The Dirt on Our “New” Topsoil

Before we build a house on our land, we will need a septic system.  The land has already passed its perc test (Doesn’t that sound cheerful?  It’s 6 a.m., and at the moment, I’m not sure I feel perky enough to pass any test.)  Our land is not only perky– it even qualifies for an at-grade drain field which is simpler and preferable to a mound system.  But we will still need to cover it with tons of topsoil.

I was leery of trucking topsoil to our land.  Where would it come from?  What would be left of the area from which it was stripped?  Would it arrive redolent of an herbicide-soaked history?

Today I am jumping for joy.  We will be able to get our topsoil from an amazing source – the rich, silty loam in the valley one ridge east of our own.  This topsoil is being removed under the direction of the Nature Conservancy, which is in the process of returning a small section of the head waters of the Pecatonica River to its pristine, pre-settlement state.

That means removing about 30,000 cubic yards of black silt that have migrated down from the surrounding hill tops since the first farmers plowed up the prairie.  The rich soil that was clogging its waters is now being carried to sites nearby, and the last ten truck loads will be coming to our land.

It’s like Christmas in May!  And a small happy ending to a big, sad story.

According to Ken Potter in the Department of Civil and Environmental Engineering at the University of Wisconsin –Madison, Europe settlers were simply not used to the kind of intense thunderstorms that pound North America.  The agricultural traditions they had developed over centuries and brought to their new home made no provisions for the drenching rain that ripped the soil off their new hillside fields.

...Soil erosion is a sadly common story.

By the time they realized what they were dealing with, erosion and destructive flooding had stripped away most of the wealth of topsoil they had found.

The Nature Conservancy site, here in the rugged Driftless Area, has become a collaboration of restoration and study involving soil historians, and environmental researchers who are gathering data about amphibians, water quality, ground water flow and prairie restoration.

“We wanted to do stream restoration,” says Eric Mark from the Wisconsin Nature Conservancy Madison Field Office.  “Taking this area back to what it was before that material was deposited on it has generated a lot of interest.

A section of the Pecatonica, which was once buried in mud and choked with weedy box elder trees now gurgles and sparkles along its original gravel bed.

...Roll down this valley, East Branch of the Upper Pecatonica!

It makes me joyful to think that this rich soil, built and held over eons by the prairie plant community, then mindlessly washed down stream is being moved back up to higher ground. In our case, its new high-ground home is one valley to the west.

Close enough.  From now on it will be lovingly treated like the black gold it is.

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2 replies

  1. OK what is an at-grade drain field, opposed to a mound? In either case is a “tank” still used to store the waste for carting away later? Should I prepare for an outhouse when I next visit??? If this happens in winter I will pre-send a fur seat cover..

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