Shifting Cultivation

If you were born into an indigenous tribe in a rainforest, chances are you would have moved around the forest a lot. You also would not have had to depend on outside sources for food. This is because you and your family would have likely practised shifting cultivation for your livelihood. Read on to learn about this agricultural system.

Shifting cultivation definition

Shifting cultivation, also known as swidden agriculture or slash-and-burn farming, is one of the oldest forms of subsistence and extensive agriculture, particularly in tropical regions (it is estimated that about 300-500 million people globally carry out this type of system)^1,2.

Shifting cultivation is a type of subsistence agriculture, i.e. crops are primarily grown to provide food for the farmer and his/her family. If there is any surplus, it may be bartered or sold. In this way, shifting cultivation is a self-sufficient system.

Traditionally, in addition to being self-sufficient, the shifting cultivation system was a very sustainable form of farming. This was because the population involved in its practice was much lower, and there was enough land for the fallow periods to be very long. However, in contemporary times, this is not necessarily so; as the population has grown, the land available has become lower.

Characteristics of shifting cultivation

Shifting cultivation and climate

Shifting cultivation is mainly practised in the humid tropical areas of sub-Saharan Africa, Southeast Asia, Central America and South America. In these regions, the average monthly temperature is more than 18^oC year-round and the growing period is characterised by 24-hour average temperatures greater than 20^oC. Further, the growing period extends to more than 180 days.

In addition, these areas typically have high levels of rainfall and year-round humidity. The rainfall in the Amazon basin in South America is more or less consistent throughout the year. In sub-Saharan Africa, however, there is a distinct dry season with 1-2 months of low rainfall.

Shifting cultivation and climate change

Burning biomass to clear the land in this agrosystem results in releasing carbon dioxide and other gases into the atmosphere. If the shifting cultivation system is in equilibrium, the released carbon dioxide should be re-absorbed by the regenerated vegetation when the land is left fallow. Unfortunately, the system is not usually in equilibrium because of either the shortening of the fallow period or the utilisation of the plot for another type of land use instead of leaving it in fallow, among other reasons. Therefore, the net emission of carbon dioxide contributes to global warming and ultimately climate change.

Some researchers have argued that the above scenario is not necessarily true and that shifting cultivation does not contribute to global warming. In fact, it has been posited that these systems are excellent at carbon sequestration. Therefore less carbon dioxide is being released into the atmosphere compared to plantation agriculture, permanent planting of seasonal crops or other activities such as logging.

Shifting cultivation crops

In shifting cultivation a wide variety of crops are grown, sometimes up to 35, on one plot of land in a process known as intercropping.

This is to optimise the nutrient usage in the soil, while also ensuring that all the nutritional needs of the farmer and his/her family are satisfied. Intercropping also prevents insect pests and diseases, helps maintain soil cover, and prevents leaching and erosion of the already thin tropical soils. The planting of the crops is also staggered so there is a consistent supply of food. They are then harvested in turn. Sometimes trees already present on the plot of land are not cleared because they may be of use to the farmer for, among other things, medicinal purposes, food, or to provide shade for other crops.

The crops that are grown in shifting cultivation sometimes vary by region. For example, upland rice is grown in Asia, corn and cassava in South America and sorghum in Africa. Other crops grown include, but are not limited to, bananas, plantain, potatoes, yams, vegetables, pineapples and coconut trees.

Fig. 3 - Shifting cultivation plot with different crops.

Shifting cultivation examples

In the following sections, let us examine two examples of shifting cultivation.

Shifting cultivation in India and Bangladesh

Jhum or jhoom cultivation is a shifting cultivation technique practised in India's northeastern states. It is practised by tribes living in the Chittagong hill region of Bangladesh, who have adapted this farming system to their hilly habitat. In this system, the trees are cut and burnt in January. The bamboo, sapling and wood are dried in the sun and then burnt in March or April, which leaves the land clear and ready to be cultivated. After the land is cleared, crops such as sesame, maise, cotton, paddy, Indian spinach, eggplant, okra, ginger, turmeric and watermelon, among others, are planted and reaped.

In India, the traditional 8-year fallow period has reduced because of the increased number of farmers involved. In Bangladesh, the threat of new settlers, the restrictions on access to the forest land, as well as the submergence of land for the damming of the Karnafuli River have also decreased the 10-20 year traditional fallow period. For both countries, this has caused a decrease in farm productivity, resulting in food shortages and other hardships.

Shifting cultivation in the Amazon basin

Shifting cultivation is common in the Amazon basin and is practised by the majority of the region's rural population. In Brazil, the practice is known as Roka/Roca, while in Venezuela, it is called konuko/conuco. Shifting cultivation has been used by indigenous communities who have lived in the rainforest for centuries. It provides the majority of their livelihood and food.

In contemporary times, shifting cultivation in the Amazon has faced a series of threats to its existence which have lessened the area over which it can be practised and also shortened the fallow period for abandoned plots. Most notably, challenges have come from the privatisation of the land, government policies which prioritise mass agricultural and other types of production over traditional forest production systems, as well as the increase in the population within the Amazon basin.

Fig. 4 - An example of slash and burn in the Amazon.