Signs of collapse: topsoil erosion

[ Although I wrote about a lot of issues in 2007 when I published Peak Soil, these articles have more recent statistics.

Alice Friedemann   www.energyskeptic.com  author of “When Trucks Stop Running: Energy and the Future of Transportation”, 2015, Springer and “Crunch! Whole Grain Artisan Chips and Crackers”. Podcasts: Derrick Jensen, Practical Prepping, KunstlerCast 253, KunstlerCast278, Peak Prosperity , XX2 report ]

Jonathan Watts. September 12, 2017. Third of Earth’s soil is acutely degraded due to agriculture. Fertile soil is being lost at rate of 24bn tonnes a year through intensive farming as demand for food increases, says UN-backed study. The Guardian.

The alarming decline, which is forecast to continue as demand for food and productive land increases, will add to the risks of conflicts such as those seen in Sudan and Chad.

“As the ready supply of healthy and productive land dries up and the population grows, competition is intensifying for land within countries and globally,” said Monique Barbut, executive secretary of the UN Convention to Combat Desertification (UNCCD) at the launch of the Global Land Outlook.

The Global Land Outlook is billed as the most comprehensive study of its type, mapping the interlinked impacts of urbanisation, climate change, erosion and forest loss. But the biggest factor is the expansion of industrial farming.

Heavy tilling, multiple harvests and abundant use of agrochemicals have increased yields at the expense of long-term sustainability. In the past 20 years, agricultural production has increased 3-fold and the amount of irrigated land has doubled.  Over time this diminishes fertility and can ultimately lead to desertification.

Decreasing productivity can be observed on 20% of the world’s cropland, 16% of forest land, 19% of grassland, and 27% of range land.

Industrial agriculture is good at feeding populations but it is not sustainable. It’s an extractive industry [of topsoil which takes 500 years to be geologically replenished].

Worst affected is sub-Saharan Africa, but poor land management in Europe also accounts for an estimated 970m tonnes of soil loss from erosion each year with impacts not just on food production but biodiversity, carbon loss and disaster resilience.

 

George Monbiot. March 25, 2015. We’re treating soil like dirt. It’s a fatal mistake, as our lives depend on it. War, pestilence, even climate change, are trifles by comparison. Destroy the soil and we all starve. The Guardian.

Landowners around the world are now engaged in an orgy of soil destruction so intense that, according to the UN’s Food and Agriculture Organisation, the world on average has just 60 more years of growing crops. Even in Britain, which is spared the tropical downpours that so quickly strip exposed soil from the land, Farmers Weekly reports, we have “only 100 harvests left”.

To keep up with global food demand, the UN estimates, 6m hectares (14.8m acres) of new farmland will be needed every year. Instead, 12m hectares a year are lost through soil degradation. We wreck it, then move on, trashing rainforests and other precious habitats as we go.

The techniques that were supposed to feed the world threaten us with starvation. A paper just published in the journal Anthropocene analyses the undisturbed sediments in an 11th-century French lake. It reveals that the intensification of farming over the past century has increased the rate of soil erosion 60-fold.

Another paper, by researchers in the UK, shows that soil in allotments – the small patches in towns and cities that people cultivate by hand – contains a third more organic carbon than agricultural soil and 25% more nitrogen. This is one of the reasons why allotment holders produce between four and 11 times more food per hectare than do farmers.

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

 

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