Top Soil Erosion: An "Under-the-radar" Environment threat

If you thought that Global Warming itself was the worst thing aroung harming the environment – think again! There is one other thing that is harming the liveable environment very clearly specifically in South Asia and no one is quite talking about it! Its the top soil erosion. After population growth, top soil erosion is second biggest factor affecting the Climate.

Annually the earth loses 1% of topsoil mostly due to agriculture. According to the National Academy of Sciences the cropland in the U.S. is being eroded at least 10 times faster than the time it takes for lost soil to be replaced. The situation is even worse in developing and poor countries. In his book “Plan B: Rescuing a Planet Under Stress and a Civilization in Trouble” – Lester R. Brown says:

As soils erode, land productivity falls. An analysis of several studies on the effect of soil erosion on crop yields in the United States concluded that for each 1 inch of topsoil lost, wheat and corn yields declined by 6 percent. A 1982 USDA Natural Resource Inventory, which measured the loss of topsoil from U.S. cropland at 3.1 billion tons per year, found that excess erosion was concentrated on a small share of the land. It set the stage for the landmark 1985 Conservation Reserve Program.9

Ethiopia, a mountainous country with highly erodible soils on steeply sloping land, is losing an estimated 1 billion tons of topsoil a year. This is one reason why Ethiopia always seems to be on the verge of famine, never able to accumulate enough grain reserves to provide a meaningful measure of food security.

India is thought to be losing 4.7 billion tons of topsoil a year, mostly through water erosion. Its monsoonal climate, with the concentration of rainfall during a few months of the year, leaves its exposed soils vulnerable to erosion.

In neighboring Nepal, a government report estimated annual soil nutrient loss from erosion at 1.3 million tons—on top of the 500,000 tons of soil nutrients removed through harvesting of crops. Of this total loss of 1.8 million tons, only 300,000 tons are being replaced through the use of organic and mineral fertilizers.

A Cornell study in 2006 reported some alarming numbers:

Around the world, soil is being swept and washed away 10 to 40 times faster than it is being replenished, destroying cropland the size of Indiana every year

Here are some more statistics from that study that will surely alarm you:

The vast majority — 99.7 percent — of human food comes from cropland, which is shrinking by more than 10 million hectares (almost 37,000 square miles) a year due to soil erosion, Pimentel reports, while more people than ever — more than 3.7 billion people — are malnourished.

“Erosion is one of those problems that nickels and dimes you to death: One rainstorm can wash away 1 mm (.04 inches) of dirt. It doesn’t sound like much, but when you consider a hectare (2.5 acres), it would take 13 tons of topsoil — or 20 years if left to natural processes — to replace that loss,” Pimentel said. “And that kind of loss occurs year after year by wind and rain around the world.”

The study, which pulls together statistics on soil erosion from more than 125 sources, reports:

– The United States is losing soil 10 times faster — and China and India are losing soil 30 to 40 times faster — than the natural replenishment rate.
– The economic impact of soil erosion in the United States costs the nation about $37.6 billion each year in productivity losses. Damage from soil erosion worldwide is estimated to be $400 billion per year.
– As a result of erosion over the past 40 years, 30 percent of the world’s arable land has become unproductive.
– About 60 percent of soil that is washed away ends up in rivers, streams and lakes, making waterways more prone to flooding and to contamination from soil’s fertilizers and pesticides.
– Soil erosion also reduces the ability of soil to store water and support plant growth, thereby reducing its ability to support biodiversity.
– Erosion promotes critical losses of water, nutrients, soil organic matter and soil biota, harming forests, rangeland and natural ecosystems.
– Erosion increases the amount of dust carried by wind, which not only acts as an abrasive and air pollutant but also carries about 20 human infectious disease organisms, including anthrax and tuberculosis.

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