Subsistence agriculture

Most subsistence agriculture is practiced in developing countries located in tropical climates. Effects on crop production brought about by climate change will be more intense in these regions as extreme temperatures are linked to lower crop yields. Farmers have been forced to respond to increased temperatures through things such as increased land and labor inputs which threaten long-term productivity.[9] Coping measures in response to variable climates can include reducing daily food consumption and selling livestock to compensate for the decreased productivity. These responses often threaten the future of household farms in the following seasons as many farmers will sell draft animals used for labor and will also consume seeds saved for planting.[10] Measuring the full extent of future climate change impacts is difficult to determine as smallholder farms are complex systems with many different interactions. Different locations have different adaptation strategies available to them such as crop and livestock substitutions.[11] Rates of production for cereal crops, such as wheat, oats, and maize have been declining largely due to heat's effects on crop fertility.[12] This has forced many farmers to switch to more heat tolerant crops to maintain levels of productivity.[13] Substitution of crops for heat tolerant alternatives limits the overall diversity of crops grown on smallholder farms. As many farmers farm to meet daily food needs, this can negatively impact nutrition and diet among many families practicing subsistence agriculture.[14]

In this type of farming, 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.[15] While the land is left fallow the forest regrows in the cleared area and soil fertility and biomass is 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 soil erosion.[16] Shifting cultivation is called dredd in India, ladang in Indonesia and jhumming in North East India.

While shifting agriculture's 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. These farmers pair this with "slash and burn" techniques to clear additional land and (by the burning) provide fertilizer (ash). Such gardens near the homestead often regularly receive household refuse. 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.[17] 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.[18] 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.[17][19]

In intensive subsistence agriculture, the farmer cultivates a small plot of land using simple tools and more labour.[20] 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.[20]