The Environmental Impact of Slash and Burn Agriculture

The Environmental Impact of Slash and Burn Agriculture Slash and burn agriculture- also known as swidden or shifting agriculture- is a traditional method of tending domesticated crops that involves the rotation of several plots of land in a planting cycle. The farmer plants crops in a field for one or two seasons  and then lets the field lie fallow for several seasons. In the meantime, the farmer shifts to a field that has lain fallow for several years  and removes the vegetation by cutting it down and burning it- hence the name slash and burn. The ash from the burned vegetation adds another layer of nutrients to the soil, and that, along with the time resting, allows the soil to regenerate. The Best Conditions for Slash and Burn Agriculture Slash and burn agriculture  works best in low-intensity  farming situations when the farmer has plenty of land that he or she can afford to let lay fallow, and it works best when crops are rotated to assist in restoring the nutrients. It has also been documented in societies where people maintain a very broad diversity of food generation; that is, where people also hunt game, fish, and gather wild foods. Environmental Effects of Slash and Burn Since the 1970s or so, swidden agriculture has been described as both a bad practice, resulting in the progressive destruction of natural forests, and an excellent practice, as a refined method of forest preservation and guardianship. A recent study conducted on historical swidden agriculture in Indonesia (Henley 2011) documented the historical attitudes of scholars towards slash and burn and then tested the assumptions based on more than a century of slash and burn agriculture. Henley discovered that the reality is that swidden agriculture can add to deforestation of regions  if the maturing age of the removed trees is much longer than the fallow period used by the swidden agriculturalists. For example, if a swidden rotation is between 5 and 8 years, and the rainforest trees have a 200-700 year cultivation cycle, then slash and burn represents one of what may be several elements resulting in deforestation. Slash and burn is a useful technique in some environments, but not in all. A  special issue of Human Ecology  suggests that the creation of global markets is pushing farmers to replace their swidden plots with permanent fields. Alternatively, when farmers have access to off-farm income, swidden agriculture is maintained as a complement to food security (see Vliet et al. for a summary). Sources Blakeslee DJ. 1993. Modeling the abandonment of the Central Plains: Radiocarbon dates and the origin of the Initial Coalescent. Memoir 27, Plains Anthropologist 38(145):199-214. Drucker P, and Fox JW. 1982. Swidden didn make all that midden: The search for ancient Mayan agronomies. Journal of Anthropological Research 38(2):179-183. Emanuelsson M, and Segerstrom U. 2002. Medieval slash-and-burn cultivation: Strategic or adapted land use in the Swedish mining district? Environment and History 8:173-196. Grave P, and Kealhofer L. 1999. Assessing bioturbation in archaeological sediments using soil morphology and phytolith analysis. Journal of Archaeological Science 26:1239-1248. Henley D. 2011. Swidden Farming as an Agent of Environmental Change: Ecological Myth and Historical Reality in Indonesia. Environment and History 17:525-554. Leach HM. 1999. Intensification in the Pacific: A critique of the archaeological criteria and their applications. Current Anthropology 40(3):311-339. Mertz, Ole. Swidden Change in Southeast Asia: Understanding Causes and Consequences. Human Ecology, Christine Padoch, Jefferson Fox, et al., Vol. 37, No. 3, JSTOR, June 2009. Nakai, Shinsuke. Analysis of Pig Consumption by Smallholders in a Hillside Swidden Agriculture Society of Northern Thailand. Human Ecology 37, ResearchGate, August 2009. Reyes-Garcà ­a, Victoria. Ethnobotanical Knowledge and Crop Diversity in Swidden Fields: A Study in a Native Amazonian Society. Vincent Vadez, Neus Martà ­ Sanz, Human Ecology 36, ResearchGate, August 2008. Scarry CM. 2008. Crop Husbandry Practices in North America’s Eastern Woodlands. In: Reitz EJ, Scudder SJ, and Scarry CM, editors. Case Studies in Environmental Archaeology: Springer New York. p 391-404.