Corn ranks first among crops in quantity produced globally, owing to its high yield and to its value as a food for humans and domestic animals. While its water-use efficiency is high compared to that of other crops, the production of high corn yields requires a great deal of water; the availability of water largely determines where the crop is grown. As a high-yielding grass species, corn also requires a substantial supply of nutrients (especially nitrogen) from external sources, including manufactured fertilizers and organic materials such as animal or green manures. This, along with the need to manage soils, weeds, insects, and diseases, makes corn production environmentally consequential.
Corn captures large quantities of sunlight energy through photosynthesis, but its production requires large external inputs of energy, coming mostly (in mechanized production) from fossil fuels. So even though the crop’s high yields moderates the environmental cost per unit of grain produced, minimizing the external environmental consequences of large-scale corn production is an important goal in the quest for greater sustainability of production of this important crop.
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Cultivation and Environmental Impact of Corn
Emerson Nafziger
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Environmental Footprints of Modernization Trends in Rice Production Systems of Southeast Asia
Reiner Wassmann
Assessing the environmental footprints of modern agriculture requires a balanced approach that sets the obviously negative effects (e.g., incidents with excessive use of inputs) against benefits stemming from increased resource use efficiencies. In the case of rice production, the regular flooding of fields comprises a distinctive feature, as compared to other crops, which directly or indirectly affects diverse impacts on the environment. In the regional context of Southeast Asia, rice production is characterized by dynamic changes in terms of crop management practices, so that environmental footprints can only be assessed from time-dependent developments rather than from a static view. The key for the Green Revolution in rice was the introduction of high-yielding varieties in combination with a sufficient water and nutrient supply as well as pest management. More recently, mechanization has evolved as a major trend in modern rice production. Mechanization has diverse environmental impacts and may also be instrumental in tackling the most drastic pollution source from rice production, namely, open field burning of straw. As modernization of rice production is imperative for future food supplies, there is scope for developing sustainable and high-yielding rice production systems by capitalizing on the positive aspects of modernization from a local to a global scale.
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Economics, Agriculture, and Famines
Noel Russell
There are continuing developments in the analysis of hunger and famines, and the results of theoretical and empirical studies of hunger and food insecurity highlight cases where hunger intensifies sufficiently to be identified as famine. The varying ability of those affected to cope with the shocks and stresses imposed on them are central to the development of food insecurity and the emergence of famine conditions and to explaining the complex interrelationships between agriculture, famine, and economics.
There are a number of approaches to understanding how famines develop. The Malthusian approach, which sees population growth as the primary source of hunger and famine, can be contrasted with the free market or Smithian approach, which regards freely operating markets as an essential prerequisite for ensuring that famine can be overcome. A major debate has centered on whether famines primarily emerge from a decline in the availability of food or are a result of failure by households to access sufficient food for consumption, seeking to distinguish between famine as a problem related to food production and availability and famine as a problem of declining income and food consumption among certain groups in the population. These declines arise from the interaction between food markets, labor markets and markets for livestock and other productive farm resources when poor people try to cope with reduced food consumption. Further revisions to famine analysis were introduced from the mid-1990s by authors who interpreted the emergence of famines not as a failure in markets and the economic system, but more as a failure in political accountability and humanitarian response.
These approaches have the common characteristic that they seek to narrow the focus of investigation to one or a few key characteristics. Yet most of those involved in famine analysis or famine relief would stress the multi-faceted and broad-based nature of the perceived causes of famine and the mechanisms through which they emerge. In contrast to these approaches, the famine systems approach takes a broader view, exploring insights from systems theory to understand how famines develop and especially how this development might be halted, reversed, or prevented.
Economists have contributed to and informed different perspectives on famine analysis while acknowledging key contributions from moral philosophy as well as from biological and physical sciences and from political and social sciences. Malthus, Smith, and John Stuart Mill contributed substantially to early thinking on famine causation and appropriate famine interventions. Increased emphasis on famine prevention and a focus on food production and productivity led to the unarguable success of the Green Revolution. An important shift in thinking in the 1980s was motivated by Amartya Sen’s work on food entitlements and on markets for food and agricultural resources. On the other hand, the famine systems approach considers famine as a process governed by complex relationships and seeks to integrate contributions from economists and other scientists while promoting a systems approach to famine analysis.
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Food Safety in a Global Economy: Policies and Social Issues
Tomiko Yamaguchi and Shun-Nan Chiang
Food safety has been a critical issue from the beginning of human existence, but more recently the nature of concerns over food safety has changed. Further, in terms of both scale and impact, the modern problems of food safety are very different from the issues that confronted the past. For example, especially since the late 1990s, society has faced food safety crises and scares arising from threats as diverse as bovine spongiform encephalitis (BSE), dioxin contamination, melamine-tainted infant milk formula, and so forth. These phenomena show that an ever-increasing variety of contaminants such as chemical and microbial agents can potentially find their way into the food supply, while novel foods such as GM foods and cultured meat add new challenges when it comes to certifying food safety.
Food safety has become a particularly complex issue in the context of the global economy because the governance of food safety is entangled with several larger trends at the global scale, including (a) trade liberalization in the 1980s; (b) the adoption of a risk analysis framework by global and national food safety administrations; and (c) the spread of food quality management regimes throughout the entire food industry, from food production to processing and retail. Furthermore, there are vast differences between developed and developing countries with respect to both food safety regulations and prominent food safety issues. These facts, combined with the borderless nature of sociotechnical food systems, contribute to a situation in which it is extremely challenging for any individual country to manage food safety issues within its jurisdiction. This observation underscores the importance of global food safety governance, a goal which is in itself difficult to achieve.
Two especially significant dilemmas have emerged within the existing situation vis-à-vis global food safety governance. The first is the challenges arising from the tensions inherent in a “modern” food safety governance approach, a model that combines a science-based strategy of dealing with food safety problems, on one hand, and the ideal of participatory democracy, on the other hand, in trying to deal with food safety issues. Problems arise from the contradictions between the science-based risked management approach, focused narrowly on monitoring and mitigation of hazards, and the wide-ranging complexity of the social, political, and interpersonal factors that shape people’s real-world concerns about food safety. The second is cross-border application of risk management to food imports in the Global North and its implications for exporting countries in the Global South. Problems arise from disparities in approaches and expectations regarding food safety between the Global North and the South. These two dilemmas have one thing in common: Each inherently contains challenges arising from internal contractions, as when the goal of achieving sound and consistent solutions to food safety issues is pursued alongside the goal of building a broad consensus across varying actors whose values, norms, needs, and interests differ and who are situated in differing socioeconomic and political contexts. Drawing insights from the sociology of agriculture and food and from social studies of science, an attempt is made to unpack the societal and policy challenges of food safety governance in a globalized economy.
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The Forest Transition
Thomas Rudel
Forest transitions take place when trends over time in forest cover shift from deforestation to reforestation. These transitions are of immense interest to researchers because the shift from deforestation to reforestation brings with it a range of environmental benefits. The most important of these would be an increased volume of sequestered carbon, which if large enough would slow climate change. This anticipated atmospheric effect makes the circumstances surrounding forest transitions of immediate interest to policymakers in the climate change era. This encyclopedia entry outlines these circumstances. It begins by describing the socio-ecological foundations of the first forest transitions in western Europe. Then it discusses the evolution of the idea of a forest transition, from its introduction in 1990 to its latest iteration in 2019. This discussion describes the proliferation of different paths through the forest transition. The focus then shifts to a discussion of the primary driver of the 20th-century forest transitions, economic development, in its urbanizing, industrializing, and globalizing forms. The ecological dimension of the forest transition becomes the next focus of the discussion. It describes the worldwide redistribution of forests toward more upland settings. Climate change since 2000, with its more extreme ecological events in the form of storms and droughts, has obscured some ongoing forest transitions. The final segment of this entry focuses on the role of the state in forest transitions. States have become more proactive in managing forest transitions. This tendency became more marked after 2010 as governments have searched for ways to reduce carbon emissions or to offset emissions through more carbon sequestration. The forest transitions by promoting forest expansion would contribute additional carbon offsets to a nation’s carbon budget. For this reason, the era of climate change could also see an expansion in the number of promoted forest transitions.
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Geography and Chronology of the Transition to Agriculture
Peter Bogucki
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.
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Industrial Fertilizers in Agriculture
Gregory L. Willoughby
Agriculture has been said to be the key to civilization development. The longevity of the production of the soils which sustained the population development influenced, in fact caused, the rise and often the collapse of those ancient cultures. Furthermore, the fertilization of those soils, if by new sediment or by other means, enabled some civilizations to survive longer than others. It was only with the development of more consistent fertilization and newer, higher-analysis materials that crop production entered an era where it could reliably feed beyond the family unit but feed the city, and then the whole country. This modern industrial fertilization required fewer people to be devoted to food production so that their efforts could be directed to more secondary and tertiary careers. The growth of the use of fertilizer by over 200% in 40 years has led to an increased scrutiny of its environmental aspect in the early 21st century, and this has led to a revaluation of application procedures and to an increase in research and development of new forms of fertilizer and into ways to change modern fertilizers’ environmental footprints to better steward food production and remedy systems that are off target environmentally. These technologies are sometimes very basic, such as including combinations of elements which help stabilize each other (e.g. sulfur and nitrogen or phosphorus and sulfur). Other technologies include polymer-coating (e.g. slow-release coatings) and impregnatable coatings (e.g. nitrapyrin, NBPT). In other cases, new materials have been developed (e.g. methylated urea) and in yet others progress has come from a mixing of other compounds with the fertilizer (e.g. gypsum to phosphorus fertilizer, or humic acids to nitrogen formulations). Lastly, there has been a rise in the importance of micronutrients as production has increased (e.g. zinc, manganese, and boron) especially as yield levels have increased.
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The Qanat System of Iran and the Maghreb
Ahmad Abbasnejad and Behnam Abbasnejad
A qanat is a kind of subterranean horizontal tunnel and usually excavated in soft sediments. It conducts groundwater to the surface at its emerging point. In addition to the tunnel, each qanat contains anywhere from several to hundreds of vertical wells for removal of dig materials and ventilation of the tunnel. These wells get increasingly deep until the deepest and last one, which is known as the mother well. According to the literature, qanat was first developed around 800 to 1000 bc in northwest of Iran and afterward was utilized in many other countries in Asia, Africa, southern Europe, and even (through independent invention) in the Americas. The areas utilizing the qanat have three characteristics in common: the shortage of surficial water (streams) indicating an arid or semiarid climate; suitable topographical slopes that help conduct groundwater to the surface for a distance by a gently sloping tunnel (qanat); and the presence of unconsolidated sediments (usually alluvial) that both act as subsurface reservoirs and as material that can be easily excavated using primitive tools. In another words, dry areas with mountain-plain topography, alluvial fans, and stream beds (wadis) are suitable for digging qanats. Major parts of Iran and some parts of the Maghreb have such conditions. This is why these two regions have been somewhat dependent on qanats for their water supply. Although the invention of qanats helped human settlement and welfare in drier countries, it had some negative impacts. The presence of humans due to qanats directly impacted the wildlife and vegetation cover of those areas. And in some cases, changes in the groundwater regime caused wilting and drying because of limited water resources for plants and wildlife.
The history of qanat development may be viewed as undergoing three major stages in the dry zones of Iran and the Maghreb, as well as in many other countries where they are present. During the first stage, from 1,000 to 2,000 years after their introduction (depending upon the region) qanats rapidly proliferated as technology spread to new areas. During the second stage, new qanat construction halted, as they had been developed in almost all suitable areas. In the third stage, beginning in some places in the early 20th century, such factors as increasing demand for groundwater, technical developments in water well drilling, and problems with qanat maintenance and urban sprawl caused many qanats to dry out; their numbers in operation have dropped. This decline will continue with varying rates in different countries. Unfortunately, the rate of decline in Iran, the home country of qanats, is more than many other places. This is mainly due to mismanagement.
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Agroecology: Principles and Practices for Diverse, Resilient, and Productive Farming Systems
Miguel A. Altieri
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.
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Environmental Impacts and Benefits of Agroforestry
Shibu Jose
Agroforestry systems, the planting of perennial trees and/or shrubs with annual agronomic crops or pasture, have been proposed as more environmentally benign, alternative systems for agricultural production in both temperate and tropical regions of the world. Agroforestry provides a number of environmental benefits as confirmed by scientific literature. The four major environmental benefits of agroforestry are (1) climate change mitigation through carbon sequestration, (2) biodiversity conservation, (3) soil health enrichment, and (4) air and water quality improvement. In addition to environmental benefits, the economic benefits of multiple crops within agroforestry systems have also generated interest in their adoption by farmers the world over. The major negative impacts come from conversion or degradation of forests following certain traditional practices, which may not fit in the definition of modern agroforestry. Challenges remain for widespread adoption of agroforestry, particularly in the temperate world; however, a new resurgence of interest in this land-use practice among small-scale farmers has shed light on a path toward its possible success. Past evidence clearly indicates that agroforestry, as part of a multifunctional working landscape, can offer not only economic return, but also a number of ecosystem services and environmental benefits for a sustainable society.
