The Joplin Globe, Joplin, MO

Farm

Discussion

July 9, 2007

Inch of topsoil needs 500 years

It takes little time to waste it

By Mike Surbrugg

msurbrugg@joplinglobe.com

500 years.

That’s how long it takes the earth to form an inch of topsoil, according to the U.S. Department of Agriculture’s Natural Resources Conservation Service.

The timeline for the latest inch of topsoil began in 1507 — about the time that Michaelangelo was working on the Sistine Chapel.

Ben Reed, conservationist with the Barton County Soil and Water Conservation District in Lamar, has spoken at elementary schools and at meetings about the importance of protecting topsoil.

He used an apple recently to illustrate his point about the importance of topsoil. Since nearly 75 percent of the earth is covered by water, he cut off 75 percent of the apple. Included in what’s left is the Arctic and Antarctica and other areas where people do not live, or about 10 percent of the apple. Another 10 percent of the apple was removed to represent areas not suited for crop production.

Reed ended up holding a sliver of the apple that represents the 5 percent of the earth suited for growing food.

Then he carefully cut away the peeling, which represents the topsoil where plants can grow.

“That six to eight inches of topsoil depth is all that stands between us and extinction,” he said.

While it takes 500 years to build an inch of topsoil, it certainly does not take that long to waste an inch of topsoil.

Prior to no-tillage farming, contour farming, making better use of forages and other conservation steps, the amount of soil lost by erosion in Missouri in a year would create a pile 70 feet high in each of four lanes of Interstate 70 between Kansas City and St. Louis.

That pile has been lowered to 20 feet deep along those four lanes, he said.

Topsoil also is lost during flooding and ends up in lakes and rivers where it changes from a life-supporting element into pollution.

Details and ways to save topsoil are available at any county Soil and Water Conservation district or from any Natural Resources Conservation Service office.

Mike Surbrugg is The Joplin Globe’s farm editor.

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