Slash-and-burn
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.
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 to a new area.
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.
The resulting ash fertilizes the soil[13][14] 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.
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 practiced 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.
When slash-and-burn is practiced in the same area too often, because the human population density has increased to an unsustainable level, the forest will eventually be destroyed.
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 podu, 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.
Cultivators cut the treetops to allow sunlight to reach the land, burning the trees and grasses for fresh soil.
Some of these groups form primarily rural communities that reside far from the larger cities of the country, living on swidden fields where slash-and-burn agriculture is still in regular use as a part of everyday life.
It spread to western Sweden in the 16th century when Finnish settlers were encouraged to migrate there by King Gustav Vasa to help clear the dense forests.
By 1710, during the conflict with Sweden, because of their suspect loyalties Norwegian authorities considered expelling them from the border area, but did not do so because it was judged they were too poor to survive if evicted.
[citation needed] Not allowing the slashed vegetation to burn completely and ploughing the resultant charcoal into the soil (slash-and-char) has been proposed as a way to boost yields.
[24][25] A method of improving the yields in a type of traditional assarting cultivation used to grow common beans in Central America 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.
