Forms of soil degradation
Since human activity is the main cause of soil degradation, soil has therefore become a fundamental resource that must be protected. A quarter of cultivated lands are in conditions of increasing degradation with serious risks1
for the continuity of agricultural production.
From the end of the 1940s to the beginning of the 1990s, over 90% of the degradation of productive land was due to agriculture: deforestation2
, inappropriate agricultural practices, irrigation, the spreading of chemical fertilisers and pesticides, overgrazing and even the passage of heavy farming equipment. The degradation process can take different forms:
- hydraulic erosion;
- wind erosion;
- changes in the soil composition;
- physical degradation.
MORE
1
SDG 15 – Life on land: protect, restore and promote sustainable use of terrestrial ecosystems, sustainably manage forests, combat desertification, and halt and reverse land degradation and halt biodiversity loss.
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2
Tropics lost 11.1m hectares of tree cover in 2021. Of the primary rainforest that was lost in 2021, 40% disappeared in Brazil.
Causes of soil erosion
Erosion of soil is a deterioration of land due to the removal of its particles. It consists of three basic stages:
- dislodgement;
- transportation;
- sedimentation.
Their speed depends on the soil type, infiltration, and groundcover.
Topsoil in fields is taken away by strong winds or quick water runoffs during heavy rainfalls. Apart from natural factors, soil erosion may also occur due to irresponsible farm management or deforestation for urban area expansion, tourism development, road construction, and more. Besides, it may be caused by farming itself, when this is managed poorly such as with excessive fertilisation or irrigation, conventional tillage, monocropping, or overgrazing. Agricultural practices can also cause soil erosion due to a reduction of biodiversity both in vegetation variety and soil microorganisms. In their turn, a lack of organic matter and beneficial biota negatively impact field fertility because not only earth particles, but nutrients1 too are taken away from bare fields.
Natural vegetation is a better protection than crops by far because farmlands are more vulnerable to rainfall and winds. Plants, in fact, provide protective cover on the land and prevent soil erosion:
- by slowing down water as it flows over the land (runoff), thus allowing much of the rain to soak into the ground;
- by holding the soil in position thanks to their roots and preventing it from being washed away.
DO
1 Do you know what the process which turns productive land into nonproductive land is called?