Farming: Soil erosion and degradation
Soil degraded and lostWhen natural vegetation is cleared and when farmland is ploughed, the exposed topsoil is often blown away by wind or washed away by rain.
Erosion due to soy production, for example, sees Brazil lose 55 million tons of topsoil every year.1 This leads to reduced soil fertility and degraded land.
Other major crops that cause soil erosion include coffee, cassava, cotton, corn, palm oil, rice, sorghum, tea, tobacco, and wheat.2
Waterways clogged & pollutedSoil carried off in rain or irrigation water can lead to sedimentation of rivers, lakes and coastal areas.
The problem is exacerbated if there is no vegetation left along the banks of rivers and other watercourses to hold the soil.4
Sedimentation causes serious damage to freshwater and marine habitats, as well as the local communities that depend on on these habitats.
For example, people living in Xingu Indigenous Park in Brazil report declines in fish numbers. This trend is attributed to changes in the courses of waterways resulting from farming-related erosion and the silt deposition this causes.5
In Central America, plantation soil run-off ends up in the sea, where it affects the Meso American Reef.
It's not just the eroded soil that is damaging: pesticides and fertilizers carried in rainwater and irrigation runoff can pollute waterways and harm wildlife.
Arable land destroyedLand degradation stretches to about 30 % of the total global land area.6
The problem persists, with a reported loss rate of about 10 million hectares per year.
In reality, the situation may be much more worrying. Over the last 5 decades, increases in agricultural productivity have made it possible to produce more crops on the same amount of land.
But the problem is that because agricultural land is often degraded and almost useless, producers keep on moving to more productive land. Globally, the land used and abandoned in the last 50 years may be equal to the amount of land used today.3
Flooding increasedErosion caused by deforestation can also lead to increased flooding. In banana plantations, for example, flooding occurs partly because of deforestation (soil is no longer there to absorb the water) and partly because of poorly constructed plantation drainage systems.
1. WWF (2006) Facts about soy production and the Basel Criteria.
2. Carey C., Oettli D. (2006) Determining links between agricultural crop expansion and deforestation. A report prepared for the WWF Forest Conversion Initiative.
3. Carey C., Oettli D. (2006) Determining links between agricultural crop expansion and deforestation. A report prepared for the WWF Forest Conversion Initiative.
4. Centre for Science in the Public Interest (2005) Cruel Oil: How palm oil harms health, rainforests and wildlife.
5. Van Gelder J.W., Dros J.M. (2006) From rainforest to chicken breast: Effects of soybean cultivation for animal feed on people and nature in the Amazon region - a chain of custody study.
6. E. Nkonya et al. (eds.) 2016, Economics of Land Degradation and Improvement – A Global Assessment for Sustainable Development, DOI 10.1007/978-3-319-19168-3_1