ways for cultivation

Shifting cultivation is an agricultural system in which plots of land are cultivated temporarily, then abandoned. This system often involves clearing of a piece of land followed by several years of wood harvesting or farming until the soil loses fertility. Once the land becomes inadequate for crop production, it is left to be reclaimed by natural vegetation, or sometimes converted to a different long term cyclical farming practice. This system of agriculture is often practised at the level of an individual or family, but sometimes may involve an entire village. An estimated population exceeding 250 million people derive subsistence from the practice of shifting cultivation, and ecological consequences are often deleterious, but are not as severe provided new forests are not invaded[1]. Of these cultivators, many 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.
Contents[show]
1 Terms sometimes applied
2 The political ecology of shifting cultivation
3 Stereotypes: primitive, backward, wasteful, unproductive
4 Shifting cultivation in Europe
5 Simple societies, shifting cultivation and environmental change
6 Shifting cultivation in the contemporary world and global environmental change
7 Comparison with other ecological phenomena
8 Alternative practice in the Pre-Columbian Amazon basin
9 References
10 External links
11 See also
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[edit] Terms sometimes applied
Slash and burn or "Swidden" (a historic term applied to specific forms of shifting cultivation or to one element of shifting cultivation).
Crop rotation (not a proper synonym, but in a best case a possible concomitant element of shifting cultivation).
Crop fallowing (the practice of letting a field lie fallow or unused as part of a crop rotation cycle – typically used in dryland farming)
Jhum- the term used in North East India
Agroforestry (a land-use method that allows trees to grow in crop and livestock areas, whereby these often eventually become "planned" forests)
It is called juming and jumang in INDIA

[edit] The political ecology of shifting cultivation
Shifting cultivation is a form of agriculture in which the cultivated or cropped area is shifted regularly to allow soil properties to recover under conditions of natural successional stages of re-growth. In a shifting cultivation system, at any particular point in time a minority of 'fields' are in cultivation and a majority are in various stages of natural re-growth. Over time, fields are cultivated for a relatively short time, and allowed to recover, or are fallowed, for a relatively long time. Eventually a previously cultivated field will be cleared of the natural vegetation and planted in crops again. Fields in established and stable shifting cultivation systems are cultivated and fallowed cyclically.
Fallow fields are not unproductive. During the fallow period, shifting cultivators use the successional vegetation species widely for timber for fencing and construction, firewood, thatching, ropes, clothing, tools, carrying devices and medicines. It is common for fruit and nut trees in fallows to be planted in fallow fields to the extent that parts of some fallows are in fact orchards. Soil enhancing shrub or tree species may be planted or protected from slashing or burning in fallows. Many of these species have been shown to fix nitrogen. Fallows commonly contain plants that attract birds and animals and are important for hunting. But perhaps most importantly, tree fallows protect soil against physical erosion and draw nutrients to the surface from deep in the soil profile.
The relationship between the time the land is cultivated and the time it is fallowed are critical to the stability of shifting cultivation systems. These parameters determine whether or not the shifting cultivation system as a whole suffers a net loss of nutrients over time. A system in which there is a net loss of nutrients with each cycle will eventually lead to a degradation of resources unless actions are taken to arrest the losses. In some cases soil can be irreversibly exhausted (including erosion as well as nutrient loss) in less than a decade.
The longer a field is cropped, the greater the loss of soil organic matter, the reduction in the cation-exchange-capacity and in nitrogen and phosphorus, the greater the increase in acidity, the more likely soil porosity and infiltration capacity is reduced and the greater the loss of seeds of naturally occurring plant species from soil seed banks. In a stable shifting cultivation system, the fallow is long enough for the natural vegetation to recover to the state that it was in before it was cleared, and for the soil to recover to the condition it was in before cropping began. During fallow periods soil temperatures are lower, wind and water erosion is much reduced, nutrient cycling becomes closed again, nutrients are extracted from the subsoil, soil fauna increases, acidity is reduced, soil structure, texture and moisture characteristics improve and seed banks are replenished.
No universal optimum relationship exists between the length of the cropping period and the length of the fallow period. In favourable agricultural environments, cropping periods can be longer and fallow periods shorter, than in less favourable agricultural environments. In favourable environments soil conditions at the beginning of a cropping cycle will be better and fallow successional stages will proceed faster. Nevertheless, even in the most favourable environments, it is likely that if the cropping period is extended beyond a certain point, the fallow conditions required for an adequate recovery of soils and vegetation will be jeopardized.
If the fallow period is shortened there will be less time in which the soil recovery processes and vegetation successions can take place. The length of fallow period required to prevent net loss of nutrients will again depend on the quality of the environment, which will in turn, determine the rate at which recovery occurs. But sooner or later, if the fallow period continues to be reduced, an observable change will occur in the fallow vegetation. Secondary forest may be reduced to shorter, thinner stemmed, fewer, woody bush or jungle species, bush may be reduced to scrub and tall grasses and scrub and tall grasses may be reduced to short grasses. Less directly observable, but nevertheless critical changes will also be occurring in the soil. Changes in environmental conditions that happen subsequent to either a lengthening of the cropping period or a shortening of the fallow period often result in a fall in crop yields. It is not difficult to perceive how a shifting cultivation system, once destabilized, can proceed into a vicious circle of declining yields and shortening fallows or lengthening cropping periods, which in turn lead to further degradation of environmental conditions. This process, its causes and possible solutions are discussed further below.