Slash-and-burn, also known as swidden agriculture or shifting cultivation, is an agricultural practice wherein natural vegetation such as forests and shrubs are cut down and burned to clear the land. Crops are then planted in the nutrient-rich soils left behind under the ashes. When that land becomes barren, a farmer shifts to another area with natural vegetation, and repeats that process again, according to Rainforest Saver. Ash from the burned woody vegetation contains calcium and magnesium, which lowers soil acidity, according to an Oregon State University study. Soil acidity hampers the yields of grain crops like maize. Slash and burn practices are also applied when large tracts of natural vegetation are to be cleared from the land to make way for the large-scale commercial cultivation of produce for exports, according to the Gale Encyclopedia of science.
History in Finland
Agriculture was first seen employed in the form of slash and burn practices around 4,000 years ago in what is now eastern Finland, according to the Natural Resources Institute, Finland (NRIF). Later, Finland became part of Sweden, remaining a Swedish possession until 1809. The Swedish government encouraged the practice in order to open the forested lands to human habitation, and subsequently to increase tax revenues for its own kingdom, according to the Overseas Development Institute. Around 3,500 years ago. permanent agriculture began to be seen all over much of the world, and small settlements sprung up alongside it. By the beginning of the 20th Century, between 50 and 75 percent of the forests in Finland had been decimated, much being do so through slash and burn agriculture, according to the University of Freiburg. Around 1915, studies showed that slash and burn was being practiced on over 4 million hectares of land per year in Finland.
Where It’s Practiced Today, and the Negative Effects
Today, an estimated 200 to 500 million people practice continue to practice slash and burn agriculture around the world. The practice is predominant in Latin America, Asia, and sub-Saharan Africa, resulting in the destruction of tropical rain forests and other biodiverse habitats globally. According to a study conducted by the World Agroforestry Center (ICRAF), 70 percent of deforestation in Africa, 50 percent in Asia, and 30 percent in Latin America occurs as a result of slash and burn agriculture. In total, 14 million hectares of tropical moist forests are destroyed every year globally. Tropical deforestation contributes to 18 percent of the current trends in global warming. It also results in destruction of diverse flora and fauna nestled in these forests, and destabilizes the watersheds. Slash and burn also results in landslides, water pollution, and soil erosion due to lack of vegetation and roots, which are needed to anchor the soil. As a result of decreased water retention capacities, eventually droughts become more likely to happen, according to the Ecologic Development Fund (EDF).
Alternatives to Slash and Burn Agriculture
In the modern day, agricultural experts have come up with a number of more eco-friendly alternatives to slash and burn agriculture. Alley cropping is an agro-forestry method wherein people plant food crops alongside and between rows of trees so as not to hinder their growth, such as intercropping maize with gliciridia sepium. The Gliciridia sepium tree also adds nutrients to the soils which are vital for maize growth. Other practices that help reduce the need for slash and burn agriculture include the diversification of food and other crops grown by crop rotation, the creation of buffer zones of native trees in an existing forest, and land reclamation by reforesting, according to EDF. In the llanos region of Colombia, where slash and burn has largely destroyed the integrity of the soils, Inga alley cropping is helping regenerate them to almost their initial conditions as they were seen when they were under the rainforest floor. This is being done by planting Inga trees which restore the soils by fixing nitrogen and recycling phosphorus. The Inga leaves that fall also mulch the soil. according to Resilience by Post Carbon Institute.