Soil erosion commonly appears after conversion of forests to agricultural land, sweeping away fertile soil, pesticides and the sources of liveliood for humans and wildlife.
Forest conversion and soil erosion
Soil erosion in Madagascar
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More calamities after the forests are gone
Damage to areas that are cleared of forests and replaced with plantations continues long after the trees are gone.
Erosion is also accentuated by planting trees in rows up and down hillsides rather than on contours around them, and by poorly planned infrastructure such as roads.
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 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.
What is erosion?
When forests are cleared, the exposed topsoil often begins to erode, increasing sedimentation into watercourses (e.g. rivers). The situation worsens if there are no forests left along the banks of rivers to hold soil carried by rain. Coffee, cassava, cotton, corn, palm oil, rice, sorghum, soybean, tea, tobacco, and wheat are some of the crops whose cultivation cause soil erosionDuring soy production, lack of soil cover and exposure to the wind causes erosion and infertile soils. As a result, every year, Brazil loses 55 million tonnes of topsoil.
What is the scale of the erosion problem?
It is estimated that since 1960, one-third of the world’s arable land has been lost through erosion and other degradations. 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 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.
Erosion is a result of deforestation. Ivohibe, Madagascar
From savanna to desert: a ‘how-to’ guide
Urbanisation and erosion in the Cerrado, Brazil.
In the Brazilian Cerrado, the combined effects of deforestation and increased soil temperatures have made it difficult for rainwater to sink into the soil.
When plantation areas of up to 10,000 hectares are exposed following deforestation, the soil becomes extremely vulnerable to wind and water erosion. As a result, desertification has become a serious threat to these areas, which experience a long dry season.
In the Santarem region, intensive rainfall causes erosion, especially near streams and rivers. The sediment is transported downstream, where it makes the rivers and coves turbid.
