Farms producing only one crop at a time
In agriculture, monoculture is the practice of growing one crop species in a field at a time. Monocultures increase ease and efficiency in planting, managing, and harvesting crops short-term, often with the help of machinery. However, monocultures are more susceptible to diseases or pest outbreaks long-term due to localized reductions in biodiversity and nutrient depletion. Crop diversity can be added both in time, as with a crop rotation or sequence, or in space, with a polyculture or intercropping.
Monocultures appear in contexts outside of agriculture and food production. Grass lawns are a common form of residential monocultures. Several monocultures, including single-species forest plantations, have become increasingly abundant throughout the tropics following market globalization, impacting local communities.
Genetic monocultures refer to crops that have little to no genetic variation. This is achieved using cultivars, made through processes of propagation and selective breeding, and can make populations susceptible to disease.
Agroecological practices, silvo-pastoral systems, and mixed-species plantations are common alternatives to monoculture that help preserve biodiversity while maintaining productivity.
Agriculture.
Agricultural monocultures refer to the practice of planting one crop species in a field. Monoculture is widely used in intensive farming and in organic farming. In crop monocultures, each plant in a field has the same standardized planting, maintenance, and harvesting requirements resulting in greater yields and lower costs. When a crop is matched to its well-managed environment, a monoculture can produce higher yields than a polyculture. Modern practices such as monoculture planting and the use of synthesized fertilizers have reduced the amount of additional land needed to produce food, called land sparing. 
Note that the distinction between monoculture and polyculture is not the same as between monocropping and intercropping. The first two describe diversity in "space", as does intercropping. Monocropping and crop rotation describe diversity over "time".
Environmental impacts.
Monocultures of perennials, such as African palm oil, sugarcane, tea and pines, can change soil chemistry leading to soil acidification, degradation, and soil-borne diseases, ultimately having a negative impact on agricultural productivity and sustainability. The use of unregulated irrigation practices on popular monocultures, such as soy, can also lead to erosion and water loss. As soil health declines, use of synthetic fertilizers on monocultural fields increases, often having negative implications on human health via chemical run-off.
In addition to soil depletion, monocultures can cause significant reductions in biodiversity due to unavailability of resources, native species displacement, and loss of genetic variation. Following large-scale oil palm plantations in Latin America, research has revealed extensive declines in mammal, bird, amphibian, and pollinator diversity, particularly in Colombia and Brazil.
Due to insufficient biodiversity and population balance, monocultures are associated with higher rates of disease and pest outbreaks. In response, pesticides are widely applied to agricultural fields, further harming insect and pollinator diversity and human health. Increasing rotations of crop monocultures or using alternatives agricultural practices can help mitigate the risk of disease and attack.
Social impacts.
Environmental consequences of monocultural farming have notable social impacts, commonly concentrated to the reduction of small-scale farmers and pesticide-related health issues. Monoculture is contradictive to several primitive, more sustainable farming practices utilized by small-scale farmers. Following pest outbreaks, over 600 million liters of pesticides are sprayed annually, contaminating nearby small-scale farming and causing communal health decline. Research has revealed increased prevalence of pesticide-related disorders, diseases, and cancers affecting the human neurological, gastrointestinal, skin, and respiratory systems.
Agro-extractivism.
Agro-extractivism is a form of extractivism in which foreign territorial, political, and economical dominance over agriculture is motivated by the large-scale production and exportation of agricultural commodities, often in the form of monocultures.
Several monocultures in the Global South, such as sugar and coffee, were first planted in the 1800s following European colonization. These plantations used slave labor, setting a precedent for agriculture being a field dominated by foreign entities in the rest of Latin America and the Caribbean. This social framework has shaped the oppression of Black people and smaller-scale farmers in the face of present-day land acquisition for monocultural use.
The large-scale establishment of monocultures in the tropics has led to hindrance of local small-scale farms and indigenous land rights in the forms of reduced food sovereignty, food security, land and water access, and hunting. Land privatization and pressure for monocultural expansion by larger companies takes different forms: silent evictions, violence, and reverse leasing arrangements. Introduction to global trade makes small-scale farmers vulnerable to international demand, prices, and variations in climate affecting crop production. Farmers who make contracts or take out loans with large corporations can face debt and loss of land if they fail to meet certain crop yields or profit.
Monocultures are an aspect of agro-extractivism on account of high percentages of the produced crop being exported for processing and marketing by large transnational corporations, often in developed countries. For instance, following the North American Free Trade Agreement (NAFTA), agave production increased three-fold in Mexico from 1995 to 2019 due to foreign consumption, specifically by the United States. Pararguay sees similar demands with soy crops, exporting the majority of production without nutrients returning to native soil. More than 46 million hectares of soy has been planted across South America while over half a million hectares of land are being deforested annually to make land for cultivation. Some international companies relevant in the field of agro-extractivist monocultures are Syngenta and Bayer (biotech), Los Grobo, CRESUD, El Tejar, and Maggi (landowners), and Cargill, ADM, and Bunge (grain and seed providers).
Forestry.
In forestry, monoculture refers to plantations of one species of tree. In many areas of the world, forest monocultures are planted as an efficient way to produce and harvest timber. Because timber harvest from monoculture forests is often an export-driven industry, these plantations can be a form of extractivism. Following deforestation, monoculture afforestation has become increasingly popular due to the necessity for ecosystem services, such as mitigating the effects of climate change via carbon sequestration and gas regulation. Eucalyptus, pines, and acacias are examples of popular monocultures being utilized in the tropics and the Global South following rainforest deforestation.
Environmental impacts.
While forest monocultures are efficient ways of producing timber, studies show single-species forests reduce biodiversity, causing declines in forest productivity and native tree, animal, and insect populations over time. The loss of biodiversity in forest monocultures is associated with lower forest resistance to pathogens, attack by insects, and adverse environmental conditions.
Social impacts.
Monoculture plantations have been shown to have substantial social impacts on local communities. Forest monocultures have motivated migrations across Latin America due to localized water cycle interference, declining soil health, and changes in resource availability. While industrial agriculture can increase employment opportunities, studies show forest plantations often have limited employment opportunities, with most workers coming from outside of the community. Profits made from monoculture plantations historically follow a "boom and bust" trend, temporarily benefitting the community in increased income, revenue, and quality of life until resources are exhausted, with profits rarely distributed back into the deforested land.
Environmental changes caused by monoculture forests are particularly felt among indigenous communities given their reliance and connection to the land while additionally becoming subject to land privatization. These lands are frequently acquired through land grabbing and dispossession by large companies in global trade, ultimately reducing rural land, cutting off access to locals, and changing agricultural and community dynamics.
Residential monoculture.
Lawn monoculture in the United States was historically influenced by English gardens and manor-house landscapes, but its inception into the American landscape is fairly recent. Aesthetics drove the evolution of the residential green areas, with turfgrass becoming a popular addition to many American homes. Turfgrass is a nonnative species and requires high levels of maintenance. At the local level, governments and organizations, such as Homeowner Associations, have pressured the maintenance of lawn aesthetics and influenced real estate value. Disagreements in residential maintenance of weeds and lawns have resulted in civil cases or direct aggression against neighbors.
High levels of maintenance required for turfgrass created a growing demand for chemical management, i.e. pesticides, herbicides, insecticides. A 1999 study showed that in a sample of urban streams, at least one type of pesticide was found in 99% of the streams. A major risk associated with lawn pesticide use is the exposure to chemicals within the home through the air, clothing, and furniture, which can be more detrimental to children than to the average adult.
Genetic monocultures.
While often referring to the production of the same crop species in a field (space), monoculture can also refer to the planting of a single cultivar across a larger regional area, such that there are numerous plants in the area with an identical genetic makeup to each other. When all plants in a region are genetically similar, a disease to which they have no resistance can destroy entire populations of crops. As of 2009[ [update]] the wheat leaf rust fungus caused much concern internationally, having already severely affected wheat crops in Uganda and Kenya, and having started to spread in Asia as well. Given the very genetically similar strains of much of the world's wheat crops following the Green Revolution, the impacts of such diseases threaten agricultural production worldwide.
Historic examples of genetic monocultures.
Great Famine of Ireland.
In Ireland, exclusive use of one variety of potato, the "lumper", led to the Great Famine of 1845–1849. Lumpers provided inexpensive food to feed the Irish masses. Potatoes were propagated vegetatively with little to no genetic variation. When "Phytophthora infestans" arrived in Ireland from the Americas in 1845, the lumper had no resistance to the disease, leading to the nearly complete failure of the potato crop across Ireland.
Bananas.
Until the 1950s, the Gros Michel cultivar of banana represented almost all bananas consumed in the United States because of their taste, small seeds, and efficiency to produce. Their small seeds, while more appealing than the large ones in other Asian cultivars, were not suitable for planting, meaning all new banana plants had to be grown from the cut suckers of another plant. As a result of this asexual form of planting, all bananas grown had identical genetic makeups which gave them no traits for resistance to "Fusarium wilt", a fungal disease that spread quickly throughout the Caribbean where they were being grown. By the beginning of the 1960s, growers had to switch to growing the Cavendish banana, a cultivar grown in a similar way. This cultivar is under similar disease stress since all the bananas are clones of each other and could easily succumb as the Gros Michel did.
Cattle.
Genetic monoculture can also refer to a single breed of farm animal being raised in large-scale concentrated animal feeding operations (CAFOs). Many livestock production systems rely on just a small number of highly specialized breeds. Focusing heavily on a single trait (output) may come at the expense of other desirable traits – such as fertility, resistance to disease, vigor, and mothering instincts. In the early 1990s, a few Holstein calves were observed to grow poorly and died in the first 6 months of life. They were all found to be homozygous for a mutation in the gene that caused bovine leukocyte adhesion deficiency. This mutation was found at a high frequency in Holstein populations worldwide. (15% among bulls in the US, 10% in Germany, and 16% in Japan.) Researchers studying the pedigrees of affected and carrier animals tracked the source of the mutation to a single bull that was widely used in livestock production. In 1990 there were approximately 4 million Holstein cattle in the US, making the affected population around 600,000 animals.
Benefits of genetic diversity.
Increasing genetic diversity through the introduction of organisms with varying genes can make agricultural and livestock systems more sustainable. By utilizing crops with varying genetic traits for disease and pest resistance, chances of disease outbreak decrease due to the likelihood of neighboring plants having strain-resistant genes. This can aid in increasing crop productivity while decreasing pesticide usage.
Alternatives to monoculture.
Alternatives to monoculture include the consultation of agroecology, silvo-pastoral systems, and mixed-species plantations.
Agroecology.
Agroecology consults the entire food system, considering how agricultural inputs and outputs affect social, environmental, and economic systems. Despite the recent dominance of GMO monoculture crop rotations of soy, corn, and cotton across the deforested Amazon, many Afrodescendant-run farms in Brazil continue to use traditional practices of agroecology that have the capacity to sustain the local community, environment, and economy. Ecosystem-specific ecological damage done by monocultural practices and byproducts, including the use of biocides and soil degradation, can be irreparable. However, the increasing modern prevalence of regenerative farming