Monoculture is the agricultural practice of producing or growing a single crop, plant, or livestock species, variety, or breed in a field or farming system at a time. Polyculture, where more than one crop is grown in the same space at the same time, is the alternative to monoculture. Monoculture is widely used in both industrial farming and organic farming and has allowed increased efficiency in planting and harvest.
Continuous monoculture, or monocropping, where the same species is grown year after year, can lead to the quicker buildup of pests and diseases, and then rapid spread where a uniform crop is susceptible to a pathogen. The practice has been criticized for its environmental effects and for putting the food supply chain at risk. Diversity can be added both in time, as with a crop rotation or sequence, or in space, with a polyculture.
|Diversity in time|
|Diversity in space||Low||Monoculture, one species in a field||Continuous
(rotation of monocultures)
|Sequence of monocultures|
|Higher||Polyculture, two or more species
intermingled in a field
|Rotation of polycultures||Sequence of polycultures|
Oligoculture has been suggested to describe a crop rotation of just a few crops, as is practiced by several regions of the world.
The term monoculture is frequently applied for other uses to describe any group dominated by a single variety, e.g. social monoculturalism, or in the field of musicology to describe the dominance of the American and British music-industries in Western pop music, or in the field of computer science to describe a group of computers all running identical software.
The term is used in agriculture and describes the practice of planting the same cultivar over an extended area. Each cultivar 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. In the last 40 years, modern practices such as monoculture planting and the use of synthesized fertilizers have reduced the amount of additional land needed to produce food. However, planting the same crop in the same place each year depletes the nutrients from the earth that the plant relies on and leaves soil weak and unable to support healthy plant growth. Because soil structure and quality is so poor, farmers are forced to use chemical fertilizers to encourage plant growth and fruit production. These fertilizers, in turn, disrupt the natural makeup of the soil and contribute further to nutrient depletion. Monocropping also creates the spread of pests and diseases, which have to be treated with yet more chemicals. The effects of monocropping on the environment are severe when pesticides and fertilizers make their way into ground water or become airborne, creating pollution.
In forestry, monoculture refers to the planting of one species of tree. Monoculture plantings provide great yields and more efficient harvesting than natural stands of trees. Single-species stands of trees are often the natural way trees grow, but the stands show a diversity in tree sizes, with dead trees mixed with mature and young trees. In forestry, monoculture stands that are planted and harvested as a unit provide limited resources for wildlife that depend on dead trees and openings, since all the trees are the same size; they are most often harvested by clearcutting, which drastically alters the habitat. The mechanical harvesting of trees can compact soils, which can adversely affect understory growth. Single-species planting of trees also are more vulnerable when infected with a pathogen, or are attacked by insects, and by adverse environmental conditions.
Lawns and animalsEdit
Examples of monoculture include lawns and most fields of wheat or corn. The term is also used where a single breed of farm animal is raised in large-scale concentrated animal feeding operations (CAFOs). In the United States, The Livestock Conservancy was formed to protect nearly 200 endangered livestock breeds from going extinct, largely due to the increased reliance on just a handful of highly specialized breeds.
Crops used in agriculture are usually single strains that have been bred for high yield and resistant to certain common diseases. Since all plants in a monoculture are genetically similar, if a disease strikes to which they have no resistance, it can destroy entire populations of crops. Polyculture, which is the mixing of different crops, reduces the likelihood that one or more of the crops will be resistant to any particular pathogen. Studies have shown planting a mixture of crop strains in the same field to be effective at combating disease. Ending monocultures grown under disease conditions by introducing crop diversity has greatly increased yields. In one study in China, the planting of several varieties of rice in the same field increased yields of non-resistant strains by 89% compared to non-resistant strains grown in monoculture, largely because of a dramatic (94%) decrease in the incidence of disease, making pesticides less necessary. There is currently a great deal of international worry about the wheat leaf rust fungus, that has already decimated wheat crops in Uganda and Kenya, and is starting to make inroads into Asia as well. As much of the world's wheat crops are very genetically similar following the Green Revolution, the impacts of such diseases threaten agricultural production worldwide.
In Ireland, exclusive use of one variety of potato, the "lumper", led to the great famine. It was inexpensive food to feed the masses. Potatoes were propagated vegetatively with little to no genetic variation. When Phytophthora infestans arrived from the Americas in 1845 to Ireland, the lumper had no resistance to the disease leading to the nearly complete failure of the potato crop across Ireland. Had the farmers used multiple varieties of potato, the famine may not have occurred.
Many of today's livestock production systems rely on just a handful of highly specialized breeds. By focusing heavily on a single trait (output), other traits like fertility, disease resistance, vigor, and mothering instincts are sacrificed. 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.) By studying the pedigrees of affected and carrier animals the source of the mutation was tracked to a single bull that was widely used in the industry. Note that in 1990 there were approximately 4 million Holteins in the US making the affected population around 600,000 animals.
The environmental movement seeks to change popular culture by redefining the "perfect lawn" to be something other than a turf monoculture, and seeks agricultural policy that provides greater encouragement for more diverse cropping systems. Local food systems may also encourage growing multiple species and a wide variety of crops at the same time and same place. Heirloom gardening and raising heritage livestock breeds have come about largely as a reaction against monocultures in agriculture.
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