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Toward Sustainable Agricultural Systems in the 21st Century Summary Agriculture is facing daunting challenges. Not only are farmers expected to produce adequate agricultural products at affordable prices to meet the food, fiber, feed, and biofuel needs of a rising global population, but also they are expected to do so under conditions of rising production costs and increasingly scarce natural resources and climate change. Growing awareness of unintended impacts associated with some agricultural production practices has led to heightened societal expectations for improved environmental, community, labor, and animal welfare standards in agriculture. The question arose as to whether U.S. agriculture can meet those challenges and expectations in a sustainable way. The National Research Council (NRC) convened the Committee on Twenty-First Century Systems Agriculture to assess scientific evidence for the strengths and weaknesses of different production, marketing, and policy approaches to improving the sustainability of American agriculture (Box S-1). The committee was asked to discuss how the lessons learned in U.S. agriculture could be relevant to agriculture in different regional and national settings, specifically sub-Saharan Africa. This report provides an update to the 1989 report Alternative Agriculture1 on knowledge gained about the productivity and economics of different practices and systems at increasing levels of complexities (from the level of individual components in a farm, to a whole farm, to a regional level) and their impacts on community and social well-being. It includes case studies on several farms featured in the previous report and an additional set of case studies on farms selected by this committee. This report emphasizes the properties of complex agricultural systems and the interactions, synergies, and tradeoffs that affect the performance and robustness of agricultural practices and farming systems. Targeted public policy can encourage the development and implementation of farming systems designed to improve sustainability. 1 NRC (National Research Council). 1989. Alternative Agriculture. Washington, D.C.: National Academy Press.
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Toward Sustainable Agricultural Systems in the 21st Century BOX S-1 Statement of Task The National Research Council Committee on Twenty-First Century Systems Agriculture was tasked to: Provide an overview of the current state of U.S. agriculture in the domestic and world economies, and describe major challenges to farmers and problems in agricultural production related to the environmental, social, and economic sustainability of agriculture. Review the state of knowledge on farming practices and management systems that can increase the environmental, social, and economic sustainability of agriculture. Identify factors that influence the adoption of farming practices and systems that contribute to the goals of increasing agricultural sustainability. Provide an update to the 1989 report’s methodology to compare the productivity and economics of different systems and practices at levels of increasing complexity (from the level of individual components in a farm, to a whole farm, to a regional level). Describe and analyze several case studies (including some from the 1989 report) that illustrate farming practices and management systems that pursue greater agricultural sustainability. Include general information about the operation, features of the management systems being used, and indicators of productivity, environmental, and financial performance. For case studies from the 1989 report, include a retrospective review of the past performance and the evolution of decision making by those producers over time. Recommend research and development needs for advancing a systems approach to farming in the United States, and suggest ways to strengthen federal policies and programs related to improving agricultural production. Evaluate the transferability of principles underlying farming systems and practices that could improve sustainability of different agricultural settings, and develop supportable conclusions and recommendations to improve the sustainability of agriculture under different natural, economic, and policy conditions in different regional or national settings. This study is supported by the Bill & Melinda Gates Foundation and the W.K. Kellogg Foundation. DEFINING AGRICULTURAL SUSTAINABILITY Sustainability has been described as the ability to meet core societal needs in a way that can be maintained indefinitely without significant negative effects. Accordingly, development of a sustainable agricultural production system requires defining the core societal needs from agriculture, a process that will require a collective vision of what the future characteristics of agriculture should be. Such vision is heavily contested and unresolved in the United States at present. Although developing a widely accepted vision is outside the scope of this study, the committee identified four generally agreed-upon goals (each of which has a set of specific objectives; see Chapter 1) that help define sustainable agriculture: Satisfy human food, feed, and fiber needs, and contribute to biofuel needs. Enhance environmental quality and the resource base. Sustain the economic viability of agriculture. Enhance the quality of life for farmers, farm workers, and society as a whole. Sustainability is best evaluated not as a particular end state, but rather as a process that moves farming systems along a trajectory toward greater sustainability on each of
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Toward Sustainable Agricultural Systems in the 21st Century the four goals. As such, agricultural sustainability is a complex, dynamic, and political concept that is inherently subjective in that different groups in society place different emphasis on each of the four goals. Progress toward the four goals will require robust systems that adapt, evolve, and continue to function in the face of stresses and fluctuating conditions, are productive, use resources efficiently, and balance the four goals within enterprises or farms across and at all scales. The pursuit of sustainability is not a matter of defining sustainable or unsustainable agriculture, but rather is about assessing whether choices of farming practices and systems would lead to a more or less sustainable system as measured by the four goals. Improving sustainability will require identification of key metrics and indicators that can measure progress toward goals, together with monitoring and collecting data and using adaptive management. The committee concluded that if U.S. agricultural production is to meet the challenge of maintaining long-term adequacy of food, fiber, feed, and biofuels under scarce or declining resources and under challenges posed by climate change, and to minimize negative outcomes, agricultural production will have to substantially accelerate progress towards the four sustainability goals. Such acceleration needs to be undergirded by research and policy evolution that are designed to reduce tradeoffs and enhance synergies between the four goals and to manage risks and uncertainties associated with their pursuit. SCIENTIFIC FOUNDATION FOR IMPROVING SUSTAINABILITY Science—including biophysical and social sciences—is essential for understanding agricultural sustainability. Science generates the knowledge needed to predict the likely outcomes of different management systems and expands the range of alternatives that can be considered by farmers, policy makers, and consumers. Although all farms have the potential and responsibility to contribute to different aspects of sustainability, the scale, organization, enterprise diversity, and forms of market integration associated with different farms provide unique opportunities or barriers to improving their ability to contribute to the four goals. Therefore, the committee proposes two parallel and overlapping approaches to ensure continuous improvement in the sustainability performance of U.S. agriculture: incremental and transformative. The incremental approach is an expansion and enhancement of many ongoing efforts that would be directed toward improving the sustainability performance of all farms, irrespective of size or farming systems type, through development and implementation of specific sustainability-focused practices, many of which are the focus of ongoing research and with varying levels of adoption. The transformative approach aims for major improvement in sustainability performance by approaching 21st century agriculture from a systems perspective that considers a multiplicity of interacting factors. It would involve: Developing collaborative efforts between disciplinary experts and civil society to construct a collective and integrated vision for a future of U.S. agriculture that balances and enhances the four sustainability goals. Encouraging and accelerating the development of new markets and legal frameworks that embody and pursue the collective vision of the sustainable future of U.S. agriculture. Pursuing research and extension that integrate multiple disciplines relevant to all four goals of agricultural sustainability.
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Toward Sustainable Agricultural Systems in the 21st Century Identifying and researching the potential of new forms of production systems that represent a dramatic departure from (rather than incremental improvement of) the dominant systems of present-day American agriculture. Identifying and researching system characteristics that increase resilience and adaptability in the face of changing conditions. Adjusting the mix of farming system types and the practices used in them at the landscape level to address major regional problems such as water overdraft and environmental contamination. INCREMENTAL APPROACHES TO IMPROVING SUSTAINABILITY OF U.S. AGRICULTURE The proposed expanded incremental approach would include focused disciplinary research on production; environmental, economic, and social topics; and policies (such as expanded agricultural conservation and environmental programs) to improve the sustainability performance of mainstream agriculture. For example, large livestock farms in the United States produce the majority of the nation’s meat and dairy products. Similarly, BOX S-2 Examples of Practices That Contribute to Sustainability Production Practices Conservation (or reduced) tillage systems have contributed to reducing water-caused soil erosion and surface runoff of nutrients, chemicals, and crop residues. Increased understanding of how conservation or reduced tillage can work with different crops and soil types to reduce energy use and labor has led to increased adoption of those practices. Cover cropping provides ground cover to protect soil and provide other services, including maintaining soil organic matter, providing nutrients to subsequent crops (green manures), trapping excess nutrients in the soil profile following harvest of the primary crop, and preventing leaching losses (catch crops). However, cover crops are not widely planted because of technical, economic, and environmental limitations. Crop diversity, including rotations, intercropping, and using different genetic varieties can contribute to improving soil quality and managing pests and diseases and is particularly important in the management of organic cropping systems. Although incorporation of diversity in cropping systems has increased in some regions, it fluctuates widely with commodity prices. Traditional plant breeding and modern genetic engineering (GE) techniques have resulted in crop varieties with increased yields, pest and disease resistance, enhanced water-use and nutrient-use efficiencies, and other important traits. GE has the potential to contribute a number of solutions for problems, but new varieties need to be tested rigorously and monitored carefully by objective third parties to ensure environmental, economic, and social acceptability and sustainability before they are released for planting. Many technologies for efficient water use such as metering, improved distribution of high-pressure water, and low-pressure, directed-use systems offer promise to address water scarcity. Water reuse is another strategy for addressing water scarcity, but the biological and chemical quality of the reclaimed water requires careful monitoring. Best management practices (BMPs), including nutrient management planning, surface and subsurface drainage management, field buffer strips, riparian area management, and livestock manure management, have been developed to mitigate the runoff of agricultural nutrients and chemicals into the nation’s surface and ground waters. Effectiveness of BMPs at the watershed scale depends, in part, on the coordinated actions of all farms in a watershed. Soil and plant tissue tests, nutrient management plans, and precision agriculture technologies help farmers to increase their farms’ productivity, input-use efficiency, and economic returns by reducing unnecessary use of agricultural fertilizers, pesticides, or water. Experimental and field studies suggest that impacts and economic benefits of those practices and tools can be variable across time and space.
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Toward Sustainable Agricultural Systems in the 21st Century a large portion of corn and soybean are produced on highly mechanized grain farms that specialize in producing a small number of crops and rely heavily on purchased farm inputs to provide crop nutrients and to manage pest, disease, and weed problems. Most, if not all, farms have adopted some practices for improving sustainability. Some farms, including large farms illustrated in the report’s case studies, are highly integrated, but such methods have not been adapted to all environments, and none of the practices has reached its full potential for adoption. Each of those production systems has fostered high productivity and low costs, but many have led to some serious negative social and environmental outcomes (or externalized production costs) that could hinder agriculture’s progress toward improved sustainability. The negative outcomes have led to policy changes and publicly funded research programs explicitly designed to address those concerns. Efforts to improve sustainability of mainstream production system might be incremental in nature, but could have significant benefits given the dominance of those production systems in U.S. agriculture. Since the publication of the report Alternative Agriculture, research has increased understanding of how different farming practices maintain or increase productivity while enhancing natural resources and addressing environmental concerns. Box S-2 lists examples Use of manure, compost, and green manure, as often used in organic systems, can reduce the need for synthetic fertilizer and hence reduce the energy used for fertilizer production. Many farms featured as case studies in this report successfully use on-farm inputs to maintain soil fertility and to insulate themselves from fluctuations in costs of synthetic fertilizer. Published studies, however, show variable results as to whether systems using commercial fertilizers or systems using cover crop-based or animal manure-based nutrient management have higher profits. Those studies often do not include environmental costs and benefits. Integrated pest management (IPM) research has identified promising options for improving soil suppressiveness and inducing crop resistance to some diseases and pests, in addition to classical biological and ecological pest management. The need to study weeds, diseases, pests, and crops as an interacting complex has been recognized. Adoption of IPM has been reasonable for some crops, but overall IPM use is lagging despite its potential for reducing chemical use. Genetic improvement of livestock can contribute to improving sustainability by increasing feed use efficiency and by selecting traits to improve animal health and welfare. Improvements in feed conversion through genetics, nutrition, and management have reduced manure and nutrient excretion per unit animal product produced and reduced land required for production. Business and Marketing Strategies Diversification of farm enterprises can provide multiple income streams for farm operations. Producing a range of crops and animal products can enhance the stability and resilience of farm businesses and can decrease the volatility of farm income. However, studies that analyze the financial impacts of enterprise diversification under real-world conditions are sparse. An increasing number of farmers are raising their farm-level income by increasing the value of their products through sales to niche markets (such as organic or health-food markets) or by selling their products directly to consumers (direct sales) to obtain a larger proportion of the consumers’ dollar spent on the product and to gain control over the prices they get for their products. Practices for Improving Community Well-Being Diverse farm systems, diversified landscapes that include non-crop vegetation, and farming practices that improve water quality can contribute to community and social well-being. Some direct marketing strategies, such as direct sales at farmers’ markets, community-supported agriculture, farm-to-school programs, and agritourism connect farmers to the community and can contribute to community economic security, but those sales strategies lack underpinning research and extension.
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Toward Sustainable Agricultural Systems in the 21st Century of farming practices that can contribute to sustainability goals. Performance and adoption of many of those practices could be further improved by additional biophysical, social, and economic research. Research on the economic and social dimensions of agricultural sustainability complementary to the research on productivity and environmental sustainability is scarce despite its importance in providing farmers with knowledge to design systems that balance different sustainability goals and improve overall sustainability. Studies on economic and social sustainability are complicated by the fact that economic viability is influenced by market and policy conditions and that social acceptability of farms is influenced by the behavior of key actors (including farmers and consumers) and the values of community members. The lack of information on the economic viability of practices and approaches for improving environmental and social sustainability and on how markets and policies influence the economics of those practices could be a barrier to their wide adoption. Nonetheless, the case studies of 15 operating farms in this report illustrate the feasibility of the farming practices and approaches and how they are combined with business and marketing to result in farming systems that balance the four sustainability goals. Continuous research, extension, and experimentation by researchers and farmers are necessary to provide the toolkit necessary for farmers to adapt their systems to changing environmental, social, market, and policy conditions to ensure long-term sustainability. Examples of high-priority areas of research are listed in Box S-3. Because research to develop practices and approaches for improving environmental sustainability and to qualify or quantify their economic and social impacts does not result in a marketable product for industry, it is generally not attractive for private-sector investment. Therefore, such research would have to rely on public funding and institutions, farmer organizations, and civil society sectors. RECOMMENDATION: The U.S. Department of Agriculture and state agricultural institutions and agencies should continue publicly funded research and development (R&D) of key farming practices for improving sustainability to ensure that R&D keeps pace with the needs and challenges of modern agriculture. They should increase support for research that clarifies the economic and social aspects of the many current and potential technologies and management practices and that addresses issues of resilience and vulnerability in biophysical and socioeconomic terms. TRANSFORMATIVE APPROACH TO IMPROVING SUSTAINABILITY OF U.S. AGRICULTURE The transformative approach to improving agricultural sustainability would dramatically increase integrative research by bringing together multiple disciplines to address key dimensions of sustainability simultaneously beyond the agroecological dimension. It would apply a systems approach to agriculture that could result in production systems and an agricultural landscape that are a significant departure from the dominant systems of present-day agriculture. This approach would facilitate development of production approaches that capitalize on synergies, efficiencies, and resilience characteristics associated with complex ecosystems and their linked social, economic, and biophysical systems. It would emphasize integrating information about productivity, environmental, economic, and social aspects of farming systems to understand their interactions and address issues of resilience and vulnerability to changing climate and economic conditions. Moreover, integration would include expanded attention to the role and development of new markets,
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Toward Sustainable Agricultural Systems in the 21st Century BOX S-3 Examples of High-Priority Research in an Incremental Approach to Improving Sustainability Productivity and Environmental Research Assessment of the effectiveness of cover crops in providing ecosystem services such as biological control of agricultural pests, weed suppression, and nutrient and water retention. Assessment of water reuse systems, surface and subsurface drainage systems, and advanced livestock waste management systems that improve the effectiveness of wetlands, enhance water quality and water conservation, and reduce greenhouse-gas emissions. Comparative study of greenhouse-gas emissions and nutrient balances associated with different field management practices for animal wastes and other organic amendments such as green manures and organic mulches and composts. Research and development of non-chemical alternatives (for example, biological control, biofumigation, induced resistance, and soil suppressiveness) for managing weeds, pests, and diseases as a complex. Research that identifies ecosystem benefits from changing agricultural practices, such as planting buffer strips or hedgerows, reducing tillage, and using best management practices, at multiple scales. Socioeconomic Research Assessment of how production practices might affect food attributes (such as pesticide residue, taste, nutritional quality, and food safety). Assessment and comparison of the costs of different production practices and combinations of practices under different policy and market contexts. Research to document and analyze the economic sustainability of direct marketing—for example, to review financial and labor returns to such marketing strategies as sales at farmers’ markets, community-supported agriculture, and farm-to-school programs. Research to document and analyze labor benefits, practices, and their trends in agriculture and their effects on farm profitability. Policy Research Research to improve understanding of the intended and unintended consequences of federal farm, food, and environmental policies that can affect the use of agricultural practices for improving sustainability. new policies and new approaches to research and development that are likely to sustain a systems-oriented agriculture. Options include development of appropriate price signals or incentives to farmers who seek to improve the sustainability of their farms across all four dimensions of sustainability and policies that are less likely to produce unintended consequences in one area of sustainability while addressing another area. Attention to production system types different from the dominant types, such as integrated crop and livestock systems, non-confinement livestock production systems, or highly diversified cropping systems that reduce reliance on purchased inputs, is desirable because the dominant system types might limit the range of technical or managerial possibilities in the pursuit of greater sustainability. Examples suggested in the report include organic cropping systems, low-confinement livestock systems, management intensive rotational grazing, enhanced local food systems, developing perennial grain systems, regional planning and implementation of farming system changes that reduce water overdraft and environmental loading leading to larger hypoxic zones, and planning for production of new products such as cellulosic biofuels.
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Toward Sustainable Agricultural Systems in the 21st Century Interdisciplinary Systems Research Most agricultural research in the United States is conducted to address specific problems. Although a disciplinary approach to agricultural research is necessary to build a foundation of scientific knowledge about how each component of a farming system works, it often undervalues the importance of interconnections and functional relationships between different components of the farming system. A systems approach is necessary to identify and understand the significance of linkages between farming components and other aspects of the environment and economy so that a robust system that takes advantage of synergies and balances tradeoffs can be designed. With some farming system types, the combination of adverse environmental loading, human health and social welfare issues, impacts on local economies, food safety issues, or animal welfare concerns might give impetus to dramatic departures from mainstream agricultural practices. Organic cropping, integrated livestock and crop systems, management-intensive rotational grazing, and low-confinement hog systems are used as examples of potential departures from mainstream agriculture in this report. Those systems illustrate how complementarities and synergies of resource use and containment at the systems level, if managed well, can generate positive outcomes on ecological and social environments. Organic cropping systems integrate many practices for improving sustainability listed earlier. The approach is driven by a philosophy for using biological processes to achieve high soil quality, control pests, and provide favorable growing environments for productive crops, and by the prohibition of most synthetically produced inputs. The alternative livestock production systems were designed to enhance environmental quality, animal welfare, and social acceptability. However, few systematic research studies assess the ability of confined animal systems and other alternatives to address public concerns of production efficiency, food safety, environmental impacts or risks, animal welfare, and labor conditions. Although the farming types that the committee uses as illustrations of systems approaches represent a small proportion of farms in the United States as of 2010, they serve as valuable demonstrations and provide data on how sustainability could be improved. Ultimately, it will be more effective to structure farms and agricultural systems toward balancing the four sustainability goals at the outset rather than to address unintended consequences through piecemeal “technological fixes.” To pursue systemic changes in farming systems, research and development have to address multiple dimensions of sustainability (productivity, and environmental, economic, and social sustainability) and to explore agroecosystem properties, such as complex cropping rotations, integrated crop and livestock production, and enhanced reliance on ecological processes to manage pests, weeds, and diseases (recognizing their interconnectedness and interactions with the environment), that could make systems robust and resilient over time. Despite the need for research to balance and further enhance the four sustainability goals of agriculture, the majority of public research funding is targeted to improving productivity and reducing production costs. Only one-third of public research spending is devoted to exploring environmental, natural resource, social, and economic aspects of farming practices. The report Alternative Agriculture emphasized the importance of a systems approach to agricultural research 20 years ago, yet the proportion of long-term systems agricultural research remains small. Examples of transformative systems type studies include: Holistic comparison of existing organic, conventional, and innovative farming systems in different environments to assess how each system performs and balances overall system efficiencies and resilience with environmental and social impacts.
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Toward Sustainable Agricultural Systems in the 21st Century Holistic comparison of the ability of confined animal systems and other alternatives to address production efficiency, food safety, environmental impacts or risks, animal welfare, and labor conditions. Policies and legal frameworks that provide appropriate pricing and incentives to encourage the balancing of the four sustainability objectives and enhance system resilience and adaptability under dynamic conditions. RECOMMENDATION: Federal and state agricultural research and development programs should aggressively fund and pursue integrated research and extension on farming systems that focus on interactions among productivity, environmental, economic, and social sustainability outcomes. Research should explore the properties of agroecosystems and the interdependencies between biophysical and socioeconomic aspects of farming systems, and how they could make the systems robust and resilient over time. Application of a systems approach to agriculture is not limited to the farm level. The collective and potentially synergistic effects of agricultural systems at a landscape or community scale have gained recognition. However, the scientific foundation for and data needed to develop a landscape approach for improving sustainability of agriculture is sparse. Research suggests that the distribution of farm types and farming activities across a landscape could be designed to achieve greater productivity, resistance, and resilience and improve the sustainability of local and regional agricultural systems that support personal and community well-being. In addition, effective public policy tools that are politically viable and effective in shaping patterns of the agricultural practices or land use at the landscape level are needed. No single agricultural landscape pattern is likely to work in every location; effective landscape patterns would have to be tailored to local conditions and meet particular community needs. Although a landscape approach to agricultural research could inform the design of agroecosystems to maximize synergies, enhance resilience, and inform what policies would be useful in influencing collective actions, programs to encourage such research do not exist. Examples of transformative landscape-scale research include: Develop systems type mixes, patterns, and technologies for landscape diversity that maintain economic output while reducing overall water use. Develop systems type mixes and technologies to reduce nitrogen, phosphorus, and pesticide losses to downstream fragile water bodies, particularly in source regions responsible for hypoxia. Develop tools for modeling of systems and patterns for multipurpose economic, aesthetic, and environmental impacts to enhance community well-being and assist in planning, local policy, market identification, and farmer decision making. Develop policies and legal frameworks that encourage cooperative watershed landscape and ground water management across field and farm boundaries. Generate landscape design options to increase resilience and adaptability to changing conditions using a combination of the above approaches. RECOMMENDATION: The U.S. Department of Agriculture should partner with the National Science Foundation, the U.S. Environmental Protection Agency, key land-grant universities, and farmer-led sustainable agricultural organizations to develop a long-term research and extension initiative that aims to understand
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Toward Sustainable Agricultural Systems in the 21st Century the aggregate effects of farming at a landscape or watershed scale and to devise, encourage, and support the development of collective institutions that could enhance environmental quality while simultaneously sustaining economic viability and community well-being. Returns on research investments could be increased by incorporating farmer knowledge. Much of the technical and managerial innovation in sustainable agriculture has occurred through on-farm innovation and experimentation. Engaging farmers as partners with scientists in innovation, development, extension, and outreach processes could produce effective and long-lasting technology adaptation and adoption. In addition, farmers’ networks and farmer-to-farmer mentoring programs can help spread knowledge gained from research and help adapt such knowledge to farmers’ local conditions. RECOMMENDATION: The U.S. Department of Agriculture and other federal and state agencies that support agricultural research should encourage researchers to include farmer-participatory research or farmer-managed trials as a component of their research. Those agencies should strengthen initiatives for participatory education and peer-to-peer partnerships that could enhance information exchange and enhance farmers’ adoption of new practices and approaches for improving sustainability of agriculture. Efforts to engage farmers and citizens in research and outreach to improve agricultural sustainability will require institutional support. Cooperative Extension programs at the state and regional levels can play a critical role as facilitators and catalysts for fostering interaction among the various stakeholders and for providing educational programs and access to current information. Key Drivers of Change: Markets and Federal and Local Policies Other than available science, knowledge, and skills, the decisions of farmers to use particular farming practices and their ability to move toward more sustainable farming systems are influenced by many external forces such as markets, public policies, and their own values, resources, and land-tenure arrangements. Those structural constraints are in turn influenced by the efforts of broad social movements and organized interest groups that have different perspectives about how agriculture should be organized and how food should be produced and distributed. Growing interests by consumers in food produced using practices perceived as “environmentally friendly,” or that address a particular social concern (such as animal welfare) have led to development of value-trait markets. Similarly, sustainability initiatives in large food retailers open up new markets for food products that are produced using certain practices or farm system types that improve sustainability. Those emerging markets can motivate farmers to transition to farming systems that balance and meet multiple sustainability goals. The use of marketing tools, such as certification and branding of products produced using particular farming practices and systems that increase sustainability, can enhance the value of those farm products and contribute to environmental, social, and economic sustainability of the farm. The impact of public policies aimed at moving agriculture along the sustainability trajectory has been mixed. Some scholars attribute a decrease in the diversity of cropping systems, increases in the use of external farm inputs, and extensive hydrologic modification
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Toward Sustainable Agricultural Systems in the 21st Century of landscapes in part to commodity support payments because these supports provide a strong incentive for farmers to focus on planting program crops by monocropping and to maximize yields per dollar of cost (that is, to focus on only two of the four sustainability goals). Risk management policies can affect sustainability initiatives because some crop insurance products carry substantial subsidized premium structures that can potentially encourage farmers to grow monocrops, which could increase the vulnerability of highly erodible soils and reduce system resilience. Conservation programs are a mechanism for encouraging adoption of particular farming practices, but they are voluntary programs, often with a small proportion of farms participating. Public programs designed to increase incentives to move toward greater sustainability are increasing, but they remain a small portion of the federal and state agricultural policy portfolio. Although market, policy, and institutional contexts are important drivers of the trajectory of U.S. agriculture, the response of individual farmers to the incentives and disincentives created by market conditions and policy contexts can be diverse. Efforts to promote widespread adoption of different farming practices and systems for improving sustainability will require an understanding of how variability among individual, household, farm, and regional-level characteristics affect farmers’ response to incentives and disincentives. The scientific research to date is inadequate to assess the full impacts of current and proposed policy frameworks. RECOMMENDATION: Because of the critical importance of macro-structural or institutional drivers of farmer behavior, the U.S. Department of Agriculture should increase investment in empirical studies of the ways that current and proposed market structures, policies, and knowledge institutions provide opportunities or barriers to expanding the use of farming practices and systems that improve various sustainability goals so that the department can implement changes in policies and institutions that are identified as effective to meeting those goals. Transformation of the agriculture sector will not occur overnight. It will take long-term research and experimentation by the public and private sectors in partnership with farmers. The two parallel approaches to improving sustainability proposed by the committee would ensure incremental improvement toward sustainability, while long-term systemic changes in agricultural systems are being pursued. RELEVANCE OF LESSONS LEARNED TO SUB-SAHARAN AFRICA When considering the relevance of lessons learned in the United States to sub-Saharan Africa, it is important to recognize key differences between the two regions. African farmers produce a wide variety of crops using diverse farming systems across a range of agroecological zones. Most systems are rain-fed, and many soils are severely depleted of nutrients. External inputs are expensive. High transportation costs and lack of infrastructure often inhibit access to outside resources and markets. Specific management approaches need to be developed in that context. Nonetheless, the concepts of sustainability and many of the broad approaches presented in this report are relevant and concur with conclusions from some recent international reports. The committee concluded that: An interdisciplinary systems approach is essential to address the improvement and sustainability of African agriculture that recognizes the social, economic, and
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Toward Sustainable Agricultural Systems in the 21st Century policy contexts within which farming systems operate. Evolving systems would need to address all four sustainability goals and be adapted to local conditions. Research programs need to actively seek input and collaboration from farmers to ensure research being conducted and technologies tested are relevant to their needs. Women, who play a pivotal role in African agriculture, need to be provided with educational and training opportunities and be involved in the development of research agendas. Technologies are needed to address soil, water, and biotic constraints, but they have to be integrated with local ecological and socioeconomic processes. Use of locally available resources would have to be maximized and combined with judicious use of external inputs when necessary. Promising technologies and approaches include soil organic matter management, reduced tillage, integrated fertility management, water harvesting, drip irrigation, stress-resistant crop varieties, improved animal breeds, integration of crops and livestock, and use of global information systems for landscape and regional analysis and planning. Expanding market access will be essential to increase productivity and enhance livelihoods in rural Africa. Investing in rural infrastructure could improve access to local, regional, and international markets. RECOMMENDATION: Agencies and charitable foundations that support research and development of sustainable agriculture in developing countries should ensure that funded programs emphasize a systems approach that reflects the need for adaptability of management strategies and technologies to dynamic local socioeconomic and biophysical conditions, and supports efforts to increase market access.