What Is Slash And Burn Agriculture?

Forest patches cleared of vegetation by burning as part of slash and burn agricultural practices in Aceh, Sumatra, Indonesia
Forest patches cleared of vegetation by burning as part of slash and burn agricultural practices in Aceh, Sumatra, Indonesia
  • While deforestation can be harmful to the environment, slash and burn agriculture is actually very sustainable
  • Shifting cultivation allows natural habitats to remain, and maintains biodiversity while still yielding crops
  • Sustainable slash and burn is more commonly known as shifting cultivation, meaning crops and farming rotate in a given area to maintain the soil and natural environment

Slash and burn agriculture is a highly controversial and misunderstood practice. The practice has sometimes been associated with mass cutting, clearing and deforestation, but in fact “slash and burn” agriculture has a long standing history. The term slash and burn does sound harsh and destructive, but this farming technique, also known as shifting cultivation, can be extremely fruitful and sustainable if done correctly.The harsh cutting that is so often associated with slash and burn, is actually not at all the same practice. In the negative cases, large scale forests - often rainforests - are cut and cleared to make room for huge agricultural plots. These new farm lands are then usually planted with a single crop that is cultivated on that land until the soil is depleted of all viable nutrients. The process of shifting cultivation, however, is based on maintaining a sustainable, balanced form of farming that rotates and “shifts” within a given area, in order to allow the natural habitat to recuperate. Much like with seasons, there are various stages to this form of farming, and the process is not done in one fell swoop, cutting down entire forests and replanting them immediately.

How Does Shifting Cultivation Work?

Stubble burning
Stubble burning in slash and burn agriculture. 

Firstly, slash and burn is carefully planned, and certain areas are selected for slashing, rather than targeting an entire forest or field. This is usually around a hectare-sized piece of land. Once an area is established, trees, shrubs and large vegetation are all cut and left to dry out. After the plants have had ample time to dry, which usually takes a few days, intentional fires are set. The burning of the vegetation provides nutrients to the soil. When the trees and shrubs are burned, they break down nutrients in the dead plants, and make them more readily available to the soil. This process works much in the same way as adding fertilizer to soil before planting, except that the fertilizer in this case is natural, and coming directly from the burned plants that were already growing in that area.

Slash and burn cultivation (locally called jhum cultivation in India) in progress at Wokha, Nagaland, India

Similarly, the fire works as a natural pesticide, and thus no harmful chemicals are needed prior to planting. Once an area has been burned, it is then planted with the desired crop. Part of the shifting aspect of shifting cultivation, which is not found in other types of slashing, is that these crops are usually only planted for two growing seasons. This way, the plants benefit from the nutrient rich soil, without allowing the area to be over-used or completely depleted. 

slash and burn agricultture
Cultivation of crops in deforested area after burning in Wokha, Nagaland, India.

After the alloted growing seasons, the plot of land is then allowed to fallow, meaning it is left to regrow, and not used for agriculture or cultivated means. Over time, the natural plants of the local area will regrow, nourishing the soil and creating an organic cycle of vegetation rebirth. While one area is in fallow, cultivation and agriculture will exist in another part of the forest. This way, the cut areas have time to regrow fully, before they are used for farming again. This is also the reason it is so important that only small areas are cleared at a time, because regrowth takes many years. 

Shifting Cultivation And The Environment

palm oil
When slash and burn agriculture involves deforestation of massive tracts of forest and use of unsustainable practices, it leads to loss of biodiversity and permanent degradation of the forest quality.

One of the biggest perceived issues with slash and burn and shifting cultivation farming techniques is the negative impact on the environment. It is true that deforestation and uncontrolled slashing have had massive nad devastating impacts on ecosystems and habitats as well as greatly affected the environment at large. The removal of large expanses of trees and vegetation not only eliminates some of the world’s greatest carbon absorbers, but it has also led to erosion, soil nutrient depletion and left many areas completely barren wastelands. This drastic type of slashing is what is so often associated with slash and burn techniques, and has been argued against and ridiculed on a wide scale. However properly monitored and controlled shifting cultivation actually does not affect the environment in this way. One reason is, as mentioned above, the crops are rotated. This means that nutrients do not get depleted as rapidly or as thoroughly. When the same crop is planted in a given area season after season, the particular nutrients needed to nourish that plant are used at an increased rate. By rotating out plant crops, the soil has a chance to replenish - at least partially - between uses. Of course, for the nutrients to fully replenish, the soil does need down time, where no cultivation or agriculture occurs, which is why the most sustainable shifting agriculture involves rest periods where the ground is allowed to fallow and grow plants naturally. 

Shifting cultivation practiced in northern Thailand has damaged vast tracts of forests in the highland region.

Fallowing allows the natural environment to grow back and replenish, and thus continue a somewhat natural cycle. These areas are left for any number of years until the previously cultivated fields resemble the ‘original’ natural landscape. Only then, after years of natural, untouched use, is this area re-cut and the process allowed to start over again. 

Impact On Climate Change 

While mass cutting has been linked to climate change in a negative way, sustainable slash and burn agriculture can, in fact, be helpful. It is true that deforestation has had a large and negative effect on climate change. Because forests and trees are such large absorbers of CO2, the removal of these plants has led to an increase of carbon in the Earth’s atmosphere, which in turn has impacted the overall climate and temperature of the planet. 

With shifting cultivation, and controlled slash and burn agriculture, this negative impact is virtually nonexistent. In fact, this type of agriculture is actually much better in terms of climate change, as it is more resilient to environmental changes. Allowing fields to rest, and return to their natural state, maintains biodiversity and ensure natural habitats and plant life are not wiped out. Additionally, when smaller plots of land are farmed, and farmed in rotation, they become more resilient and resistant to environmental factors. Disease or weather can wipe out an entire crop. If expansive fields are cleared and planted with the same crop, this means the entire area - and entire yield - is at risk should it encounter disease or harsh conditions. With shifting cultivation, however, only that particular crop will be affected, meaning some agriculture may be lost, but entire areas will not be wiped out. By planting a variety of crops, they are naturally more resistant to these external forces, and all crops are able to flourish, while maintaining the natural biodiversity of the area. 


More in Environment