Slash-and-burn

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Satellite photograph illustrating slash-and-burn forest clearing along the Xingu River in the state of Mato Grosso, Brazil. ISS029-E-008032 Fires along the Rio Xingu - Brazil.jpg
Satellite photograph illustrating slash-and-burn forest clearing along the Xingu River in the state of Mato Grosso, Brazil.

Slash-and-burn agriculture is a farming method that involves the cutting and burning of plants in a forest or woodland to create a field called a swidden. The method begins by cutting down the trees and woody plants in an area. The downed vegetation, or "slash", is then left to dry, usually right before the rainiest part of the year. Then, the biomass is burned, resulting in a nutrient-rich layer of ash which makes the soil fertile, as well as temporarily eliminating weed and pest species. After about three to five years, the plot's productivity decreases due to depletion of nutrients along with weed and pest invasion, causing the farmers to abandon the field and move over to a new area. The time it takes for a swidden to recover depends on the location and can be as little as five years to more than twenty years, after which the plot can be slashed and burned again, repeating the cycle. [1] [2] [3] In Bangladesh and India, the practice is known as jhum or jhoom. [4] [5] [6]

Contents

Slash-and-burn is a type of shifting cultivation, an agricultural system in which farmers routinely move from one cultivable area to another. A rough estimate is that 200 million to 500 million people worldwide use slash-and-burn. [1] [7] Slash-and-burn causes temporary deforestation. Ashes from the burnt trees help farmers by providing nutrients for the soil. [8] The technique is not scalable for large human populations. [1]

A similar term is assarting, which is the clearing of forests, usually (but not always) for the purpose of agriculture. Assarting does not include burning. [9]

History

Historically, slash-and-burn cultivation has been practised throughout much of the world. Fire was already used by hunter-gatherers before the invention of agriculture, and still is in present times. Clearings created by the fire were made for many reasons, such as to provide new growth for game animals and to promote certain kinds of edible plants.

During the Neolithic Revolution, groups of hunter-gatherers domesticated various plants and animals, permitting them to settle down and practice agriculture, which provided more nutrition per hectare than hunting and gathering. Some groups could easily plant their crops in open fields along river valleys, but others had forests covering their land. Thus, since Neolithic times, slash-and-burn agriculture has been widely used to clear land to make it suitable for crops and livestock. [10]

Large groups wandering in the woodlands was once a common form of society in European prehistory. The extended family burned and cultivated their swidden plots, sowed one or more crops, and then proceeded on to the next plot. [11]

Technique

Slash-and-burn fields are typically used and owned by a family until the soil is exhausted. At this point the ownership rights are abandoned, the family clears a new field, and trees and shrubs are permitted to grow on the former field. After a few decades, another family or clan may then use the land and claim usufructuary rights. In such a system there is typically no market in farmland, so land is not bought or sold on the open market and land rights are traditional.[ citation needed ]

In slash-and-burn agriculture, forests are typically cut months before a dry season. The "slash" is permitted to dry and then burned in the following dry season. The resulting ash fertilizes the soil [12] [13] and the burned field is then planted at the beginning of the next rainy season with crops such as rice, maize, cassava, or other staples. This work was once done using simple tools such as machetes, axes, hoes and shovels.

Benefits and drawbacks

This system of agriculture provides millions of people with food and income. It has been ecologically sustainable for thousands of years. Because the leached soil in many tropical regions, such as the Amazon, are nutritionally extremely poor, slash-and-burn is one of the only types of agriculture which can be practised in these areas. Slash-and-burn farmers typically plant a variety of crops, instead of a monoculture, and contribute to a higher biodiversity due to creating mosaic habitats. The general ecosystem is not harmed in traditional slash-and-burn, aside from a small temporary patch. Slash and burn agriculture may be thought of as a form of agroforestry. [1]

This technique is usually not suitable to produce cash crops. A huge amount of land, or a low density of people, is required for slash-and-burn. When slash-and-burn is practised in the same area too often, because the human population density has increased to an unsustainable level, the forest will eventually be destroyed. [1]

Regionally

South Asia

Tribal groups in the northeastern Indian states of Tripura, Arunachal Pradesh, Meghalaya, Mizoram and Nagaland and the Bangladeshi districts of Rangamati, Khagrachari, Bandarban and Sylhet refer to slash-and-burn agriculture as jhum or jhoom cultivation. The system involves clearing land, by fire or clear-felling, for economically-important crops such as upland rice, vegetables or fruits. After a few cycles, the land's fertility declines and a new area is chosen. Jhum cultivation is most often practised on the slopes of thickly-forested hills. Cultivators cut the treetops to allow sunlight to reach the land, burning the trees and grasses for fresh soil. Although it is believed that this helps fertilize the land, it can leave it vulnerable to erosion. Holes are made for the seeds of crops [14] such as sticky rice, maize, eggplant and cucumber are planted. After considering jhum's effects, the government of Mizoram has introduced a policy to end the method in the state. [15]

Painting by Eero Jarnefelt of forest-burning Raatajat rahanalaiset.JPG
Painting by Eero Järnefelt of forest-burning

Americas

Some American civilizations, like the Maya, sometimes used this agricultural technique.

Northern Europe

a recently burned area at the Telkkamaki Heritage Farm in Finland, demonstrating the technique. Kaskialue Kaavin Telkkamaessa (2013).JPG
a recently burned area at the Telkkämäki Heritage Farm in Finland, demonstrating the technique.

Slash-and-burn techniques were used in northeastern Sweden in agricultural systems. In Sweden the practice is known as svedjebruk . [16]

Slash-and-burn in Smaland, Sweden (1904) NMA.0043006 Skogsbruk, svedjebruk. Svedje tillhorande Anesgarden i Slatafly, Torsas socken, Smaland.jpg
Slash-and-burn in Småland, Sweden (1904)

Telkkämäki Nature Reserve in Kaavi, Finland, is an open-air museum where slash-and-burn agriculture is demonstrated. Farm visitors can see how people farmed when slash-and-burn was the norm in the Northern Savonian region of eastern Finland beginning in the 15th century. Areas of the reserve are burnt each year. [17]

Research

This type of agriculture is discouraged by many developmental or environmentalist organisations, with the main alternatives being promoted are switching to more intensive, permanent farming methods, or promoting a shift from farming to working in different, higher-paying industries altogether. Other organisations promote helping farmers achieve higher productivity by introducing new techniques. [1]

Not allowing the slashed vegetation to burn completely and ploughing the resultant charcoal into the soil (Slash-and-char) has been proposed as way to boost yields. [18]

Promoters of a project from the early 2000s claimed that slash-and-burn cultivation could be reduced if farmers grew black pepper crops between Inga trees, which they termed 'Inga alley cropping'. [19]

A method of improving the yields in a type of traditional assarting cultivation used to grow common beans in Central American called 'slash-and-cover', has been proposed, by additionally planting leguminous shrubs to act as a fallow crop after the soil is exhausted and one is ready to clear a new patch of forest. [20]

See also

Related Research Articles

Arable land Land capable of being ploughed and used to grow crops

Arable land is any land capable of being ploughed and used to grow crops. Alternatively, for the purposes of agricultural statistics, the term often has a more precise definition:

"Arable land is the land under temporary agricultural crops, temporary meadows for mowing or pasture, land under market and kitchen gardens and land temporarily fallow. The abandoned land resulting from shifting cultivation is not included in this category. Data for 'Arable land' are not meant to indicate the amount of land that is potentially cultivable."

Tillage Preparation of soil by mechanical agitation

Tillage is the agricultural preparation of soil by mechanical agitation of various types, such as digging, stirring, and overturning. Examples of human-powered tilling methods using hand tools include shoveling, picking, mattock work, hoeing, and raking. Examples of draft-animal-powered or mechanized work include ploughing, rototilling, rolling with cultipackers or other rollers, harrowing, and cultivating with cultivator shanks (teeth).

The following outline is provided as an overview of and topical guide to agriculture:

Horticulture Agriculture of plants

Horticulture is the agriculture of plants, mainly for food, materials, comfort and beauty for decoration. Horticulturists apply knowledge, skills, and technologies to grow intensively produced plants for human food and non-food uses and for personal or social needs. Their work involves plant propagation and cultivation with the aim of improving plant growth, yields, quality, nutritional value and resistance to insects, diseases and environmental stresses. They work as gardeners, growers, therapists, designers, and technical advisors in the food and non-food sectors of horticulture.

Shifting cultivation Method of agriculture

Shifting cultivation is an agricultural system in which plots of land are cultivated temporarily, then abandoned while post-disturbance fallow vegetation is allowed to freely grow while the cultivator moves on to another plot. The period of cultivation is usually terminated when the soil shows signs of exhaustion or, more commonly, when the field is overrun by weeds. The length of time that a field is cultivated is usually shorter than the period over which the land is allowed to regenerate by lying fallow. This technique is often used in LEDCs or LICs. In some areas, cultivators use a practice of slash-and-burn as one element of their farming cycle. Others employ land clearing without any burning, and some cultivators are purely migratory and do not use any cyclical method on a given plot. Sometimes no slashing at all is needed where regrowth is purely of grasses, an outcome not uncommon when soils are near exhaustion and need to lie fallow. In shifting agriculture, after two or three years of producing vegetable and grain crops on cleared land, the migrants abandon it for another plot. Land is often cleared by slash-and-burn methods—trees, bushes and forests are cleared by slashing, and the remaining vegetation is burnt. The ashes add potash to the soil. Then the seeds are sown after the rains.

Subsistence agriculture Farming which meets the basic needs of the farmer and family

Subsistence agriculture occurs when farmers grow food crops to meet the needs of themselves and their families on smallholdings. Subsistence agriculturalists target farm output for survival and for mostly local requirements, with little or no surplus. Planting decisions occur principally with an eye toward what the family will need during the coming year, and only secondarily toward market prices. Tony Waters writes: "Subsistence peasants are people who grow what they eat, build their own houses, and live without regularly making purchases in the marketplace."

Agriculture in Mesoamerica

Agriculture in Mesoamerica dates to the Archaic period of Mesoamerican chronology. At the beginning of the Archaic period, the Early Hunters of the late Pleistocene era led nomadic lifestyles, relying on hunting and gathering for sustenance. However, the nomadic lifestyle that dominated the late Pleistocene and the early Archaic slowly transitioned into a more sedentary lifestyle as the hunter gatherer micro-bands in the region began to cultivate wild plants. The cultivation of these plants provided security to the Mesoamericans, allowing them to increase surplus of "starvation foods" near seasonal camps; this surplus could be utilized when hunting was bad, during times of drought, and when resources were low. The cultivation of plants could have been started purposefully, or by accident. The former could have been done by bringing a wild plant closer to a camp site, or to a frequented area, so it was easier access and collect. The latter could have happened as certain plant seeds were eaten and not fully digested, causing these plants to grow wherever human habitation would take them.

Controlled burn technique to reduce potential fuel for wildfire through managed burning

A controlled or prescribed burn, also known as hazard reduction burning, backfire, swailing, or a burn-off, is a fire set intentionally for purposes of forest management, farming, prairie restoration or greenhouse gas abatement. A controlled burn may also refer to the intentional burning of slash and fuels through burn piles. Fire is a natural part of both forest and grassland ecology and controlled fire can be a tool for foresters.

Agroforestry Land use management system

Agroforestry is a land use management system in which trees or shrubs are grown around or among crops or pastureland. This diversification of the farming system initiates an agroecological succession, like that in natural ecosystems, and so starts a chain of events that enhance the functionality and sustainability of the farming system. Trees also produce a wide range of useful and marketable products from fruits/nuts, medicines, wood products, etc. This intentional combination of agriculture and forestry has multiple benefits, such as greatly enhanced yields from staple food crops, enhanced farmer livelihoods from income generation, increased biodiversity, improved soil structure and health, reduced erosion, and carbon sequestration. Agroforestry practices are highly beneficial in the tropics, especially in subsistence smallholdings in sub-Saharan Africa and have been found to be beneficial in Europe and the United States.

Soil conservation

Soil conservation is the prevention of loss of the top most layer of the soil from erosion or prevention of reduced fertility caused by over usage, acidification, salinization or other chemical soil contamination.

Agriculture in Madagascar

Agriculture employs the majority of Madagascar's population. Mainly involving smallholders, agriculture has seen different levels of state organisation, shifting from state control to a liberalized sector.

Agriculture in Laos

The southeast Asian country of Laos, with a landmass of 23.68 million hectares, has at least 5 million hectares of land suitable for cultivation. Seventeen percent of this land area is actually cultivated, less than 4 percent of the total area.

Agriculture in Myanmar

Agriculture in Myanmar is the main industry in the country, accounting for 60 percent of the GDP and employing some 65 percent of the labour force. Burma was once Asia's largest exporter of rice, and rice remains the country's most crucial agricultural commodity.

Chitemene

Chitemene, from the ciBemba word meaning “place where branches have been cut for a garden”, is a system of slash and burn agriculture practiced throughout northern Zambia. It involves coppicing or pollarding of standing trees in a primary or secondary growth Miombo woodland, stacking of the cut biomass, and eventual burning of the cut biomass in order to create a thicker layer of ash than would be possible with in situ burning. Crops such as maize, finger millet, sorghum, or cassava are then planted in the burned area.

Deforestation in Madagascar

Deforestation in Madagascar is an ongoing environmental issue. Deforestation creates agricultural or pastoral land but can also result in desertification, water resource degradation, biodiversity erosion and habitat loss, and soil loss.

Ecological farming

Ecological farming is recognised as the high-end objective among the proponents of sustainable agriculture. Ecological farming is not the same as organic farming, however there are many similarities and they are not necessarily incompatible. Ecological farming includes all methods, including organic, which regenerate ecosystem services like: prevention of soil erosion, water infiltration and retention, carbon sequestration in the form of humus, and increased biodiversity. Many techniques are used including no till, multispecies cover crops, strip cropping, terrace cultivation, shelter belts, pasture cropping etc.

Indigenous horticulture is practised in various ways across all inhabited continents. Indigenous refers to the native peoples of a given area and horticulture is the practice of small-scale intercropping.

Farming systems in India

Farming Systems in India are strategically utilized, according to the locations where they are most suitable. The farming systems that significantly contribute to the agriculture of India are subsistence farming, organic farming, industrial farming. Regions throughout India differ in types of farming they use; some are based on horticulture, ley farming, agroforestry, and many more. Due to India's geographical location, certain parts experience different climates, thus affecting each region's agricultural productivity differently. India is very dependent on its monsoon cycle for large crop yields. India's agriculture has an extensive background which goes back to at least 9 thousand years. In India, Agriculture was established throughout most of the subcontinent by 6000–5000 BP. During the 5th millennium BP, in the alluvial plains of the Indus River in Pakistan, the old cities of Mohenjo-Daro and Harappa experienced an apparent establishment of an organized farming urban culture. That society, known as the Harappan or Indus civilization, flourished until shortly after 4000 BP; it was much more comprehensive than those of Egypt or Babylonia and appeared earlier than analogous societies in northern China. Currently, the country holds the second position in agricultural production in the world. In 2007, agriculture and other industries made up more than 16% of India's GDP. Despite the steady decline in agriculture's contribution to the country's GDP, agriculture is the biggest industry in the country and plays a key role in the socio-economic growth of the country. India is the second-largest producer of wheat, rice, cotton, sugarcane, silk, groundnuts, and dozens more. It is also the second biggest harvester of vegetables and fruit, representing 8.6% and 10.9% of overall production, respectively. The major fruits produced by India are mangoes, papayas, sapota, and bananas. India also has the biggest number of livestock in the world, holding 281 million. In 2008, the country housed the second largest number of cattle in the world with 175 million.

Telkkämäki Nature Reserve

The Telkkämäki Nature Reserve is an open-air museum and a heritage farm in the municipality of Kaavi, in the Northern Savonia region of Finland. It covers one square kilometer.

This glossary of agriculture is a list of definitions of terms and concepts used in agriculture, its sub-disciplines, and related fields. For other glossaries relevant to agricultural science, see Glossary of biology, Glossary of ecology, Glossary of environmental science, and Glossary of botany.

References

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