Subsistence agriculture

In this type of agriculture, a patch of forest land is cleared by a combination of felling (chopping down) and burning, and crops are grown. After 2–3 years the fertility of the soil begins to decline, the land is abandoned and the farmer moves to clear a fresh piece of land elsewhere in the forest as the process continues.[9] While the land is left fallow the forest regrows in the cleared area and soil fertility and biomassis restored. After a decade or more, the farmer may return to the first piece of land. This form of agriculture is sustainable at low population densities, but higher population loads require more frequent clearing which prevents soil fertility from recovering, opens up more of the forest canopy, and encourages scrub at the expense of large trees, eventually resulting in deforestation and land erosion.[10] Shifting cultivation is called dredd in India, ladang in Indonesia, milpa in Central America and Mexico and jhumming in North East India.

While this ”slash-and-burn” technique may describe the method for opening new land, commonly the farmers in question have in existence at the same time smaller fields, sometimes merely gardens, near the homestead there they practice intensive ”non-shifting" techniques until shortage of fields where they can employ "slash and burn" to clear land and (by the burning) provide fertilizer (ash). Such gardens near the homestead often regularly receive household refuse, and the manure of any household, chickens or goats are initially thrown into compost piles just to get them out of the way. However, such farmers often recognize the value of such compost and apply it regularly to their smaller fields. They also may irrigate part of such fields if they are near a source of water.

In some areas of tropical Africa, at least, such smaller fields may be ones in which crops are grown on raised beds. Thus farmers practicing ”slash and burn” agriculture are often much more sophisticated agriculturalists than the term "slash and burn" subsistence farmers suggests.

In this type of farming people migrate along with their animals from one place to another in search of fodder for their animals. Generally they rear cattle, sheep, goats, camels and/or yaks for milk, skin, meat and wool.[11] This way of life is common in parts of central and western Asia, India, east and southwest Africa and northern Eurasia. Examples are the nomadic Bhotiyas and Gujjars of the Himalayas. They carry their belongings, such as tents, etc., on the backs of donkeys, horses, and camels.[11] In mountainous regions, like Tibet and the Andes, yak and llama are reared. Reindeer are the livestock in arctic and sub-arctic areas. Sheep, goats, and camels are common animals, and cattle and horses are also important.[11][12]

In intensive subsistence agriculture, the farmer cultivates a small plot of land using simple tools and more labour.[13] Climate, with large number of days with sunshine and fertile soils permits growing of more than one crop annually on the same plot. Farmers use their small land holdings to produce enough, for their local consumption, while remaining produce is used for exchange against other goods. It results in much more food being produced per acre compared to other subsistence patterns. In the most intensive situation, farmers may even create terraces along steep hillsides to cultivate rice paddies. Such fields are found in densely populated parts of Asia, such as in the Philippines. They may also intensify by using manure, artificial irrigation and animal waste as fertilizer. Intensive subsistence farming is prevalent in the thickly populated areas of the monsoon regions of south, southwest, and southeast Asia.[13]