2015-12-02. Earth has lost a third of arable land in past 40 years, scientists say.

posted Dec 6, 2015, 2:10 PM by Alan Gould
By Oliver Milman, The Guardian. For GSS Losing Biodiversity chapter 5. Excerpt:  ...New research has calculated that nearly 33% of the world’s adequate or high-quality food-producing land has been lost at a rate that far outstrips the pace of natural processes to replace diminished soil. The University of Sheffield’s Grantham Centre for Sustainable Futures, which undertook the study by analysing various pieces of research published over the past decade, said the loss was “catastrophic” and the trend close to being irretrievable without major changes to agricultural practices. 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. “You think of the dust bowl of the 1930s in North America and then you realise we are moving towards that situation if we don’t do something,” said Duncan Cameron, professor of plant and soil biology at the University of Sheffield. “We are increasing the rate of loss and we are reducing soils to their bare mineral components,” he said. “We are creating soils that aren’t fit for anything except for holding a plant up. The soils are silting up river systems – if you look at the huge brown stain in the ocean where the Amazon deposits soil, you realise how much we are accelerating that process....  http://www.theguardian.com/environment/2015/dec/02/arable-land-soil-food-security-shortage