The Uma Agroforestry System Shifting cultivation. All over the world, shifting cultivation, also called swidden agriculture, has been and still is practised to manage soil fertility. Shifting cultivation involves an alternation between crops and long-term forest fallow. In a typical sequence, forest is cut and burnt to clear the land and provide ash as fertiliser or lime for the soil. Crop yields are typically high for the first few years but then fall on account of declining soil fertility or invasion of weeds or pests. The fields are then abandoned and the farmer clears another piece of forest. The abandoned field is left to fallow for several years or decades and thus has a chance to rebuild fertility before the farmer returns to it to start the process again. Shifting cultivation is often characterised by a season-to-season progression of different crops which differ in soil nutrient requirements and susceptibility to weeds and pests. For example, the Hanunoo in the Philippines plant rice and maize the first year after clearing, then root crops such as sweet potatoes, yams and cassava, and finally bananas, abaca (Musa textilis), bamboo and fruits (Conklin 1957). Shifting cultivation practices throughout the world vary immensely, but there are basically two types of systems: Partial systems, which evolve out of predominantly economic interests of the producers, e.g. in some kind of cash crop, resettlement and squatter agriculture. Integral systems, which stem from a more traditional, year-round, community-wide and largely self-contained way of life. Provided that the population pressure does not exceed the carrying capacity of the area at that level of technology, integral systems of shifting cultivation present a good equilibrium between humans and their environment.
Posted on: Sat, 15 Mar 2014 19:51:07 +0000
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