HKDSE Geography/M6/Agriculture

Shifting Cultivation
It is a type subsistence farming. It has the following characteristics:
 * Polyculture: A wide variety of crops is grown to ensure good nutrition, maintain stable food supply and preserve soil nutrients
 * Non-sedentary: They shift from place to place.
 * Low-technology: They rely on simple tools.
 * Low productivity.

To open up a new piece of rainforest, indigenous people first use the method of slash-and-burn. The trees' ashes serve as fertilisers to improve soil fertility. After growing crops for a while, the land will become infertile and unsuitable for agriculture. They will then abandon the piece of land so that vegetation can regenerate during the fallowing period. Later, they will return to the original piece of land for farming after 50-100 years.

Shifting cultivation used to be sustainable when the fallowing period was sufficiently long and allowed time for the soil to regenerate. Yet with the rise in population and decrease in forest size, the fallowing period has been greatly shortened, rendering it unsustainable: