Earth has lost a third of arable land in past 40 years, scientists say
▻http://www.theguardian.com/environment/2015/dec/02/arable-land-soil-food-security-shortage
The continual ploughing of fields, combined with heavy use of fertilizers, has degraded soils across the world, the research found, with erosion occurring at a pace of up to 100 times greater than the rate of soil formation. It takes around 500 years for just 2.5cm of topsoil to be created amid unimpeded ecological changes.
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The erosion of soil has largely occurred due to the loss of structure by continual disturbance for crop planting and harvesting. If soil is repeatedly turned over, it is exposed to oxygen and its carbon is released into the atmosphere, causing it to fail to bind as effectively. This loss of integrity impacts soil’s ability to store water, which neutralizes its role as a buffer to floods and a fruitful base for plants.
Degraded soils are also vulnerable to being washed away by weather events fueled by global warming. Deforestation, which removes trees that help knit landscapes together, is also detrimental to soil health.
