A 24-hour recall is a dietary assessment tool, commonly used in nutrition research, that consists of a structured interview or standardised questionnaire in which participants are asked to recall all the food and drink they have consumed during the previous 24 hours. In comparison to other common methods such as food frequency questionnaires, 24-hour recalls provide relatively detailed information about participants’ food intakes. Important limitations include the inability to account for day-to-day variations and reliance on participants’ ability to accurately remember the food and drink they have consumed.
Acidification refers to changes to the chemistry of a body of water that make it more acidic over time (i.e. increased hydrogen ion availability). This change in acidity can then affect many other reactions that take place in water, including those important for ecosystem functioning.
Agri-food system refers to the constellation of social, political, economic and environmental processes and actors involved in the production, distribution and consumption of food and related agricultural products. It encompasses all varieties of food production including aquaculture, forest-based production, livestock and crops, and focuses on both their biophysical and socio-economic characteristics.
Agricultural intensification is the process of increasing the inputs of agricultural resources (e.g. seeds, labour, fertilisers, pesticides, technologies, knowledge) to increase the level of yield per unit of farmland or pasture. Agricultural intensification is not always clearly or consistently defined and is often confused with the term intensive agriculture. Unlike intensive agriculture, which could be seen as a specific system of agronomy, agricultural intensification is a general process that can apply, in principle, to any type of agricultural production. Examples of agricultural intensification may range from using new pesticides in intensive agriculture to intensifying the use of indigenous and context-specific knowledge in local farming practices. Although agricultural intensification can take many forms, it always involves the intensification of some types of agricultural input with a view to increase levels of yields.
Agricultural production is the range of practices and approaches that are employed to transform agricultural inputs (e.g. labour, knowledge, land, water, seeds, fertilisers, pesticides) into agricultural outputs (e.g. yields and environmental impacts). Different types of agricultural production include precision farming, agroecology, organic farming, and intensive livestock farming.
Agricultural yield is the average net output of agricultural product (e.g. in kCal, grams protein, or net profit) per unit of farmland per year. The total amount of farmland includes all land that is required to generate the output (e.g. also land that is used to grow feeds or to produce manure).
Agroecology can be defined as a range of agricultural practices that are based on applying ecological concepts and principles to optimize interactions between plants, animals, humans, and the environment. Agroecology also places strong emphasis on the social and ethical aspects of food production. Its advocates tend to have a preference for organic practices (e.g. the avoidance of mineral fertilisers and chemical inputs, and instead prefer the use of biofertilisers, natural pesticides and crop rotation), it also emphasises the need for a ‘multifunctional’ farm system to produce both food and non-food outputs, and for smallholder and indigenous, as opposed to large scale farming. Agroecology has been interpreted in different ways: it also refers to a social movement and field of science.
Alternative food movements generally exist to challenge the current negative consequences of food systems. Fair trade, organic, food justice, food sovereignty, vegan and vegetarian movements can all be seen as offering alternatives to the status quo and as such form part of the "alternative food movement;" it can be said that there are several movements, rather than just one.
Anthropocentrism literally means human-centred. It refers to a philosophy and worldview that bases moral worth on the capacity for analytic thought and judgement, and therefore sees humans as separate from and distinctive to the rest of the natural world. In some cases, this thinking is associated with the perception that nature only has value in the extent to which it can be exploited to meet human needs. It is often suggested that capitalism and western liberal democracy are informed by an anthropocentric worldview, and some people blame anthropocentrism for climate and environmental crises and the depletion of natural resources.
Arable crops are those such as wheat and barley, which require good soil quality and a favourable climate to grow, and land amenable to the use of ploughing and harvesting machinery. Arable land is by definition land used to grow arable crops, in contrast to land used for fruit and vegetable crops and for pasture used to feed grazing animals.
Big food is generally used as a term of criticism, to refer to the most powerful global food industry players. Most commonly it denotes large companies from the food manufacturing, processing and retailing sectors, but can also be used to refer to large agricultural producers as well as companies that provide agricultural inputs such as seeds, fertilisers and pesticides.
Biodiversity refers in the broadest sense to the variety and variability of living organisms in a particular area, or on earth in general. More specifically, the concept is used to denote different aspects of the variety and variability of life, e.g. the number of species in an area (species richness) or the size of species’ populations (species abundance). Biodiversity is measured in different ways and at various scales from the genetic through to the landscape level.
Biodiversity conservation refers to all human activity aimed at the preservation of both the variety and variability of living organisms in a particular area of concern, or on earth in general. People value different aspects of biodiversity in different ways, and can have different priorities in biodiversity conservation e.g. to protect an endemic species or a species that supports an ecological process important to human wellbeing such as pollination.
Biodynamic agriculture is a form of agriculture rooted in the ideas of German philosopher Rudolf Steiner, promoting holistic approaches to farm management, and the use of ecological methods rather than chemical inputs. Its on-farm practices overlap significantly with organic methods. However biodynamic practitioners also emphasise spiritual and mystical elements of human/nature relationships and many use astronomical calendars to guide sowing and harvesting, and fermented herbal remedies to promote plant and soil health and healing.
Biological nitrogen fixation is the process through which atmospheric nitrogen (N2) is converted into ammonia (NH3) or related nitrogenous compounds by bacteria. BNF includes both the fixation of these compounds by bacteria that are present in the soil and by bacteria that live in the root nodules of legumes and certain other plant and tree species. The latter form of BNF is a symbiotic process: the bacteria provide the plant or tree with nitrogen compounds while the plant or tree provides the bacteria with carbohydrates. Nitrogen-fixating plant and tree species are often able to live on relatively poor soils with little need for additional manure or synthetic nitrogen fertiliser. Increased reliance on BNF as opposed to fertilisers is often considered to be an important aspect of a more sustainable food system.
Biotechnology is defined by the United Nations as “any technological application that uses biological systems, living organisms, or derivatives thereof, to make or modify products or processes for specific use”. Applied to agriculture, biotechnology involves controversial as well as uncontroversial practices. Examples of biotechnology are the genetic engineering of crops (GMOs), conventional cross-breeding, breeding based on individual plants’ and animals’ genetic traits (molecular marking), cloning animals, and the production of new vaccines using microbiological methods.
C3 plants are those whose method of photosynthesis is adapted to cooler and wetter climates. They represent the majority of plants globally and include rice, soybean, and wheat. C3 plants are less efficient at creating energy for growth than C4 type plants in hot and dry climates.
C4 plants are those whose method of photosynthesis is adapted to hotter and dryer climates. They represent only a small fraction of plants globally. Examples include some grasses, maize, sugar cane, millet, and sorghum. In hot and dry climates, it is more efficient at creating energy for growth than C3 plants.
Carbon dioxide equivalent (CO2.eq) is a measure used to compare and combine the warming effect of emissions from different greenhouse gases, using single measure of impact. This is done on the basis of a conversion factor known as the Global Warming Potential (GWP), which is the ratio of the total energy trapped by a unit of greenhouse gas (e.g. a tonne of methane) over a specific period of time (normally 100 years), to that trapped by carbon dioxide over the same time period.
A carbon price is a cost that must be paid for the right to produce a unit of carbon pollution. This may take the form of a carbon tax on pollution or an obligation to buy permits from a carbon market. In either case, the goal is to promote investment by polluters to reduce emissions of carbon dioxide and other greenhouse gases.
Carbon sequestration is any process by which carbon dioxide is removed from the atmosphere and stored elsewhere, whether by biological or technological means. There are two main types of carbon sequestration, terrestrial (carbon plants and soils), and geologic (carbon stored in rock formations) . One classic example of carbon sequestration is reforestation.
Choice architecture refers to the design of which choices are made available or not to people in a given context, and how these different choices are presented to them. In any context, there is always a choice architecture affecting decision making, whether deliberately designed or not. For example people's purchasing decisions in a shop are dictated by the products available to buy in a grocery shop, their price, their presentation and visibility, the extent to which they are advertised and promoted and so forth: these collectively constitute the choice architecture.
Climate smart agriculture (CSA) was first introduced by the FAO in 2010 as an integrated approach geared at reorienting and redesigning agricultural systems to address and build resilience to climate change, and is often discussed in the context of low-income countries. CSA involves three interconnected elements: increasing agricultural productivity and incomes; adapting and building resilience to climate change; and the mitigation of greenhouse gas emissions. It aims to identify context specific agricultural strategies supporting these elements and guide coordinated actions among stakeholders (e.g. farmers, researchers, private sector, civil society and policy makers) from the farm to the global level. CSA is criticised for justifying nearly any form of agriculture (thereby ‘greenwashing’ unsustainable practices) and for failing to address enduring inequalities in food production and distribution. CSA is closely related to the concepts of sustainable intensification and ecological intensification but differs from them in its strong focus on planning and implementation for climate change adaptation and mitigation, and less on reducing environmental impacts beyond emissions.
A cohort study, commonly used in medical and nutritional epidemiology, is a longitudinal study that samples a cohort (a group of people that is defined by having experienced the same event, e.g. birth or graduation, in a selected time period) and follows it over time to investigate people’s exposure to certain factors (e.g. the consumption of certain foods) and the occurrence of particular health outcomes. For example, a cohort study may measure the dietary patterns over time of a group of people who were born between 1960 and 1970 to find out which dietary patterns are associated with the development of diabetes or particular cancers. There are two types of cohort studies. Prospective studies follow a cohort of people who differ by certain factors (e.g. smokers and non-smokers) to study which medical conditions appear in what part of the cohort (e.g. after 20 years more smokers than non-smokers have developed lung cancer). Retrospective studies study a cohort after a medical condition (e.g. lung cancer) has occurred in a part of the group to trace back which factors (e.g. smoking) may have contributed to this.
A confounding factor is a factor that influences the relationship between variables that are investigated. In dietary research, for example, a lack of physical exercise may potentially confound the association between the consumption of soda beverages and overweight: when those who drink the most soda beverages are generally more overweight, but also exercise less, the association between the consumption of soda beverages and overweight may be caused partly or entirely by a lack of exercise. Other common confounding factors include age, gender, whether people smoke or drink alcohol, occupation, educational attainment, or income. Confounding factors are a potential bias in statistical research and may lead to over- or under-estimating the relationship between variables. While theoretically their number can be infinite, statistical research often accounts for a set of known potential confounding factors.
The concept of the ‘corporate food regime’ was developed by political economist Phillip McMichael, in his work identifying different historical phases in the political economy of food and agriculture. He characterises the period from the late 1980s onwards as the ‘corporate food regime’ due to the increasingly prominent role played by large transnational corporations in all aspects of food provisioning, including through their influence on market prices and the establishment of new regulations and trade policies. The idea is widely used by academics, particularly proponents of food sovereignty, to critically refer to the various actors and processes that facilitate the dominance of an export-led global food system.
Cover crops are crops that are grown with the purpose of protecting or improving the soil, rather than for harvest. Cover cropping can prevent soil erosion, improve soil fertility and quality, and help prevent pests and diseases. This practice can reduce the need for chemical inputs and is commonly associated with agroecology, regenerative agriculture and organic farming.
Crop rotation is the practice of growing different types of crops in sequence across the same area of land. It is designed to optimize nutrients in the soil, improve soil health, and counter pressure from pests and weeds. This practice can reduce the need for chemical inputs and is commonly associated with agroecology, regenerative agriculture and organic farming.
Crop-livestock integration refers to the practice of combining the cultivation of one or more crop with at least one type of livestock. This integration is designed to reduce reliance on external inputs, as the crops provide feed for the animals, and the animal manure provides nutrients that foster crop production. Integrated crop-livestock farming is associated with agroecology, regenerative agriculture and organic farming.
Decoupling refers to the idea of disconnecting the growth of gross domestic product (GDP) from increases in environmental impacts – climate change in particular. The term is sometimes used more broadly in relation to overall human well-being rather than GDP. The idea of decoupling is based on the understanding that economic growth often goes hand in hand with increases in environmental impacts. Advocates of decoupling think that advances in technology will provide ways of fostering economic growth without increasing the use of resources or the generation of environmental impacts, and without requiring radical shifts in aspirations as to what constitutes a ‘good’ standard of living. Decoupling can be used both in a relative sense (e.g. a lower ratio of environmental impacts versus GDP) and in an absolute sense (i.e. the overall amount of environmental impacts is reduced). Relative decoupling is sometimes criticised for being open ended and thereby failing to speak to the need of keeping production and consumption levels within environmental limits. In general, critics question whether decoupling (both relative and absolute) is feasible for diverse reasons: because of the possibility of rebound effects; because it is unlikely to be possible to separate the production of goods and services from resource use (and the impacts of this resource use) to the degree that is necessary; and because the growth-based economic paradigm on which faith in decoupling is based fails to challenge the potential insatiability of human demand – an insatiability which (it is argued) lies at the root of our environmental crisis.
Deforestation is the clearance of forest or standing trees from land as it is converted to non-forest use. Deforestation can include the conversion of forest land to ranches or other agricultural activities. Important drivers of deforestation are the use of land for agriculture, ranching, infrastructure, urban expansion, and mining. Deforestation is often defined in relation to a cut-off date – e.g. all forest land cleared after June 2008 could be considered to be deforestation. Deforestation is a particular form of land use change. The concept is not commonly used to refer to types of land use change where other areas that may contain native vegetation (e.g. hay, marshes, savannas) are converted.
Deforestation risk is a concept used by supply chain transparency initiatives such as Trase to express the amount of deforestation or clearance of native vegetation after a certain cut-off date that can be linked to a particular batch of soy or another commodity. The deforestation risk is calculated as the number of hectares that is cleared of native vegetation in a particular region per tonne of yield, and is assigned to a trader or country on the basis of the amount of product it sources from that specific region. If a buyer sources 500 t soy from a region that produces 1000 t and where 800 ha of deforestation can be linked to soy production, the buyer faces a deforestation risk of 400 hectares (50% of the total) in this region.
The term 'dietary survey' refers to a group of methods that are used to collect food consumption data to study the diets of individuals or groups. Common methods in dietary surveys are food frequency questionnaires, food diaries, and 24-hour recalls. These are often combined with the weighing and analysis of food to determine its nutritional properties. Dietary surveys are sometimes combined with other methods (e.g. the measurement of BMI or blood values) to study the relations between certain dietary patterns and health outcomes. National dietary surveys, conducted and commissioned by national and international health authorities, study national dietary patterns and are often an important input for the development of food policy.
Disability-Adjusted Life Years (DALYs) are a way of measuring the burden of ill health. One DALY can be thought of as one lost year of healthy life. Across a population, DALYs are calculated by adding together years of life during which illness is experienced, weighted according to the severity of the illness, and years of life lost to premature mortality.
Dumping refers to the practice of exporting products at a price lower than the normal price (e.g. the price in the domestic market of the exporter, or the price in the market of a third country), in order to increase market share and drive out competition. It is a highly controversial practice as it tends to support farmers in rich countries at the expense of producers and consumers in low-income countries. Although it is legal under World Trade Organisation rules, it has been heavily criticised, particularly by the food sovereignty movement, for undermining domestic production and food security in the global South, and marginalising smallholder farmers in the global economy.
Ecological intensification is the principle of using the natural functionalities of an ecosystem to produce greater amounts of food, fibre, and fuel in sustainable ways. Underpinning EI is the idea that ecological functions (e.g. pollination and predator/prey relationships) can be integrated into agricultural practices, ideally leading to ‘agroecosystems’ that are sustained by natural processes and avoid many negative environmental impacts. Ecological intensification is closely related to the concepts of sustainable intensification and climate smart agriculture, but differs in its strong focus on the potential of enhancing ecological processes in food production.
Ecosystem services are the tangible and intangible benefits that are provided by ecosystems to humans, which both enable human life and that contribute to its quality. Ecosystem services include provisioning services such as food and water; regulating services such as flood and disease control; cultural services such as spiritual, recreational, and cultural benefits; and supporting services such as nutrient cycling that maintain the conditions for life on Earth.
Ecotoxicity refers to the toxicology of pollutants in the environment. The study of ecotoxicology includes consideration of the interaction of pollutants both with abiotic aspects of the environment - soil, air and water; and how they interact with living systems, at the level of cell, organ, and organism to communities and ecosystems.
Endemic species is a plant or animal species that is unique to a specific geographic location, such as a country or an island. Usually the area where an endemic species live is isolated, making it difficult for the species to move to other areas. Endemic species are often uniquely adapted to the specific environment in which they live. Almost all endemic species are specialist species.
Enteric fermentation is a natural part of the digestive process of ruminant animals (e.g. cattle and sheep) where microbes decompose and ferment the food present in large rumen portion of the stomach. As a byproduct of this fermentation process, some bacteria species in the stomach produce methane.
Epidemiology is a scientific discipline that uses data mathematical tools to understand the patterns of disease found in human populations and changes therein. It seeks to explain exactly how these patterns are caused in order to identify ways to control and treat health problems.
Eutrophication refers to the buildup of nutrients in a body of water (e.g. nitrogen and phosphorus) to a level in excess of what would occur naturally and to which aquatic ecosystems are adapted. This can result in detrimental impacts on many aquatic plants and animals, as well as the rapid overgrowth of some plants and algae.
Farmer field schools allow farmers to acquire skills and knowledge through participatory and hands-on learning. They are designed to facilitate experimentation and discussion amongst farmers and to encourage the uptake of more sustainable production practices. This approach is favoured by the UN FAO, and has long been an important feature of agroecology movements.
Feed conversion efficiency is a measure of how much feed is required to produce a certain amount of a desired output. Such outputs may be animal weight, the amount of milk or meat produced, or even nutritional value measured in calories or grams of protein. It is a metric used to compare animal breeds and species in terms of their ability to convert feed into food available for human consumption.
Food additives, including colourants, flavour enhancers, sweeteners, emulsifiers, and preservatives, are substances that are added to foods to preserve them or to enhance their taste and appearance. A food additive may have nutritional value but is not normally consumed as a food by itself. Generally not considered to be food additives are herbs, spices and substances such as micronutrients (for example iron or vitamin B12) that are added solely to improve a food’s nutritional qualities. Many food additives have a long history and are derived from food ingredients or non-food substances that have traditionally been used for processing foods (e.g. chalk or beetroot juice colourant). Others are produced using chemical synthesis (e.g. aspartame and synthetic vitamins). Some question the health impacts of certain additives from this latter group. Many national and international health authorities regulate additives by banning their use and by defining intake limits.
The food chain is a hierarchical network constituted by the succession of organisms that eat other organisms and may, in turn, be eaten themselves. The position an organism occupies in a food chain is indicated by its trophic level. Plants, algae, and phytoplankton constitute the lowest trophic level, whereas predators and carnivores constitute the highest trophic levels. Many humans consume food from different trophic levels, while those following vegetarian and vegan diets consume all or most of their food from the primary trophic level.
A food frequency questionnaire is a dietary assessment tool commonly used in nutrition research that consists of a questionnaire in which participants are asked to answer questions relating to the frequency with which they consumed certain foods and drinks during a selected time period, e.g. a week, month or year. Food frequency questionnaires can be long or short and interviewer- or self-administered. They are commonly used to investigate the dietary patterns of large populations, and unlike 24-hour recalls, they can measure the consumption of foods that are eaten incidentally or occasionally. Limitations of food frequency questionnaires include their reliance on participants’ ability to accurately recall the foods and drinks they have consumed over a relatively long period, and the possibility of social desirability bias (e.g. people may over-report their consumption of foods they think are healthy or sustainable).
Food justice is defined as the right of communities everywhere to produce, process, distribute, access, and eat good food regardless of race, class, gender, ethnicity, citizenship, ability, religion, or community. The food justice movement emerged in the 1990s in the US, primarily amongst Black and ethnic-minority urban communities, to highlight in particular the racialised nature of inequalities within the food system.
Food preservation encompasses the processes and techniques that are used to prevent food from spoiling, including canning, pickling, salting, drying, smoking, chilling, fermenting, pasteurising, and the addition of chemicals such as sodium benzoate (which dissolves in food as an acid). These measures inhibit the growth and survival of microorganisms that spoil food. Food preservation can be understood as a form of food processing.
Food processing, defined by stakeholders in many different ways, broadly refers to modifications made to raw food ingredients after they have been gathered or harvested and before they are consumed or prepared for consumption in a kitchen. Examples of food processing include the pickling of vegetables, smoking or mincing of meat, pasteurisation of milk, milling of wheat, and the hydrogenation of oils. By this definition, most foods are processed in some way (e.g. to improve their taste, extend their shelf-life, make them edible or increase their nutritional value), but there are growing concerns over the health impacts of industrially processed foods.
Food sovereignty is a political movement that emphasises the rights of food producers, distributors and consumers to have control over the food system, as opposed to coorporations and market institutions. It has been defined as the right of peoples to healthy and culturally appropriate food produced through ecologically sound and sustainable methods, and their right to define their own food and agriculture systems.
Fortification refers to the addition of micronutrients to foods to improve their nutritional quality. For example, micronutrients such as iron, zinc, or vitamins A and B may be added to rice or white bread. Fortification is seen as a way of improving the nutritional status of a population.
A functional unit refers to the product, service, or system whose impacts are calculated by a life-cycle assessment (LCA). Common examples of food-related functional units are 1 kg of beef, 100 calories of food, or 1 ha of land. The choice of functional unit influences an LCA’s results and care is needed when comparing the results of LCAs with different functional units. The functional unit is defined in the first phase of a life-cycle assessment study – that of goal and scope definition.
A generalist species is a plant or animal species that is able to thrive in a large variety of environmental conditions, or that can live on a wide variety of foods. Members of the same generalist species can often be found at different parts of landscapes and in different regions of the world.
Global warming potential (GWP) refers to quantifying the strengths of different greenhouse gas emissions relative to carbon dioxide (CO2). Derived from estimating the total change in atmospheric energy balance resulting from a pulse emission of the gas, relative to CO2, over a specified time-frame (typically 100 years).
The Green Revolution was an agricultural modernisation programme in the 1950s and 1960s that promoted the widespread adoption of fertilisers and pesticides, agricultural machinery and higher-yielding varieties of maize, wheat and rice around the world, particularly in Latin America and Southeast Asia. It was led by the US government along with the Rockefeller Foundation and the Mexican government, and was further promoted by development agencies, agronomists, and policy makers. Different reasons are attributed to its widespread promotion, including concerns about increasing food supplies to meet the demands of a growing global population, worries about rural unrest in the context of the Cold War, and a desire to expand farm input markets. The impacts of the Green Revolution are a topic of much debate. Proponents who seek a new 21st century Green Revolution highlight its role in increasing agricultural yields in Asia and Latin America; critics, on the other hand,emphasise that it did not effectively tackle hunger and malnutrition and that it resulted in environmental degradation, serious social inequalities and unhealthy dietary change.
GWP* is an alternative application of Global Warming Potential to derive carbon dioxide equivalents (referred to as CO2e* if using GWP*) that primarily relates the change in the rate of short-lived greenhouse gases (such as methane) to a fixed quantity of CO2, rather than a direct equivalence between emissions of both short- and long-lived greenhouse gases, as is the case for conventional use of the 100-year Global Warming Potential.
Hydrogenation is a chemical reaction between a hydrogen molecule (H2) and another molecule or element in the presence of a catalyst such as palladium, platinum or nickel. In the food industry, hydrogenation is often used to turn liquid oils into solid fats. The partial hydrogenation of oils is used to produces trans-fats. Hydrogenated fats and trans-fats are contested for their health impacts.
Hydroxyl (OH) radicals are highly reactive molecules responsible for the initial reaction leading to most methane destruction in the atmosphere, and also important for the removal of many other atmospheric pollutants. Radicals are molecules or atoms with an unpaired electron, often making them very reactive.
Industrial food manufacturing refers to the large-scale production of food products by processing companies using highly mechanised assembly lines and according to pre-defined specifications that guarantee the production of a product with a constant quality. Most of these foods are produced for the retail and consumer market.
Intensification refers to a process by which farming systems (for crops or livestock) are reorganised – often through the application of new technologies, economies of scale, and the use of additional inputs, such as nutrients, chemicals, energy and water – in order to produce more of a desired output (e.g. meat) while using less land, human labour, or capital. The result is that the costs of production for a given amount of food are reduced, thereby increasing profits through larger profits per unit of food, or by expanding total consumption through lower prices, enabling more people to buy more. Often, environmental impacts per unit of product are also reduced, but may be counterbalanced by increases in total production. The impacts of intensification processes on animal welfare, biodiversity, and other issues is also a widely held concern.
Intensive agriculture (IA) is often used synonymously with the terms industrial agriculture and conventional farming. IA is generally used to denote farming systems that use modern technologies and economies of scale to maximise yields relative to land use and production costs (e.g. costs of labour, technology, seeds, fertilisers, and pesticides). IA is associated with high use of chemical fertilisers, agrochemicals, and irrigation. This combination of agricultural technologies became common during the Green Revolution in the mid-20th century and has long been criticized for its high social and environmental impacts.
The Intergovernmental Panel on Climate Change (IPCC) is the international body for assessing the science related to climate change. It is administered by the United Nations with participation and decision making from 195 member states. The assessments that it produces provide the basis for government at all levels to create climate related policies.
Iso-calorific is a term that means to hold the amount of calories in a diet constant, while changing other variables. It is used in research as a way to make meals with different compositions in terms of foods and nutrients, equivalent and comparable in terms of the energy that they provide.
Isotopic signature refers to the ratio of different isotopes. Isotopes are atoms that have a different number of protons and neutrons. For example, most carbon (C) has 6 protons and 6 neutrons, giving it an atomic weight of 12. This form of carbon is known as carbon-12 (or 12C). Another stable form of carbon exists with 6 protons and 7 neutrons, giving it a molecular weight of 13, hence it is known as carbon-13 (or 13C). Different sources of methane emissions can be composed of different proportions of 12C and 13C, with fossil fuel sources often containing relatively more 13C than biological sources.
La Via Campesina (LVC) is a transnational social movement, made up of 200 million people across 81 nations. It was formed in 1993 by peasants and smallholder farmers from around the world in response to the negative impacts of trade liberalisation and diminishing state support for small-scale agriculture. It has since grown to include landless people, rural women and youth, indigenous people, migrants and agricultural workers. LVC has played a key role in the food sovereignty movement, leading protests against global free trade agreements and promoting agroecology and smallholder farming. LVC has a decentralised structure, made up of multiple autonomous organisations, and prioritises inclusivity and democratic decision making.
Land sharing is the principle of integrating nature conservation approaches into agricultural production across a region. Its characteristics are that of low-yielding farmland with higher biodiversity, but with less land available for the sole purpose of nature conservation. Land sharing sits at one end of the two extremes of the land sparing-sharing continuum. It has in particular been criticised for leading to lower levels of biodiversity on a regional scale and for a tendency for generalist species to thrive at the expense of specialist or endemic species.
Land sparing is the principle of segregating land for nature conservation from land for food (or agricultural) production within a region. It consists of high-yielding farmland with relatively lower biodiversity, with the remaining land being spared for nature conservation. Land sparing sits at one end of the two extremes of the land sparing-sharing continuum. It has in particular been criticised for its (supposed) connection to environmentally unsustainable intensive agriculture and for undermining the food security of smallholder farmers and rural economies.
Life cycle, in the context of life-cycle assessment and carbon footprint analysis, refers to the entirety of phases a product or system passes through from its development, through to its use and, eventually, how it is managed as waste. A life cycle is generally understood to start at the growing and harvesting or mining of raw materials and to end when a product is disposed of as waste. While waste management is thought to be a part of a product’s life cycle, potential recycling is generally considered to be part of the life cycles of other, new products. For example, the life cycle of a loaf of bread may be thought to consist of the following phases: the growing and harvesting of corn and other ingredients (including pre-production of inputs such as fertilisers), their transport to a bakery, bread production, transport and retail, consumption and waste.
Malnutrition refers to deficiencies, excesses, or imbalances in the energy, macronutrients, or micronutrients that a person obtains. This is either because their diet is lacking or because their body is not able to fully absorb the nutrients from the foods eaten, e.g. due to illness. Malnutrition is an umbrella term that includes overnutrition (an excess of food energy), undernutrition (a lack of food energy and macronutrients such as protein), and micronutrient deficiencies (insufficient micronutrients such as iron, vitamin A or iodine).
A mangrove is a salt tolerant tree or shrub that grows in tidal and coastal wetlands and swamps, typically in tropical and sub-tropical regions. They typically form mangrove forests and are globally important for biodiversity and carbon storage, and also for their role in coastal protection.
A Mediterranean diet is an idealised dietary pattern that has commonalities with the diets traditional to many Mediterranean countries. It is a diet that is primarily based on vegetables, fruits, pulses, nuts, cereals, olive oil, and fish, with moderate consumption of dairy and low to moderate amounts of meat. Mediterranean type diets are considered to have health conferring benefits.
Micronutrient deficiencies result from a diet lacking the essential vitamins and minerals that humans require in small amounts for proper growth, development, and bodily functioning. These include iodine, calcium, iron, zinc, and vitamins A, B, and C, among others. Micronutrient deficiencies are the cause of a range of diseases affecting physical and mental development, and can increase susceptibility to infectious diseases.
Micronutrients are minerals (e.g. iron) and organic compounds (e.g. vitamin A) found in food, which the body requires in very small amounts to produce substances such as enzymes and hormones. They are essential for proper growth, development and bodily functioning. Essential micronutrients are those that cannot be synthesised by the body and so must be obtained through diet.
Minimally processed food is a category of foods in the NOVA classification that have not been processed (e.g. fresh fruits and vegetables) or that have been modified only minimally by processes such as drying, roasting, boiling, freezing, and the removal of inedible parts. Advocates of NOVA understand minimally processed foods to be processed to extend their lifetime, enable their storage, make them easier to prepare, or to increase the number of ways they can be consumed. Examples include fresh meat and vegetables, whole wheat grains, wholemeal flour, ground coffee and pasteurised milk.
A monogastric is a mammals with a single-compartmented stomach. Examples of monogastrics include humans, poultry, pigs, horses, rabbits, dogs and cats. Most monogastrics are generally unable to digest much cellulose food materials such as grasses. Herbivores with a monogastric digestion system (e.g. horses and rabbits) are able to digest cellulose in their diets through microbes in their gut, but they extract less energy from these foods than do ruminants. A major proportion of the feed given to monogastrics reared in intensive systems comprises human edible grains and soybeans.
Neoliberalism is an ideology and a political and economic policy model that emphasises the importance of freedom from state intervention, the privatisation of public goods, and the primacy of economic growth and free market competition. Neoliberal policies were championed in the 1980s by US President Ronald Reagan and UK Prime Minister Margaret Thatcher – these policies included cuts to state spending and efforts to promote economic growth by privatising public services and deregulating the corporate sector. Neoliberal thinking has since gained traction amongst many national and global policy makers, and in the 1980s and 1990s led by the World Bank and International Monetary Fund to promote economic restructuring in countries around the world. More recently however, neoliberalism has received various levels of criticism. The 2008 financial crisis for example has prompted many economists and policymakers to call for greater government regulation of the financial and banking sectors. Although neoliberalism is recognised for increasing the wealth of certain portions of the world’s population, it has also been responsible for widening socio-economic inequalities and worsening climate and environmental crises. Debates about the value of economic growth and the ability of markets to efficiently and fairly allocate resources are therefore ongoing.
Nitrogen fixation is the process through which atmospheric nitrogen (N2) is converted into ammonia (NH3) or related nitrogenous compounds that, when present in the soil, can be utilised by plants. Plants are unable to utilise atmospheric nitrogen (N2) for plant growth because it is a relatively unreactive gas. There are two main processes through which nitrogen fixation occurs in the food system: artificial nitrogen fixation through the Haber-Bosch process – the process underlying the production of synthetic fertiliser – and biological nitrogen fixation (BNF) through bacteria in the soil and roots of particular plant and tree species such as legumes.
Non-communicable diseases are diseases which are not passed from person to person. They are often long lasting and generally progress slowly. Examples include cardiovascular diseases, cancer, chronic respiratory diseases and diabetes. Unhealthy diets are one of the major risk factors for non-communicable diseases.
The NOVA classification is a system of food classification created by a team of nutrition and health researchers at the University of São Paulo led by Carlos Monteiro. NOVA categorises food products by the ‘extent’ and ‘purpose’ of food processing on the grounds that today this is the main determinant of a food’s nutritional and environmental characteristics. NOVA has four categories: minimally processed food; processed culinary ingredients; processed foods; and ultra-processed foods. Introduced as a framework to measure the impacts of processed foods on human health, NOVA has also been promoted as an alternative to traditional government-approved dietary guidance such as the US MyPlate, the UK Eatwell plate or the Chinese Food Pagoda. While criticised, NOVA is increasingly used as a framework in nutrition science, especially in nutritional epidemiology. The dietary guidelines of Brazil (2014), Uruguay (2016), Ecuador (2018) and Peru (2019) and some reports from the PAHO-WHO have drawn upon the NOVA classification while the French (2019) dietary recommendations advise to reduce the consumption of ‘ultra-transformed’ foods.
Nudge approaches are the specific application of nudge theory, whereby the physical or informational environment in which decision making takes place is purposefully changed in order to affect behaviour. One example is using smaller plates to subtly limit overall food consumption in canteens.
Nudge theory is a concept in behavioural science, economics, and political science which tries to achieve non-forced compliance with desired behaviours (e.g. policies). It does this through the adjustment of messaging and the context in which decisions are made, in ways that have been found to predictably affect the motives, incentives, and decision making of individuals and groups of people.
Nutritional epidemiology is a sub-branch of epidemiology. This field of study focuses on the distribution and determinants of diseases and other medical conditions in a population. Nutritional epidemiology studies the relationships between dietary patterns, nutrient intake and their impacts upon public health. Common methods in nutritional epidemiology include dietary surveys and cohort studies, by which statistical associations between (say) food consumption and medical conditions such as cancer or obesity are studied.
Nutritionism, coined by the Australian academic Gyorgy Scrinis and popularised by the US journalist and food writer Michael Pollan, is a term used to describe and critique the dominant assumption of much nutrition science research – and often of mainstream dietary recommendations – that it is possible to understand the health implications of individual food products as well as dietary patterns in terms of their micro and macronutrient proﬁles. From this nutritionist perspective, foods are primarily viewed as interchangeable vehicles for the delivery of specific and isolated nutrients. Criticising ‘Big Food’ and the food products it provides, users of the concept tend to highlight the role of food in social and cultural life and argue that healthy dietary patterns mostly consist of home-made meals and dishes that are largely based on unprocessed food ingredients. Gyorgy Scrinis also argues that nutritionism has contributed to the food industry’s use of reformulation and nutrient fortiﬁcation, which are aimed at improving a food’s nutrient profile.
Organic farming is an approach to farming in which synthetic chemical insecticides and herbicides and inorganic fertilisers are entirely or largely avoided. Underpinning organic farming is the idea that farming should rely on ecological processes, biodiversity, and cycles adapted to local conditions, rather than the use of inputs with adverse effects (e.g. agrochemicals such as pesticides and synthetic fertilisers). Certification bodies (e.g. the Soil Association in the United Kingdom) specify the practices, methods of pest control, soil amendments, and so forth that are permissible if products are to achieve organic certification.
Ozone is a molecule consisting of three oxygen atoms (chemical formula O3; ‘trioxygen’). In the upper atmosphere (‘stratosphere’) ozone plays an important role in absorbing ultraviolet radiation from the sun, but is also a greenhouse gas, and at the surface has negative impacts on human health and plant growth. Ozone is also one of the by-products from atmospheric methane oxidation.
Ozone layer depletion is a decline in the level of ozone gas (O3) present in the earth's stratosphere, owing to its breakdown into oxygen (O2). This breakdown can be affected by natural processes, but is known to have been accelerated by the release of man-made chemicals, such as refrigerant gases. The ozone layer acts to reduce the amount of light at ultra-violet wavelengths reaching the earth's surface; wavelengths that can have harmful impacts on humans, including skin cancer.
A pandemic is the widespread occurrence (i.e. global or at multiple continents) of a disease during a particular period. Historically, many pandemics have involved infectious diseases that have been spread by viruses such as cholera and flu. Pandemics, however, can both be caused by communicable and non-communicable diseases.
Photochemical smog is observed as a haze in the atmosphere, typically near to cities. It is created through the action of sunlight on pollutants (nitrogen oxides and volatile organic compounds) emitted by automobiles and other industrial sources, which creates other pollutants harmful to health, such as ozone.
The planetary boundaries concept refers to the idea that humans are substantially altering natural systems, and that beyond a certain level of change this may become irreversible and self sustaining. The potential result is a planet with environmental conditions that differ substantially from those in which human civilisation developed and to which many species and ecosystems are adapted. Planetary boundaries have so far been proposed for climate change, biodiversity loss, biogeochemical cycles, ocean acidification, land use, freshwater, and ozone depletion.
Polycultures consist of cultivating two or more crops (or animal species) on the same piece of land. Polycultures are often grown in groupings that either complement their nutritional needs or growing habit. Though polycultures have long been practiced in traditional farming systems around the world, the development of farm machinery, synthetic fertilisers and pesticides and a preference for simpler, more intensive systems that lend themselves well to economies of scale led to the displacement of polycultures in many contexts. Polycultures are associated with agroecology, regenerative agriculture and organic farming and are favoured for their role in enhancing biodiversity, improving soil health and reducing the need for chemical inputs.
Precision farming is an agricultural management practice that aims to supply plants or animals with precisely the amounts of agricultural inputs (e.g. water, pesticides, and fertilisers) they need at a specific location and moment in time, thereby increasing efficiency by reducing the total inputs needed for agricultural production, and reducing environmental impacts. Precision farming uses different types of technologies to measure, observe, and act upon factors that are relevant to the growth of crops and livestock. These can range from big data, GPS, robotics, sensors, and drones, to low-tech measures such as using bottle caps for applying the right amounts of fertilisers to individual plants. Aiming to optimize crop or livestock production, precision techniques include measuring, modelling, and responding to (site-specific) data, including weather forecasts, soil properties, soil water content, pests, and weeds.
Price elasticity refers to how much the demand for a good is affected by a change in its price. A good is said to be price inelastic if a change in price means that there is little change in demand. An example might be medication or addictive substances, like tobacco. A good is said to be price elastic if a change in price greatly changes the demand for the good.
Processed culinary ingredients is a category of food ingredients in the NOVA classification that result from the further treatment of unprocessed and minimally processed foods by processes such as pressing, refining, grinding, milling, and spray drying. Examples include salt, spices, cane sugar, flour, honey and olive oil. Processed culinary ingredients are added to other foods in the preparation of dishes. Advocates of NOVA understand their purpose to be enabling the preparation of more varied dishes from minimally processed foods and improving the taste and appearance of such dishes. Processed culinary ingredients are usually not consumed on their own.
The concept of processed food, in the public understanding, is often used loosely to refer to mass-produced ready-to-eat foods such as instant flavoured noodles and soda drinks. The concept, however, also refers to one of the four categories of the NOVA classification, which classifies many of these foods as ultra-processed foods. Within NOVA’s processed food category are minimally processed foods to which one or more processed culinary ingredient has been added, and which have been further modified by processes such as smoking, salting, and canning. Advocates of NOVA understand processed foods to be produced primarily to increase the durability of minimally processed foods and to enhance the taste and appearance of such foods. Examples of processed foods include freshly made breads, pickled vegetables, salted nuts, smoked meats, and canned fish.
Public procurement refers to the acquisition of goods, services or work by public bodies such as government agencies, hospitals, and schools, or by state owned enterprises such as railways or energy providers. Such spending can represent a substantial amount of taxpayers' money and of gross domestic product in many countries, and so how it is spent is a matter of public interest. Beause of this, changing public procurement is often seen as a way in which to influence business practices.
Radiative forcing is the measure of how different factors (including greenhouse gases) change the balance between incoming and outgoing energy in the atmosphere. Expressed as the change in energy balance per unit area (in Watts per metre square; W m-2) over a given timeframe – typically contemporary compared to preindustrial conditions.
Reconstituted meat is a paste- or liquid-like meat product that is produced from ground meat. Fat and excess water are separated from the meat using a centrifuge or an emulsifier (a machine used to produce the meat into a fine and homogeneous paste or liquid of a desired thickness). Reconstituted meat is mostly used as a basis for pet food and as a supplement in some meat products for human consumption (e.g. chicken nuggets and some sausages).
Reformulation refers to changes food manufacturers make to the production recipes of processed and ultra-processed food products to improve their nutritional profile. Examples of reformulation include replacing sugar with artificial sweeteners (e.g. aspartame or sucralose) to reduce the food’s energy content or reducing the amount of salt or saturated fat in a food product.
Regenerative agriculture aims to generate farming systems that improve soil health, increase biodiversity and sequester carbon through the use of practices such as cover crops, crop rotations, minimal tillage, organic compost, agroforestry and crop-livestock integration. Many of these practices are also associated with organic farming and agroecology. Various certification schemes are being developed which will specify the processes and outcomes required for products to be classified as ‘regenerative’
The concept of resilience, in the context of food system sustainability, refers to the ability of the food system to cope with and recover from socio-economic or environmental shocks and pressures. A resilient system has a certain degree of toughness and is able to bounce back against or adapt to disturbances. A resilient food system, for example, is able to keep providing food or other outputs such as livelihoods for farmers, drinking water, and biodiversity conservation under conditions of drought, a drop in food prices, war, climate change, the spread of virus in plants or animals, and so on. Resilience can be thought of at different scale levels. For example, what may be considered as resilient on a national level may not be understood to be resilient at a farm level. While some see resilience as synchronous with sustainability, others point out that a resilient system may also be one that resists needed transformation; an unsustainable status quo may in fact be resilient to change.
Rewilding is a form of conservation aiming to build biodiversity and restore and protect ecosystems through the promotion of natural processes rather than human inputs. Rewilding typically focuses on providing connectivity between wilderness areas, and reintroducing large herbivores, predators and/or keystone species, so that they influence natural processes and interactions throughout the food chain and minimize or eradicate the need for human land management.
The right to food was initially recognised in the 1948 Universal Declaration of Human Rights. It has since been developed by the Food and Agriculture Organisation of the United Nations, who now recognise the importance of the right to adequate food, defining this as ‘regular, permanent and unrestricted access, either directly or by means of financial purchases, to quantitatively and qualitatively adequate and sufficient food corresponding to the cultural traditions of the people to which the consumer belongs, and which ensure a physical and mental, individual and collective, fulfilling and dignified life free of fear’.
A ruminant is a mammal with a four-compartmented stomach which enables it to acquire nutrients from plant-based food such as grasses, husks, and stalks. Examples of ruminants include cattle, sheep, goats, deer, giraffes, and camels. After swallowing, microbes in the ruminant’s rumen (its first stomach compartment) begin fermenting the food. This process generates fatty acids (nutrients which the ruminant absorbs through its rumen walls) and methane, which the ruminant eructs or burps. Through this process, ruminants are able to digest coarse cellulosic material which monogastrics and people cannot. Methane emissions from ruminants are a significant source of greenhouse gasses from ruminant-based livestock systems.
Sensitivity and uncertainty analysis are an integral part of any modelling process. Sensitivity analysis varies the possible values of input variables to a model in order to understand the difference that these assumptions make to results and conclusions that can be drawn. Uncertainty analysis investigates the potential effects of lack of knowledge or potential errors in the model design.
The Brazilian Soy Moratorium (SoyM) is a multi-stakeholder initiative set up in 2006 by Greenpeace, the Brazilian Association of Vegetable Oil Industries (ABIOVE), and the National Association of Grain Exporters (ANEC). It was later joined by many other companies, civil society organisations, and the Brazilian government. Signatories to the moratorium take on the voluntary commitment not to buy soybeans grown on land in the Amazon that was deforested after 22 July 2008. The soy moratorium was initially renewed annually but extended in 2019 for an indefinite period. The moratorium has caused deforestation in the Amazon to decline to about one half to one third of the rate before the moratorium. Recent years, however, have seen an increase in deforestation in the Amazon. Deforestation levels were particularly high in the summer of 2019 due to an exceptional increase in forest fires. Only a small amount of the soy exported from the Brazilian Amazon is handled by traders who did not sign the Moratorium.
A specialist species is a plant or animal species that is able to thrive in only a limited variety of environmental conditions, or that has a limited diet. Unlike endemic species, populations of the same specialist species may be present at different geographical locations around the world.
Structural Adjustment Programs (SAPS) were introduced by the International Monetary Fund and World Bank in the 1980s in response to a series of economic crises in the global South. During this era, these institutions made access to loans by poor countries conditional on a set of economic policies that aimed to reduce state spending and open up their economies to international trade. Proponents of SAPs claimed that they would encourage economic growth; however they have been heavily criticised for undermining national sovereignty, deepening social inequality and further marginalising many poorer countries in the global economy.
Stunting is a medical condition where childhood growth and development is impaired as a result of inadequate nutrition, repeated infection, and inadequate psychosocial stimulation. Children are defined as stunted if their height for their age is abnormally low. Its effects can lead to an underdeveloped brain, poor cognition and educational attainment, as well as a higher risk of nutrition-related chronic diseases later in life.
The substitution effect in economics refers to the idea that as prices increase or as a product becomes scarce, people will replace such items with substitutes that are cheaper or easier to access. In the context of diets, substitution effects refer to the changes in the environmental footprint of a person's diet, according to the relative impact of foods that are substituted for one another.
Sustainable intensification is a recently developed concept that is understood in different ways by its critics and supporters. A common understanding is that it denotes the principle of increasing or maintaining the productivity of agriculture on existing farmland while at the same time, reducing its environmental impacts. Understood in this way, SI designates a goal for the development of agricultural systems but does not, a priori, favour any particular agronomic route to achieve it. It may involve the intensification of different types of agricultural inputs (e.g. of knowledge, biotechnologies, labour, machinery) and apply these to different forms of agriculture (e.g. livestock or arable; agroecological or conventional). Forms of intensification that can be called sustainable intensification must lower environmental impacts and land use, relative to yields. However, for some, to merit the term ‘sustainable’ social, economic, and ethical criteria must also be considered.
System boundaries are subjective boundaries that define what is included within the system under analysis (and so counted) and what is external to the system (and so not counted). System boundaries have multiple dimensions, including what stages are focused on (e.g. production, distribution), what inputs and outputs are measured (e.g. land, greenhouse gases), what geographic locations are included, and more.
Turbidity refers to the amount of light that can pass through water (i.e. its cloudiness), as a result of particles that are suspended within the fluid. It can vary naturally depending on location, but can have detrimental impacts on ecosystems if caused by human activity. For this reason, it is often used as an indicator of water quality.
Ultra-processed food (UPF) generally refers to one of the four categories of the NOVA food classification (see below) and are used loosely to refer to snacks and fast foods. NOVA describes UPFs as ‘industrial formulations’ of food products, typically mass-produced, that contain few ‘natural’ ingredients. Advocates of NOVA point out that UPFs consist of many additives and food-derived ingredients such as whey, protein isolates, and invert sugar, which are produced and combined through processes that are uncommon in domestic kitchens. They understand these foods to be designed so as to be so appealing that they displace the consumption of healthier, less processed foods, thereby generating high profits for their manufacturers. Foods in the UPF category include biscuits, mass-produced buns and breads, sweetened cereals, margarines and spreads, packaged snacks, ice cream, flavoured yogurts, soft drinks, powdered meals, ready-made meals, and instant sauces and stocks. Proponents of the concept have argued that the consumption of UPF is the primary driver of the global ‘pandemic’ of overweight and obesity while contributing to non-communicable diseases such as metabolic syndrome and certain cancers. It has been argued that the production and consumption of UPFs undermine social and environmental sustainability while perpetuating unequal power dynamics in the food system. Opponents of the concept have contested these claims. They argue that the concept is imprecise and groups together foods with different nutritional characteristics.
Undernutrition refers to deficiencies of a particular component of food, usually due to insufficient intake and/or absorption of that component. This usually refers to energy (often measured in calories) or macronutrients (such as protein, carbohydrates, or fat), but can also refer to micronutrients (vitamins or minerals).
The General Agreement on Tariffs and Trade (GATT) is a legal agreement introduced in 1947 to encourage international trade. Prior to the Uruguay round of negotiations, which took place between 1986 and 1994, agricultural products had been effectively exempt from GATT rules. However, the Uruguay negotiations led to the Agreement on Agriculture, which opened up agricultural markets by reducing tariffs on agricultural goods and limiting government subsidies for agricultural exports and domestic production. This agreement has been widely criticised, particularly by the food sovereignty movement, for having negative impacts on smallholder farmers and poorer countries. Following the Uruguay round of negotiations, GATT was replaced by the World Trade Organisation.
Water footprint is a metric that quantifies the amount of water used to produce each of the goods and services we use. It allows these goods and services to be compared in terms of their water impact, and so to the impact on limited water resources of consumption by individuals, organisations, and even nation states. Water footprints incorporate all the water used – i.e. unable to be used again due to evaporation or removal in products – across the full lifecycle of a produce from production through to consumption, including all inputs to production (e.g. feed crops used in pork production). It has three components: (1) green water - rainwater used in soils; (2) blue water - freshwater sources; (3) grey water - water amount needed to dilute pollution to safe levels.
Wildlife-friendly farming, while a fairly informal term, generally refers to an approach to farming that aims to support both food production and the conservation of biodiversity on farmland. Wildlife-friendly farming is associated with the use of reduced chemical and fertiliser inputs and the preservation of native vegetation (e.g. flowers, trees, and bushes) on or around farmland. Those who use the term tend to equate wildlife-friendly farming with a land sharing approach. Related although not synonymous terms include organic farming and agroecology.
The yield gap is the difference between the actual productivity of a given area of farmland and the maximum productivity that could in principle be achieved using agricultural practices, resources, and technologies that are currently available. The best yields that can be obtained locally depend on the capacity of farmers to access and use, among other things, land, seeds, water, nutrients, pest management, soils, biodiversity, and knowledge. Yield gaps are studied and measured at various scales - from the farm through to the national and global levels.
Zero-tillage farming refers to the farming of crops without disturbing the soil through tillage. Tilling methods include such activities as shovelling and ploughing or the use of cultivators to crush clods and smoothen the soil. Zero-tillage farming requires fewer machinery inputs and related energy use, and often less human labour per unit of output. Tillage is used to eliminate weeds, and zero-tillage farming is often associated with higher pesticide and herbicide levels. Zero-tillage farming is particularly associated with the production of genetically modified crops and the use of glyphosate-based broad-spectrum herbicides such as Roundup that kill many different types of weeds.