Milman, O. December 2, 2015. Earth has lost a third of arable land in past 40 years, scientists say. The Guardian.
The world has lost a third of its arable land due to erosion or pollution in the past 40 years, with potentially disastrous consequences as global demand for food soars. 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 continual plowing 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 1 inch (2.5 cm) of topsoil to be created amid unimpeded ecological changes.
The University of Sheffield’s Grantham Centre for Sustainable Futures, which undertook the study by analyzing 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. “You think of the dust bowl of the 1930s in North America and then you realize 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 realize how much we are accelerating that process.
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.
The steep decline in soil has occurred at a time when the world’s demand for food is rapidly increasing. It’s estimated the world will need to grow 50% more food by 2050 to feed an anticipated population of 9 billion people. [Yet already, much of the world’s land is already being used to grow food]…Around 30% of the world’s ice-free surfaces are used to keep chicken, cattle, pigs and other livestock, rather than to grow crops.
Read a summary of the paper here as well: Grantham Centre briefing note: December 2015 A sustainable model for intensive agriculture