maslow and Salvador, 2015). For example, today in the United States despite impressive agricultural yields from modern farming systems, food insecurity persists for approximately 14% of the U.S. population (United States Department of Agriculture, 2014). Further, chronic health concerns related to the food system are pervasive and include poor mental and physical health outcomes for children (Cook et al., 2004), higher incidences of cardiovascular risks in adults, including hypertension and hyperlipidemia (Seligman et al., 2010) and racially inequitable incidences of diabetes, where there are higher rates in communities of color (Union of Concerned Scientists, 2016c).

Even if there are linkages between food availability, accessibility and health outcomes, is there reason to believe that a shift in agricultural policy would help? Interestingly, existing research evaluating the degree to which current policies actually influence health is mixed. One recent study demonstrated a strong tie between subsidized foods and health outcomes in the U.S., finding that 56% of calories consumed by participants came from major subsidized food commodities and that people who consumed more foods processed with these commodities (such as corn and soy) had significantly higher incidences of cardiometabolic risks (Siegel et al. 2016). However, some economists and public health experts refute the notion that subsidizing commodity crops actually contributes to the “obesity epidemic” and poor health outcomes (Alston et al. 2008, Hawkes et al. 2012). More research is needed to better understand not only the current impacts of policies on health, but the potential positive role of innovative policies.

Efforts to develop and implement new food and agricultural policies that systematically address challenges are likely constrained by existing metrics of agricultural productivity, which have failed to capture critical environmental and societal impacts and often lead to an incomplete understanding of production costs and related tradeoffs (Davis et al. 2012). Specifically, analyses that more comprehensively evaluate the impacts of agricultural production on energy, water, land, health, or other resources are generally lacking, but those that do exist reveal the importance of such research. For example, Cassidy et al. (2013) proposed expanding the definition of yield from crop production per hectare of land to people actually fed, and found that growing food for direct human consumption versus biofuel or animal feed could increase food availability by 70%, enough to accommodate projected population growth. Similarly, Peters et al. (2016) evaluated the relationship between diets and land use by calculating the ability of existing U.S. agricultural land to meet the food needs of the U.S. population under several diet scenarios: current consumption patterns, diets with recommended fruit and vegetable consumption and varied meat intake, and vegetarian and vegan diets. They found that several scenarios could satisfy the caloric needs of all Americans within the current land base (all of which require some reduction of meat consumption), but also highlighted that meeting dietary needs without clearing land may require using more existing farm land to grow grains, fruits, vegetables and pulse crops for direct human consumption (Peters et al., 2016). While these research efforts focused in food systems are good examples of the work needed to expand our understanding of productivity, the mostly commonly used metrics have not yet appropriately included how nutritious, accessible, or affordable food is, nor have they adequately considered the implications for other societal resources, including water and energy systems.

Beyond yield: an urgent call for long-term, systems science

While the need to produce abundant food to support a growing population has long been recognized as an agricultural and policy priority, it is becoming clear that this agricultural objective may be too narrow to guide needed research for transformative solutions, even when looking at food systems alone. Further, as we have discussed, the need to improve agricultural systems reaches past food, most notably to energy and water. For example, bioenergy products have the potential to contribute to energy demands. However, if they require additional land and water resources, the development of these products have implications for both food and water systems. In turn, conserving ground water resources, protecting waterways from pollution, and even mitigating the effects of droughts and floods, are all connected to agricultural land use and management. Although they are interwoven, quantifying societal co-benefits or tradeoffs in food, energy and water systems remains a challenge, and new perspectives, methods, and metrics are needed.

Amidst the obstacles, the field of agroecology stands as a strong source for innovations that can support the needs of a growing population while directly confronting the many outcomes beyond yields that must be addressed to achieve long-term sustainability. These outcomes include efficient use and protection of water as well as the sustainable development of energy resources, and also extend to food access and affordability, quality and healthfulness, and waste (Neff et al., 2015). There is no better time to seek creative solutions to systemic challenges. We must progress beyond yield to include the need for healthy food, sustainable food and energy products, conservation of water and energy resources, and a clean, equitable environment for the public good.

Acknowledgments

The authors would like to thank Ricardo Salvador for discussions and comments that improved the quality of the manuscript.

Funding information

We would like to thank the Union of Concerned Scientists for funding that supported the authors while writing this article.

Competing interests

Elementa Editor-in-Chief for this manuscript, Anne Kapuscinski, is the current Board Chair of the Union of Concerned Scientists. She does not supervise Union of Concerned Scientists staff, nor does she receive financial compensation for being the Board Chair. Ricardo Salvador, Director of the Union of Concerned Scientists Food and Environment Program, is guest editor for a different Elementa forum and was not involved in the peer-review process or management of this submission. He does not receive financial compensation for his guest editor role.

Author contributions

Both co-authors contributed equally to research, writing and revision.

1
Alston
 
JM
Sumner
 
DA
Vosti
 
SA
Farm subsidies and obesity in the United States: National evidence and international comparisons
Food Policy
2008
, vol. 
33
 
6
(pg. 
470
-
479
)
2
Altieri
 
M
Agroecology: A new research and development paradigm for world agriculture
Agriculture, Ecosystems and the Environment
1989
, vol. 
27
 
1–4
(pg. 
37
-
46
)
3
Arbuckle
 
JG
Roesch-McNally
 
GE
Cover crop adoption in Iowa: The role of perceived practice characteristics
Journal of Soil and Water Conservation
2015
, vol. 
70
 
6
(pg. 
418
-
429
)
4
Basche
 
AD
Roesch-McNally
 
GE
Pease
 
LA
Eidson
 
CD
, et al. 
Challenges and opportunities in trans disciplinary science: the experience of next generation scientists in an agriculture and climate research collaboration
Journal of Soil and Water Conservation
2014
, vol. 
69
 
6
(pg. 
176A
-
179A
)
5
Baumgart-Getz
 
A
Prokopy
 
LS
Floress
 
K
Why farmers adopt best management practice in the United States: a meta-analysis of the adoption literature
Journal of Environmental Management
2012
, vol. 
96
 
1
(pg. 
17
-
25
)
6
Berry
 
JK
Delgado
 
JA
Khosla
 
R
Pierce
 
FJ
Precision conservation for environmental sustainability
Journal of Soil and Water Conservation
2003
, vol. 
58
 
6
(pg. 
332
-
339
)
7
Blesh
 
J
Wolf
 
SA
Transitions to agroecological farming systems in the Mississippi River Basin: toward an integrated socioecological analysis
Agriculture and Human Values
2014
, vol. 
31
 
4
(pg. 
621
-
635
)
8
Brandes
 
E
McNunn
 
GS
Schulte
 
LA
Bonner
 
IJ
Muth
 
DJ
, et al. 
Subfield profitability analysis reveals an economic case for cropland diversification
Environmental Research Letters
2016
, vol. 
11
 
1
pg. 
014009
 
9
Carlisle
 
L
Miles
 
A
Closing the knowledge gap: how the USDA could tap the potential of biologically diversified farming systems
Journal of Agriculture, Food Systems and Community Development
2013
, vol. 
3
 (pg. 
219
-
225
)
10
Cassidy
 
ES
West
 
PC
Gerber
 
JS
Foley
 
JA
Redefining agricultural yields: from tonnes to people nourished per hectare
Environmental Research Letters
2013
, vol. 
8
 
3
pg. 
034015
 
11
Cook
 
JT
Frank
 
DA
Berkowitz
 
C
Black
 
MM
Casey
 
PH
, et al. 
Food insecurity is associated with adverse health outcomes among human infants and toddlers
The Journal of Nutrition
2004
, vol. 
134
 
6
(pg. 
1432
-
1438
)
12
Davis
 
AS
Hill
 
JD
Chase
 
CA
Johanns
 
AM
Liebman
 
M
Increasing cropping system diversity balances productivity, profitability and environmental health
PLoS One
2012
, vol. 
7
 
10
pg. 
e47149
 
13
DeLonge
 
MS
Miles
 
A
Carlisle
 
L
Investing in the Transition to Sustainable Agriculture
Environmental Science and Policy
2015
, vol. 
55
 
1
(pg. 
266
-
273
)
14
de Wit
 
MM
Iles
 
A
Toward thick legitimacy: Creating a web of legitimacy for agroecology
Elementa: Science of the Anthropocene
2016
, vol. 
4
 
1
pg. 
000115
 
15
Dunn
 
M
Ulrich-Schad
 
JD
Prokopy
 
LS
Myers
 
RL
Watts
 
CR
Scanlon
 
K
Perceptions and use of cover crops among early adopters: Findings from a national survey
Journal of Soil and Water Conservation
2016
, vol. 
71
 
1
(pg. 
29
-
40
)
16
Environmental Protection Agency [internet]
Sources of Greenhouse Gas Emissions
2015
 
17
Francis
 
C
Van Wort
 
J
Johnson
 
B
How to regenerate rural community and ecoservices: Reversing the tragedy of the commons
Agronomy Journal
2014
, vol. 
106
 
1
(pg. 
95
-
99
)
18
Gaudin
 
ACM
Tolhurst
 
TN
Ker
 
AP
Janoicek
 
K
Tortora
 
C
, et al. 
Increasing crop diversity mitigates weather variations and improves yield stability
PloS One
2015
, vol. 
10
 
2
pg. 
e0113261
 
19
Gliessman
 
SR
Agroecology: The Ecology of Food Systems
2014
3rd ed.
Boca Raton, FL
CRC/Taylor & Francis Group
20
Graybill
 
JK
Dooling
 
S
Shandas
 
V
Withey
 
J
Greve
 
A
, et al. 
A rough guide to Interdisciplinarity: Graduate student perspectives
BioScience
2006
, vol. 
56
 
9
(pg. 
757
-
763
)
21
Hawkes
 
C
Friel
 
S
Lobstein
 
T
Lang
 
T
Linking agricultural policies with obesity and noncommunicable diseases: a new perspective for a globalising world
Food Policy
2012
, vol. 
37
 
3
(pg. 
343
-
353
)
22
Haynes-Maslow
 
L
Salvador
 
R
The Food System Should Unite Us, Not Divide Us
Journal of Agriculture, Food Systems and Community Development
2015
, vol. 
5
 
4
(pg. 
105
-
109
)
23
Helmers
 
MJ
Zhou
 
X
Asbjornsen
 
H
Kolka
 
R
Tomer
 
MD
, et al. 
Sediment removal by prairie filter strips in row-cropped ephemeral watersheds
Journal of Environmental Quality
2012
, vol. 
41
 
5
(pg. 
1531
-
1539
)
24
International Panel of Experts on Sustainable Food Systems (IPES-Food)
From uniformity to diversity: a paradigm shift from industrial agriculture to diversified agroecological systems
International Panel of Experts on Sustainable Food systems
2016
www.ipes-food.org
25
Jordan
 
NR
Dorn
 
K
Runck
 
B
Ewing
 
P
Williams
 
A
, et al. 
Sustainable commercialization of new crops for the bioeconomy
Elementa: Science of the Anthropocene
2016
, vol. 
4
 pg. 
000081
 
26
Knutson
 
CL
Haigh
 
T
Hayes
 
MJ
Widhalm
 
M
Nothwehr
 
J
Kleinschmidt
 
M
Graf
 
L
Farmer perceptions of sustainable agriculture practices and drought risk reduction in Nebraska, USA
Renewable Agriculture and Food Systems
2011
, vol. 
26
 
03
(pg. 
255
-
266
)
27
Kremen
 
C
Miles
 
A
Ecosystem services in biologically diversified versus conventional farming systems: benefits, externalities, and trade-offs
Ecology and Society
2012
, vol. 
17
 
4
pg. 
40
 
28
Kremen
 
C
Williams
 
NM
Thorp
 
RW
Crop pollination from native bees at risk from agricultural intensification
Proceedings of the National Academy of Sciences
2002
, vol. 
99
 
26
(pg. 
16812
-
16816
)
29
Lark
 
TJ
Salmon
 
JM
Gibbs
 
HK
Cropland expansion outpaces agricultural and biofuel policies in United States
Environmental Research Letters
2015
, vol. 
10
 
4
pg. 
044033
 
30
Lesk
 
C
Rowhani
 
P
Ramankutty
 
N
Influence of extreme weather disasters on global crop production
Nature
2016
, vol. 
529
 (pg. 
84
-
87
)
31
Letourneau
 
DK
Bothwell
 
ASG
Kula
 
RR
Sharkey
 
MJ
Stireman
 
JO
Habitat eradication and cropland intensification may reduce parasitoid diversity and natural pest control services in annual crop fields
Elementa Science of the Anthropocene
2015
, vol. 
3
 pg. 
000069
 
32
Liebman
 
M
Helmers
 
MH
Schulte
 
LA
Chase
 
CA
Using biodiversity to link agricultural productivity with environmental quality: Results from three field experiments in Iowa
Renewable Agriculture and Food Systems
2013
, vol. 
28
 
2
(pg. 
115
-
128
)
33
Liebman
 
M
Schulte
 
LA
Enhancing agroecosystem performance and resilience through increased diversification of landscapes and cropping systems
Elementa Science of the Anthropocene
2015
, vol. 
3
 pg. 
000041
 
34
Lipson
 
M
Searching for the” O-word”: analyzing the USDA current research information system for pertinence to organic farming
1997
Santa Cruz, CA
Organic Farming Research Foundation
35
McDaniel
 
MD
Tiemann
 
LK
Grandy
 
AS
Does agricultural crop diversity enhance soil microbial biomass and organic matter dynamics? A meta-analysis
Ecological Applications
2014
, vol. 
24
 
3
(pg. 
560
-
570
)
36
Montgomery
 
DR
Soil erosion and agricultural sustainability
Proceedings of the National Academy of Sciences
2007
, vol. 
104
 
33
(pg. 
13268
-
13272
)
37
Morris
 
KS
Bucini
 
G
California’s drought as opportunity: Redesigning U.S. agriculture for a changing climate
Elem Sci Anth
2016
, vol. 
4
 pg. 
000142
 
38
Neff
 
RA
Kanter
 
R
Vandevijvere
 
S
Reducing Food Loss And Waste While Improving The Public’s Health
Health Affairs
2015
, vol. 
34
 
11
(pg. 
1821
-
1829
)
39
Newbold
 
T
Hudson
 
LN
Arnell
 
AP
Contu
 
S
, et al. 
Has land use pushed terrestrial biodiversity beyond the planetary boundary? A global assessment
Science
2016
, vol. 
353
 
6296
(pg. 
288
-
91
)
40
Peters
 
CJ
Picardy
 
J
Darrouzet-Nardi
 
AF
Wilkins
 
JL
Griffin
 
TS
Fick
 
GW
Carrying capacity of US agricultural land: Ten diet scenarios
Elementa: Science of the Anthropocene
2016
, vol. 
4
 
1
pg. 
000116
 
41
Pittelkow
 
CM
Liang
 
X
Linquist
 
BA
van Groenigen
 
KJ
Lee
 
J
, et al. 
Productivity limits and potentials of the principles of conservation agriculture
Nature
2015
, vol. 
517
 
7534
(pg. 
365
-
368
)
42
Ponisio
 
LC
M’Gonigle
 
LK
Mace
 
KC
Palomno
 
J
de Valpine
 
P
, et al. 
Diversification practices reduce organic to conventional yield gap
Proceedings of the Royal Society of London B: Biological Sciences
2015
, vol. 
282
 
1799
pg. 
20141396
 
43
Porter
 
PP
Mitchell
 
RB
Moore
 
KJ
, et al. 
Reducing hypoxia in the Gulf of Mexico: Reimagining a more resilient agricultural landscape in the Mississippi River Watershed
Journal of Soil and Water Conservation
2015
, vol. 
70
 
3
(pg. 
63A
-
65A
)
44
Prokopy
 
LS
Floress
 
K
Klotthor-Weinkauf
 
D
Baumgart-Getz
 
A
Determinants of agricultural best management practice adoption: Evidence from the literature
Journal of Soil and Water Conservation
2008
, vol. 
63
 
5
(pg. 
300
-
311
)
45
Richey
 
AS
Thomas
 
BF
Lo
 
M
Reager
 
JT
Famiglietti
 
JS
Voss
 
K
Swenson
 
S
Rodell
 
M
Quantifying renewable groundwater stress with GRACE
Water Resources Research
2015
, vol. 
51
 
7
(pg. 
5217
-
5238
)
46
Romolini
 
M
Record
 
S
Garvoille
 
R
Marusenko
 
Y
Geiger
 
RS
The next generation of scientists: Examining the experiences of graduate students in network-level social-ecological science
Ecology and Society
2013
, vol. 
18
 
3
pg. 
42
 
47
Scanlon
 
BR
Faunt
 
CC
Longuevergne
 
L
Reedy
 
RC
Alley
 
WM
McGuire
 
VL
McMahon
 
PB
Groundwater depletion and sustainability of irrigation in the US High Plains and Central Valley
Proceedings of National Academies of Science
2012
, vol. 
109
 
24
(pg. 
9320
-
9325
)
48
Schipanski
 
ME
McDonald
 
GK
Rosenzweig
 
S
Chappell
 
MJ
Bennett
 
EM
, et al. 
Realizing Resilient Food Systems
BioScience
2016
 
Advance online
49
Seligman
 
HK
Laraia
 
BA
Kushel
 
MB
Food insecurity is associated with chronic disease among low-income NHANES participants
The Journal of Nutrition
2010
, vol. 
140
 
2
(pg. 
304
-
310
)
50
Sevilla
 
GE
Woodgate
 
G
Agroecology: Foundations in agrarian social thought and sociological theory
Agroecology and Sustainable Food Systems
2013
, vol. 
37
 (pg. 
32
-
44
)
51
Siegel
 
KR
Bullard
 
KM
Imperatore
 
G
Kahn
 
HS
Stein
 
AD
Ali
 
MK
Narayan
 
KM
Association of Higher Consumption of Foods Derived From Subsidized Commodities With Adverse Cardiometabolic Risk Among US Adults
JAMA Internal Medicine
2016
, vol. 
176
 
8
(pg. 
1124
-
32
)
52
Singer
 
JW
Nusser
 
SM
Alf
 
CJ
Are Cover Crops Being Used in the Us Corn Belt?
Journal of Soil and Water Conservation
2007
, vol. 
62
 
5
(pg. 
353
-
58
)
53
Smith
 
DR
King
 
KW
Williams
 
MR
What is causing the harmful algal blooms in Lake Erie?
Journal of Soil and Water Conservation
2015
, vol. 
70
 
2
(pg. 
27A
-
29A
)
54
Smith
 
RG
Gross
 
KL
Robertson
 
GP
Effects of crop diversity on agroecosystem function: crop yield response
Ecosystems
2008
, vol. 
11
 
3
(pg. 
355
-
366
)
55
Tubiello
 
FN
Salvatore
 
M
Ferrara
 
AF
House
 
J
Federici
 
S
, et al. 
The Contribution of Agriculture, Forestry and other Land Use activities to Global Warming, 1990–2012
Global Change Biology
2015
, vol. 
21
 (pg. 
2655
-
2660
)
56
Union of Concerned Scientists
Subsidizing Waste: How Inefficient U.S. Farm Policy Costs Taxpayers, Businesses and Farmers Billions
2016a
 
57
Union of Concerned Scientists
Growing Economies: Connecting Local Farmers and Large-Scale Food Buyers to Create Jobs and Revitalize America’s Heartland
2016b
 
58
Union of Concerned Scientists
The Devastating Consequences of Unequal Food Access: The Role of Race and Income in Diabetes
2016c
 
59
Union of Concerned Scientists [internet]
Scientists call for public investment in agroecological research
2017
 
60
United Nations
Report of the Special Rapporteur on the right to food, Olivier De Schutter. Final report: The transformative potential of the right to food
2014
 
61
United States Department of Agriculture
National Agriculture Library. Sustainable Agriculture Education and Training Directory
2015
October
 
62
United States Department of Agriculture Economic Research Service
The 20th Century Transformation of U.S. Agriculture and Farm Policy
2005
 
63
United States Department of Agriculture Economic Research Service
Environmental Effects of Agricultural Land Use: The Role of Economics and Policy
2006
 
64
United States Department of Agriculture Economic Research Service
Food Security in the United States
2014
 
65
Veenstra
 
JJ
Burras
 
CL
Soil profile transformation after 50 years of agricultural land use
Soil Science Society of America Journal
2015
, vol. 
79
 
4
(pg. 
1154
-
1162
)
66
Wright
 
CK
Wimberly
 
MC
Recent land use change in the Western Corn Belt threatens grasslands and wetlands
Proceedings of the National Academy of Sciences of the United States of America
2013
, vol. 
110
 
10
(pg. 
4134
-
4139
)
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