Monoculture

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 while simultaneously increasing the risk of exposure to diseases or pests. 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. Monocultures of African palm oil, sugar cane, pines, and soybeans can all be particularly aggressive to environment. The practice has been criticized for its environmental effects and for having possible long term effects on agriculture and food supplies. Diversity can be added both in time, as with a crop rotation or sequence, or in space, with a polyculture. 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 is used in agriculture and describes the practice of planting the same cultivar over an extended area. 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. In crop monocultures, each cultivar has the same standardized planting, maintenance and harvesting requirements resulting in greater yields and lower costs. For example, researchers have discovered a native plant to Senegal, called Guiera senegalensis, grown next to millet increased millet production roughly 900 percent. 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. Annually planting the same crop in the same area depletes the nutrients from the earth that the plant relies on and leaves soil weak and unable to support healthy 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. Polyculture, 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 that planting a mixture of crop strains in the same field can combat disease effectively. Switching to polyculture in areas with disease conditions can 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. Humans rely heavily on a relatively small number of food crops and farm animals for food. If disease hits a major food crop - as happened during the 19th-century Irish potato famine - food supplies for large populations could come under threat. Maintaining and increasing biodiversity in agriculture could help safeguard world food-supplies. In forestry, monoculture refers to the planting of one species of tree. Monoculture plantings provide greater 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 also causes trees to be more vulnerable when they are infected with a pathogen, or attacked by insects, or affected by adverse environmental conditions. While often referring to the mass production of the same species of crop, it can also refer to planting of a single cultivar which has same identical genetic makeups to the plants around them. When all plants in a monoculture are genetically similar, a disease, to which they have no resistance, can destroy entire populations of crops. As of 2009 the wheat leaf-rust fungus occasioned a great deal of worry internationally, having already decimated wheat crops in Uganda and Kenya, and having started to make inroads into 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.