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Article

Theodore J. K. Radovich

Organic farming occupies a unique position among the world’s agricultural systems. While not the only available model for sustainable food production, organic farmers and their supporters have been the most vocal advocates for a fully integrated agriculture that recognizes a link between the health of the land, the food it produces, and those that consume it. Advocacy for the biological basis of agriculture and the deliberate restriction or prohibition of many agricultural inputs arose in response to potential and observed negative environmental impacts of new agricultural technologies introduced in the 20th century. A primary focus of organic farming is to enhance soil ecological function by building soil organic matter that in turn enhances the biota that soil health and the health of the agroecosystem depends on. The rapid growth in demand for organic products in the late 20th and early 21st centuries is based on consumer perception that organically grown food is better for the environment and human health. Although there have been some documented trends in chemical quality differences between organic and non-organic products, the meaningful impact of the magnitude of these differences is unclear. There is stronger evidence to suggest that organic systems pose less risk to the environment, particularly with regard to water quality; however, as intensity of management in organic farming increases, the potential risk to the environment is expected to also increase. In the early 21st century there has been much discussion centered on the apparent bifurcation of organic farming into two approaches: “input substitution” and “system redesign.” The former approach is a more recent phenomenon associated with pragmatic considerations of scaling up the size of operations and long distance shipping to take advantage of distant markets. Critics argue that this approach represents a “conventionalization” of organic agriculture that will erode potential benefits of organic farming to the environment, human health, and social welfare. A current challenge of organic farming systems is to reconcile the different views among organic producers regarding issues arising from the rapid growth of organic farming.

Article

After millennia of hunting and gathering, prehistoric human societies around the world made the transition to food production using domesticated plants and animals. Several key areas for the initial domestication of plants and animals can be identified: southwestern Asia, Mesoamerica, China, Neotropical South America, eastern North America, Highland New Guinea, and sub-Saharan Africa. In the Old World, wheat, barley, millet, rice, sheep, goats, cattle, and pigs were the major founding crops, while in the New World, maize, squashes, beans, and many other seed and tuber plants were brought into cultivation. Although each area had its own distinct pathway to agriculture, it typically followed a standard path from resource management by hunter-gatherers, incipient cultivation (and livestock herding in some areas), domestication, to commitment to agriculture. Many theories to explain the transition to agriculture have been proposed. Early single-factor hypotheses have been largely discarded in favor models drawn from human evolutionary biology that emphasize the interplay between humans and the species targeted for domestication. Although within the long span of human history, the transition from hunting and gathering to farming in the last 10,000 years can be considered extraordinarily rapid, usually this process took decades, centuries, or even millennia when considered from the perspective of the human factors involved. From these core areas, agricultural practices dispersed, both through their integration into the plant and animal economies of hunter-gatherer societies and through the spread of farming populations. The transition to agriculture had consequences on a global scale, leading to social complexity and, in many cases, urban societies that would be impossible to imagine without agriculture.

Article

Paolo Socci, Alessandro Errico, Giulio Castelli, Daniele Penna, and Federico Preti

Agricultural terraces are widely spread all over the world and are among the most evident landscape signatures of the human fingerprint, in many cases dating back to several centuries. Agricultural terraces create complex anthropogenic landscapes traditionally built to obtain land for cultivation in steep terrains, typically prone to runoff production and soil erosion, and thus hardly suitable for rain-fed farming practices. In addition to acquiring new land for cultivation, terracing can provide a wide array of ecosystem services, including runoff reduction, water conservation, erosion control, soil conservation and increase of soil quality, carbon sequestration, enhancement of biodiversity, enhancement of soil fertility and land productivity, increase of crop yield and food security, development of aesthetic landscapes and recreational options. Moreover, some terraced areas in the world can be considered as a cultural and historical heritage that increases the asset of the local landscape. Terraced slopes may be prone to failure and degradation issues, such as localized erosion, wall or riser collapse, piping, and landsliding, mainly related to runoff concentration processes. Degradation phenomena, which are exacerbated by progressive land abandonment, reduce the efficiency of benefits provided by terraces. Therefore, understanding the physical processes occurring in terraced slopes is essential to find the most effective maintenance criteria necessary to accurately and adequately preserve agricultural terraces worldwide.

Article

Dominic Moran and Jorie Knook

Climate change is already having a significant impact on agriculture through greater weather variability and the increasing frequency of extreme events. International policy is rightly focused on adapting and transforming agricultural and food production systems to reduce vulnerability. But agriculture also has a role in terms of climate change mitigation. The agricultural sector accounts for approximately a third of global anthropogenic greenhouse gas emissions, including related emissions from land-use change and deforestation. Farmers and land managers have a significant role to play because emissions reduction measures can be taken to increase soil carbon sequestration, manage fertilizer application, and improve ruminant nutrition and waste. There is also potential to improve overall productivity in some systems, thereby reducing emissions per unit of product. The global significance of such actions should not be underestimated. Existing research shows that some of these measures are low cost relative to the costs of reducing emissions in other sectors such as energy or heavy industry. Some measures are apparently cost-negative or win–win, in that they have the potential to reduce emissions and save production costs. However, the mitigation potential is also hindered by the biophysical complexity of agricultural systems and institutional and behavioral barriers limiting the adoption of these measures in developed and developing countries. This includes formal agreement on how agricultural mitigation should be treated in national obligations, commitments or targets, and the nature of policy incentives that can be deployed in different farming systems and along food chains beyond the farm gate. These challenges also overlap growing concern about global food security, which highlights additional stressors, including demographic change, natural resource scarcity, and economic convergence in consumption preferences, particularly for livestock products. The focus on reducing emissions through modified food consumption and reduced waste is a recent agenda that is proving more controversial than dealing with emissions related to production.

Article

Confidence in the projected impacts of climate change on agricultural systems has increased substantially since the first Intergovernmental Panel on Climate Change (IPCC) reports. In Africa, much work has gone into downscaling global climate models to understand regional impacts, but there remains a dearth of local level understanding of impacts and communities’ capacity to adapt. It is well understood that Africa is vulnerable to climate change, not only because of its high exposure to climate change, but also because many African communities lack the capacity to respond or adapt to the impacts of climate change. Warming trends have already become evident across the continent, and it is likely that the continent’s 2000 mean annual temperature change will exceed +2°C by 2100. Added to this warming trend, changes in precipitation patterns are also of concern: Even if rainfall remains constant, due to increasing temperatures, existing water stress will be amplified, putting even more pressure on agricultural systems, especially in semiarid areas. In general, high temperatures and changes in rainfall patterns are likely to reduce cereal crop productivity, and new evidence is emerging that high-value perennial crops will also be negatively impacted by rising temperatures. Pressures from pests, weeds, and diseases are also expected to increase, with detrimental effects on crops and livestock. Much of African agriculture’s vulnerability to climate change lies in the fact that its agricultural systems remain largely rain-fed and underdeveloped, as the majority of Africa’s farmers are small-scale farmers with few financial resources, limited access to infrastructure, and disparate access to information. At the same time, as these systems are highly reliant on their environment, and farmers are dependent on farming for their livelihoods, their diversity, context specificity, and the existence of generations of traditional knowledge offer elements of resilience in the face of climate change. Overall, however, the combination of climatic and nonclimatic drivers and stressors will exacerbate the vulnerability of Africa’s agricultural systems to climate change, but the impacts will not be universally felt. Climate change will impact farmers and their agricultural systems in different ways, and adapting to these impacts will need to be context-specific. Current adaptation efforts on the continent are increasing across the continent, but it is expected that in the long term these will be insufficient in enabling communities to cope with the changes due to longer-term climate change. African famers are increasingly adopting a variety of conservation and agroecological practices such as agroforestry, contouring, terracing, mulching, and no-till. These practices have the twin benefits of lowering carbon emissions while adapting to climate change as well as broadening the sources of livelihoods for poor farmers, but there are constraints to their widespread adoption. These challenges vary from insecure land tenure to difficulties with knowledge-sharing. While African agriculture faces exposure to climate change as well as broader socioeconomic and political challenges, many of its diverse agricultural systems remain resilient. As the continent with the highest population growth rate, rapid urbanization trends, and rising GDP in many countries, Africa’s agricultural systems will need to become adaptive to more than just climate change as the uncertainties of the 21st century unfold.

Article

Nutrient pollution can have a negative impact on the aquatic environment, with loss of biodiversity, toxic algal blooms, and a deficiency in dissolved oxygen in surface waters. Agricultural production is one of the main contributors to these problems; this article provides an overview of and background for the main biogeochemical processes causing agricultural nutrient pollution of surface waters. It discusses the main features of the agricultural impact on nutrient loads to surface waters, focusing on nitrogen and phosphorus, and describes some of the main characteristics of agricultural management, including processes and pathways from soil to surface waters. An overview of mitigation measures to reduce pollution, retention in the landscape, and challenges regarding quantification of nutrient losses are also dealt with. Examples are presented from different spatial scales, from field and catchment to river basin scale.

Article

Lars J. Munkholm, Mansonia Pulido-Moncada, and Peter Bilson Obour

Soil tilth is a dynamic and multifaceted concept that refers to the suitability of a soil for planting and growing crops. A soil with good tilth is “usually loose, friable and well granulated”; a condition that can also be described as the soil’s having a good “self-mulching” ability. On the other hand soils with poor tilth are usually dense (compacted), with hard, blocky, or massive structural characteristics. Poor soil tilth is generally associated with compaction, induced by wheel traffic, animal trampling, and/or to natural soil consolidation (i.e., so-called hard-setting behavior). The soil-tilth concept dates back to the early days of arable farming and has been addressed in soil-science literature since the 1920s. Soil tilth is generally associated with soil’s physical properties and processes rather than the more holistic concepts of soil quality and soil health. Improved soil tilth has been associated with deep and intensive tillage, as those practices were traditionally considered the primary method for creating a suitable soil condition for plant growth. Therefore, for millennia there has been a strong focus both in practice and in research on developing tillage tools that create suitable growing conditions for different crops, soil types, and climatic conditions. Deep and intensive tillage may be appropriate for producing a good, short-term tilth, but may also lead to severe long-term degradation of the soil structure. The failure of methods relying on physical manipulation as means of sustaining good tilth has increased the recognition given to the important role that soil biota have in soil-structure formation and stabilization. Soil biology has only received substantial attention in soil science during the last few decades. One result of this is that this knowledge is now being used to optimize soil management through strategies such as more diverse rotations, cover crops, and crop-residue management, with these being applied either as single management components or more preferably as part of an integrated system (i.e., either conservation agriculture or organic farming).Traditionally, farmers have evaluated soil tilth qualitatively in the field. However, a number of quantitative or semi-quantitative procedures for assessing soil tilth has been developed over the last 80 years. These procedures vary from simply determining soil cloddiness to more detailed evaluations whereby soil’s physical properties (e.g., porosity, strength, and aggregate characteristics) are combined with its consistency and organic-matter measurements in soil-tilth indices. Semi-quantitative visual soil-evaluation methods have also been developed for field evaluation of soil tilth, and are now used in many countries worldwide.

Article

Industrialized livestock production can be characterized by five key attributes: confinement feeding of animals, separation of feed and livestock production, specialization, large size, and close vertical linkages with buyers. Industrialized livestock operations—popularly known as CAFOs, for Concentrated Animal Feeding Operations—have spread rapidly in developed and developing countries; by the early 21st century, they accounted for three quarters of poultry production and over half of global pork production, and held a growing foothold in dairy production. Industrialized systems have created significant improvements in agricultural productivity, leading to greater output of meat and dairy products for given commitments of land, feed, labor, housing, and equipment. They have also been effective at developing, applying, and disseminating research leading to persistent improvements in animal genetics, breeding, feed formulations, and biosecurity. The reduced prices associated with productivity improvements support increased meat and dairy product consumption in low and middle income countries, while reducing the resources used for such consumption in higher income countries. The high-stocking densities associated with confined feeding also exacerbate several social costs associated with livestock production. Animals in high-density environments may be exposed to diseases, subject to attacks from other animals, and unable to engage in natural behaviors, raising concerns about higher levels of fear, pain, stress, and boredom. Such animal welfare concerns have realized greater salience in recent years. By consolidating large numbers of animals in a location, industrial systems also concentrate animal wastes, often in levels that exceed the capacity of local cropland to absorb the nutrients in manure. While the productivity improvements associated with industrial systems reduce the resource demands of agriculture, excessive localized concentrations of manure can lean to environmental damage through contamination of ground and surface water and through volatilization of nitrogen nutrients into airborne pollutants. Finally, animals in industrialized systems are often provided with antibiotics in their feed or water, in order to treat and prevent disease, but also to realize improved feed absorption (“a production purpose”). Bacteria are developing resistance to many important antibiotic drugs; the extensive use of such drugs in human and animal medicine has contributed to the spread of antibiotic resistance, with consequent health risks to humans. The social costs associated with industrialized production have led to a range of regulatory interventions, primarily in North America and Europe, as well as private sector attempts to alter the incentives that producers face through the development of labels and through associated adjustments within supply chains.

Article

Alexander N. Hristov

Agriculture is a significant source of methane, contributing about 12% of the global anthropogenic methane emissions. Major sources of methane from agricultural activities are fermentation in the reticulo-rumen of ruminant animals (i.e., enteric methane), fermentation in animal manure, and rice cultivation. Enteric methane is the largest agricultural source of methane and is mainly controlled by feed dry matter intake and composition of the animal diet (i.e., fiber, starch, lipids). Processes that lead to generation of methane from animal manure are similar to those taking place in the reticulo-rumen. Methane emissions from manure, however, are greatly influenced by factors such as manure management system and ambient temperature. Systems that handle manure as a liquid generate much more methane than systems in which manure is handled as a solid. Low ambient temperatures drastically decrease methane emissions from manure. Once applied to soil, animal manure does not generate significant amounts of methane. Globally, methane emissions from rice cultivation represent about 10% of the total agricultural greenhouse gas emissions. In the rice plant, methane dissolves in the soil water surrounding the roots, diffuses into the cell-wall water of the root cells, and is eventually released through the micropores in the leaves. Various strategies have been explored to mitigate agricultural methane emissions. Animal nutrition, including balancing dietary nutrients and replacement of fiber with starch or lipids; alternative sinks for hydrogen; manipulation of ruminal fermentation; and direct inhibition of methanogenesis have been shown to effectively decrease enteric methane emissions. Manure management solutions include solid-liquid separation, manure covers, flaring of generated methane, acidification and cooling of manure, and decreasing manure storage time before soil application. There are also effective mitigation strategies for rice that can be categorized broadly into selection of rice cultivars, water regime, and fertilization. Alternate wetting and drying and mid-season drainage of rice paddies have been shown to be very effective practices for mitigating methane emissions from rice production.

Article

Agriculture has been the principal influence on the physical structure of the English landscape for many thousands of years. Driven by a wider raft of demographic, social, and economic developments, farming has changed in complex ways over this lengthy period, with differing responses to the productive potential and problems of local environments leading to the emergence of distinct regional landscapes. The character and configuration of these, as much as any contemporary influences, have in turn structured the practice of agriculture at particular points in time. The increasing complexity of the wider economy has also been a key influence on the development of the farmed landscape, especially large-scale industrialization in the late 18th and 19th centuries; and, from the late 19th century, globalization and increasing levels of state intervention. Change in agricultural systems has not continued at a constant rate but has displayed periods of more and less innovation.

Article

Wun Jern Ng, Keke Xiao, Vinay Kumar Tyagi, Chaozhi Pan, and Leong Soon Poh

Agriculture waste can be a significant issue in waste management as its impact can be felt far from its place of origin. Post-harvest crop residues require clearance prior to the next planting and a common practice is burning on the field. The uncontrolled burning results in air pollution and can adversely impact the environment far from the burn site. Agriculture waste can also include animal husbandry waste such as from cattle, swine, and poultry. Animal manure not only causes odors but also pollutes water if discharged untreated. However, agricultural activities, particularly on a large scale, are typically at some distance from urban centers. The environmental impacts associated with production may not be well recognized by the consumers. As the consumption terminal of agricultural produce, urban areas in turn generate food waste, which can contribute significantly to municipal solid wastes. There is a correlation between the quantity of food waste generated and a community’s economic progress. Managing waste carries a cost, which may illustrate cost transfer from waste generators to the public. However, waste need not be seen only as an unwanted material that requires costly treatment before disposal. The waste may instead be perceived as a raw material for resource recovery. For example, the material may have substantial quantities of organic carbon, which can be recovered for energy generation. This offers opportunity for producing and using renewable and environment-friendly fuels. The “waste” may also include quantities of recoverable nutrients such as nitrogen and phosphorus.

Article

Early agricultural and arboricultural practices in the Pacific are based on vegetative principles, namely, the asexual propagation and transplantation of plants. A vegetative orientation is reflected in the exploitation of underground storage organs (USOs) within Near Oceania, as well as Island Southeast Asia, during the Pleistocene. During the early Holocene, people in the New Guinea region (including Near Oceania) began to intensify the management of plant resources in different landscapes. The increased degree of plant management, as well as associated environmental transformation, is most clearly manifest in the agricultural chronology at Kuk Swamp in the highlands of Papua New Guinea. At Kuk, shifting cultivation was potentially practiced during the early Holocene, with mounded cultivation by c. 7000–6400 cal BP and ditched drainage of wetlands for cultivation by c. 4400–4000 cal BP. Comparable agricultural records are lacking for other regions of Near Oceania; lowland sites indicate a range of arboricultural practices focused on fruit- and nut-bearing trees during the Terminal Pleistocene and throughout the Holocene, as well as potentially sago during the late Holocene. By c. 4000–3000 cal BP, indigenous agricultural and arboricultural elements were integrated with new cultural traits from Southeast Asia, including domestic animals, pottery and potentially new varieties of traditional crops. From c. 3250 to 2800 cal BP, different elements of agricultural and arboricultural practices from lowland New Guinea and Island Melanesia were taken by Lapita pottery–bearing colonists into the western Pacific. A later period of agricultural expansion occurred around c. 1000–750 cal BP with the colonization of eastern Polynesia. Agricultural practices and crops were variably taken and adapted to different islands and island groups across the Pacific. Additional transformations to agriculture occurred with the Polynesian adoption of the sweet potato (Ipomoea batatas), a South American domesticate, as well as following protohistoric and historic encounters.

Article

The Basin of Mexico is a key world region for understanding agricultural intensification and the development of ancient and historic cities and states. Archaeologists working in the region have had a long-standing interest in understanding the dynamics of interactions between society and environment and their research has been at the forefront of advances in both method and theory. The Basin of Mexico was the geopolitical core of the Aztec empire, the largest state in the history of Mesoamerica. Its growth was sustained by a complex economy that has been the subject of much research. Two themes underlie a broad interest in the pre-Hispanic agriculture of the Basin of Mexico. First, how with a Neolithic technology did the Aztecs and their predecessors sustain the growth of large cites, dense rural populations, and the largest state system in the history of pre-Hispanic Mesoamerica? Second, what is the relationship of agricultural intensification and urbanization and state formation? Mesoamerica is the only world region where primary civilizations developed that lacked domestic herbivores for either food or transportation. Their farming depended entirely on human labor and hand tools but sustained large cities, dense populations, and complex social institutions. Intensive agriculture began early and was promoted by risk, ecological diversity, and social differentiation, and included irrigation, terracing, and drained fields (chinampas). Most farming was managed by smallholder households and local communities, which encouraged corporate forms of governance and collective action. Environmental impacts included erosion and deposition, but were limited compared with the degradation that took place in the colonial period.

Article

Kandace D. Hollenbach and Stephen B. Carmody

The possibility that native peoples in eastern North America had cultivated plants prior to the introduction of maize was first raised in 1924. Scant evidence was available to support this speculation, however, until the “flotation revolution” of the 1960s and 1970s. As archaeologists involved in large-scale projects began implementing flotation, paleoethnobotanists soon had hundreds of samples and thousands of seeds that demonstrated that indigenous peoples grew a suite of crops, including cucurbit squashes and gourds, sunflower, sumpweed, and chenopod, which displayed signs of domestication. The application of accelerator mass spectrometry (AMS) dating to cucurbit rinds and seeds in the 1980s placed the domestication of these four crops in the Late Archaic period 5000–3800 bp. The presence of wild cucurbits during earlier Archaic periods lent weight to the argument that native peoples in eastern North America domesticated these plants independently of early cultivators in Mesoamerica. Analyses of DNA from chenopods and cucurbits in the 2010s definitively demonstrated that these crops developed from local lineages. With evidence in hand that refuted notions of the diffusion of plant domestication from Mesoamerica, models developed in the 1980s for the transition from foraging to farming in the Eastern Woodlands emphasized the coevolutionary relationship between people and these crop plants. As Archaic-period groups began to occupy river valleys more intensively, in part due to changing climatic patterns during the mid-Holocene that created more stable river systems, their activities created disturbed areas in which these weedy plants thrive. With these useful plants available as more productive stands in closer proximity to base camps, people increasingly used the plants, which in turn responded to people’s selection. Critics noted that these models left little room for intentionality or innovation on the part of early farmers. Models derived from human behavioral ecology explore the circumstances in which foragers choose to start using these small-seeded plants in greater quantities. In contrast to the resource-rich valley settings of the coevolutionary models, human behavioral ecology models posit that foragers would only use these plants, which provide relatively few calories per time spent obtaining them, when existing resources could no longer support growing populations. In these scenarios, Late Archaic peoples cultivated these crops as insurance against shortages in nut supplies. Despite their apparent differences, current iterations of both models recognize humans as agents who actively change their environments, with intentional and unintentional results. Both also are concerned with understanding the social and ecological contexts within which people began cultivating and eventually domesticating plants. The “when” and “where” questions of domestication in eastern North America are relatively well established, although researchers continue to fill significant gaps in geographic data. These primarily include regions where large-scale contract archaeology projects have not been conducted. Researchers are also actively debating the “how” and “why” of domestication, but the cultural ramifications of the transition from foraging to farming have yet to be meaningfully incorporated into the archaeological understanding of the region. The significance of these native crops to the economies of Late Archaic and subsequent Early and Middle Woodland peoples is poorly understood and often woefully underestimated by researchers. The socioeconomic roles of these native crops to past peoples, as well as the possibilities for farmers and cooks to incorporate them into their practices in the early 21st century, are exciting areas for new research.

Article

Agriculture is practiced on 38% of the landmass on Earth, and having replaced natural ecosystems, it is the largest terrestrial biome on Earth. Agricultural biomes are typically focused on annual crops that are produced as a succession of genetically uniform monocultures. Compared to the ecosystems they replaced, agroecosystems provide fewer ecosystem functions and contain much less biodiversity. The large-scale conversion from natural lands to agriculture occurred centuries ago in the Old World (Africa, China, Europe, and India), but in many areas during the latter 20th and early 21st centuries, especially tropical areas with rich biodiversity, agriculture is an emerging industry. Here, displacement of natural ecosystems is also a late 20th-century occurrence, and much of it is ongoing. Regardless of where or when agriculture was established, biodiversity declined and ecosystem services were eroded. Agricultural practices are the second largest contributor to biodiversity loss, due to the loss of habitat, competition for resources, and pesticide use. Most (~96%) of the land used to produce crops is farmed using conventional methods, while smaller percentages are under organic production (~2%) or are producing biotech crops (~4%). Regardless of how agriculture is practiced, it exacts a toll on biodiversity and ecosystem services. While organic agriculture embraces many ecological principals in producing food, it fails to recognize the value of biotechnology as a tool to reduce the environmental impact of agriculture. Herbicide- and/or insect-resistant crops are the most widely planted biotech crops worldwide. Biotech crops in general, but especially insect-resistant crops, reduce pesticide use and increase biodiversity. The widespread adoption of glyphosate-resistant crops increased the use of this herbicide, and resistance evolved in weeds. On the other hand, glyphosate has less environmental impacts than other herbicides. Because of the limited scale of biotech production, it will not have large impacts on mitigating the effects of agriculture on biodiversity and ecosystem services. To have any hope of reducing the environmental impact of agriculture, agro-ecology principals and biotechnology will need to be incorporated. Monetizing biodiversity and ecosystem services through incorporation into commodity prices will incentivize producers to be part of the biodiversity solution. A multi-level biodiversity certification is proposed that is a composite score of the biodiversity and ecosystem services of an individual farm and the growing region were the food is produced. Such a system would add value to the products from farms and ranches proportionate to the level by which their farm and region provides biodiversity and ecosystem services as the natural ecosystem it replaced.

Article

Juha Helenius, Alexander Wezel, and Charles A. Francis

Agroecology can be defined as scientific research on ecological sustainability of food systems. In addressing food production and consumption systems in their entirety, the focus of agroecology is on interactions and processes that are relevant for transitioning and maintaining ecological, economic, political, and social-cultural sustainability. As a field of sustainability science, agroecology explores agriculture and food with explicit linkages to two other widespread interpretations of the concept of agroecology: environmentally sound farming practices and social movements for food security and food sovereignty. In the study of agroecology as science, both farming practices and social movements emerge as integrated components of agroecological research and development. In the context of agroecology, the concept of ecology refers not only to the science of ecology as biological research but also to environmental and social sciences with research on social systems as integrated social and ecological systems. In agroecological theory, all these three are merged so that agroecology can broadly be defined as “human food ecology” or “the ecology of food systems.” Since the last decades of the 20th century many developments have led to an increased emphasis on agroecology in universities, nonprofit organizations, movements, government programs, and the United Nations. All of these have raised a growing attention to ecological, environmental, and social dimensions of farming and food, and to the question of how to make the transition to sustainable farming and food systems. One part of the foundation of agroecology was built during the 1960s when ecologically oriented environmental research on agriculture emerged as the era of optimism about component research began to erode. Largely, this took place as a reaction to unexpected and unwanted ecological and social consequences of the Green Revolution, a post–World War II scaling-up, chemicalization, and mechanization of agriculture. Another part of the foundation was a nongovernmental movement among thoughtful farmers wanting to develop sustainable and more ecological/organic ways of production and the demand by consumers for such food products. Finally, a greater societal acceptance, demand for research and education, and public funding for not only environmental ecology but also for wider sustainability in food and agriculture was ignited by an almost sudden high-level political awakening to the need for sustainable development by the end of 1980s. Agroecology as science evolved from early studies on agricultural ecosystems, from research agendas for environmentally sound farming practices, and from concerns about addressing wider sustainability; all these shared several forms of systems thinking. In universities and research institutions, agroecologists most often work in faculties of food and agriculture. They share resources and projects among scientists having disciplinary backgrounds in genetics (breeding of plants and animals), physiology (crop science, animal husbandry, human nutrition), microbiology or entomology (crop protection), chemistry and physics (soil science, agricultural and food chemistry, agricultural and food technology), economics (of agriculture and food systems), marketing, behavioral sciences (consumer studies), and policy research (agricultural and food policy). While agroecologists clearly have a mandate to address ecology of farmland, its biodiversity, and ecosystem services, one of the greatest added values from agroecology in research communities comes from its wider systems approach. Agroecologists complement reductionist research programs where scientists seek more detailed understanding of detail and mechanisms and put these into context by developing a broader appreciation of the whole. Those in agroecology integrate results from disciplinary research and increase relevance and adoption by introducing transdisciplinarity, co-creation of information and practices, together with other actors in the system. Agroecology is the field in sustainability science that is devoted to food system transformation and resilience. Agroecology uses the concept of “agroecosystem” in broad ecological and social terms and uses these at multiple scales, from fields to farms to farming landscapes and regions. Food systems depend on functioning agroecosystems as one of their subsystems, and all the subsystems of a food system interact through positive and negative feedbacks, in their complex biophysical, sociocultural, and economic dimensions. In embracing wholeness and connectivity, proponents of agroecology focus on the uniqueness of each place and food system, as well as solutions appropriate to their resources and constraints.

Article

Worldwide, governments subsidize agriculture at the rate of approximately 1 billion dollars per day. This figure rises to about twice that when export and biofuels production subsidies and state financing for dams and river basin engineering are included. These policies guide land use in numerous ways, including growers’ choices of crop and buyers’ demand for commodities. The three types of state subsidies that shape land use and the environment are land settlement programs, price and income supports, and energy and emissions initiatives. Together these subsidies have created perennial surpluses in global stores of cereal grains, cotton, and dairy, with production increases outstripping population growth. Subsidies to land settlement, to crop prices, and to processing and refining of cereals and fiber, therefore, can be shown to have independent and largely deleterious effect on soil fertility, fresh water supplies, biodiversity, and atmospheric carbon.

Article

The ancient Near East was one of the earliest centers of agriculture in the world, giving rise to domesticated herd animals, cereals, and legumes that today have become primary agricultural staples worldwide. Although much attention has been paid to the origins of agriculture, identifying when, where, and how plants and animals were domesticated, equally important are the social and environmental consequences of agriculture. Shortly after the advent of domestication, agricultural economies quickly replaced hunting and gathering across Mesopotamia, the Levant, and Anatolia. The social and environmental context of this transition has profound implications for understanding the rise of social complexity and incipient urbanism in the Near East. Economic transformation accompanied the expansion of agriculture throughout small-scale societies of the Near East. These farmsteads and villages, as well as mobile pastoral groups, formed the backbone of agricultural production, which enabled tradable surpluses necessary for more expansive, community-scale economic networks. The role of such economies in the development of social complexity remains debated, but they did play an essential role in the rise of urbanism. Cities depended on agricultural specialists, including farmers and herders, to feed urban populations and to enable craft and ritual specializations that became manifest in the first cities of southern Mesopotamia. The environmental implications of these agricultural systems in the Mesopotamian lowlands, especially soil salinization, were equally substantial. The environmental implications of Mesopotamian agriculture are distinct from those accompanying the spread of agriculture to the Levant and Anatolia, where deforestation, erosion, and loss of biodiversity can be identified as the hallmarks of agricultural expansion. Agriculture is intimately connected with the rise of territorial empires across the Near East. Such empires often controlled agricultural production closely, for both economic and strategic ends, but the methods by which they encouraged the production of specific agricultural products and the adoption of particular agricultural strategies, especially irrigation, varied considerably between empires. By combining written records, archaeological data from surveys and excavation, and paleoenvironmental reconstruction, together with the study of plant and animal remains from archaeological sites occupied during multiple imperial periods, it is possible to reconstruct the environmental consequences of imperial agricultural systems across the Near East. Divergent environmental histories across space and time allow us to assess the sustainability of the agricultural policies of each empire and to consider how resulting environmental change contributed to the success or failure of those polities.

Article

Agriculture is at the very center of the human enterprise; its trappings are in evidence all around, yet the agricultural past is an exceptionally distant place from modern America. While the majority of Americans once raised a significant portion of their own food, that ceased to be the case at the beginning of the 20th century. Only a very small portion of the American population today has a personal connection to agriculture. People still must eat, but the process by which food arrives on their plates is less evident than ever. The evolution of that process, with all of its many participants, is the stuff of agricultural history. The task of the agricultural historian is to make that past evident, and usable, for an audience that is divorced from the production of food. People need to know where their food comes from, past and present, and what has gone into the creation of the modern food system.

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Agroecology is a science that applies ecological concepts and principles to the design and management of sustainable agricultural ecosystems. Inspired by the diversified models of traditional agriculture, agroecologists promote crop diversification (polycultures, crop-livestock combinations, rotations, agroforestry systems, etc.) as an effective agroecological strategy for introducing more biodiversity into agroecosystems, which in turn provides a number of ecological services to farmers, such as natural soil fertility, pest regulation, pollination, and others. The agroecological approach involves the application of blended agricultural and ecological sciences with indigenous knowledge systems. A variety of agroecological and participatory approaches have shown in many rural areas very positive outcomes, even under adverse environmental and socioeconomic conditions. Potentials include raising crop yields and total farm output, increasing stability of production through diversification, enhancing resilience of farms to climate change, improving diets and income, and conservation of the natural resource base and biodiversity. Agroecological principles can also be applied to break the monoculture nature of modern mechanized farms. Strategies include complex crop rotations, cover cropping in vineyards and fruit orchards, strip intercropping, and so on. The ultimate goal is to develop integrated diversified and resilient agroecosystems with minimal dependence on external, off-farm inputs.