Healthy soil and sustainable growing

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The lowdown on topsoil: It's disappearing
http://seattlepi.nwsource.com/local/348200_dirt22.html

Disappearing dirt rivals global warming as an environmental threat

Tuesday, January 22, 2008
By TOM PAULSON
P-I REPORTER

The planet is getting skinned.

While many worry about the potential consequences of atmospheric warming, a
few experts are trying to call attention to another global crisis quietly
taking place under our feet.

Call it the thin brown line. Dirt. On average, the planet is covered with
little more than 3 feet of topsoil -- the shallow skin of nutrient-rich
matter that sustains most of our food and appears to play a critical role
in supporting life on Earth.

"We're losing more and more of it every day," said David Montgomery, a
geologist at the University of Washington. "The estimate is that we are now
losing about 1 percent of our topsoil every year to erosion, most of this
caused by agriculture."

"It's just crazy," fumed John Aeschliman, a fifth-generation farmer who
grows wheat and other grains on the Palouse near the tiny town of Almota,
just west of Pullman.

"We're tearing up the soil and watching tons of it wash away every year,"
Aeschliman said. He's one of a growing number of farmers trying to persuade
others to adopt "no-till" methods, which involve not tilling the land
between plantings, leaving crop stubble to reduce erosion and planting new
seeds between the stubble rows.

Montgomery has written a popular book, "Dirt," to call public attention to
what he believes is a neglected environmental catastrophe. A
geomorphologist who studies how landscapes form, Montgomery describes
modern agricultural practices as "soil mining" to emphasize that we are
rapidly outstripping the Earth's natural rate of restoring topsoil.

"Globally, it's clear we are eroding soils at a rate much faster than they
can form," said John Reganold, a soils scientist at Washington State
University. "It's hard to get people to pay much attention to this because,
frankly, most of us take soil for granted."

The National Academy of Sciences has determined that 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 United Nations has warned of worldwide soil degradation -- especially
in sub-Saharan Africa, where soil loss has contributed to the rapidly
increasing number of malnourished people.

Healthy topsoil is a biological matrix, a housing complex for an incredibly
diverse community of organisms -- billions of beneficial microbes per
handful, nitrogen-fixing fungi, nutrients and earthworms whose digestive
tracts transform the fine grains of sterile rock and plant detritus into
the fertile excrement that gave rise to the word itself ("drit," in Old
Norse).

As such, true living topsoil cannot be made overnight, Montgomery
emphasized. Topsoil grows back at a rate of an inch or two over hundreds of
years. Very slowly.

"Globally, it's pretty clear we're running out of dirt," Montgomery said.

Ron Myhrum, state soil scientist with the U.S. Department of Agriculture's
office in Spokane, agreed that global soil loss is a huge problem. But
Myhrum said erosion rates in the Northwest region have improved recently
because of better conservation farming practices, including federal
payments to farmers to leave some natural ground cover in highly erodible
areas.

"We don't have the kind of dust storms here we used to have," Myhrum said.
"What's more alarming to me than erosion is conversion of farmland to urban
use."

That is indeed another way to lose soil -- paving it over. Judy Herring,
manager of King County's farmland preservation program, said the county has
lost 60 percent of its farmland since the 1960s. In 1979, Herring said,
voters approved a bond program that buys back farmland to protect it from
development (and has done this for 13,200 acres so far).

But while some land is lost to development, pollution or changing weather
patterns, Montgomery, Reganold and others say global soil loss is a crisis
mostly rooted in agriculture.

"Erosion rates have improved here, but that doesn't mean they're good,"
Reganold said. Topsoil clearly is still being stripped off faster than it
can be regenerated, he said.

Aeschliman, the Palouse farmer, a stocky and energetic man who doesn't seem
to notice that he's in his 60s, stood on a dirt road looking at the
difference between his land and that of a neighbor. Because most neighbors
are relatives, he did not provide any names here.

"Just look at that!" he bellowed, pointing to a series of water-carved
cracks and gouges running down a recently tilled field of wheat. Every
year, he said, these fields are tilled and the rains come, washing the soil
down into the road so deep the county routinely has to dig it out. The rest
of the soil runs off to the Snake River and, eventually, to the Pacific.

"Here, look at this stuff," Aeschliman said as he held up a handful of the
fine brown silt that had eroded off his neighbor's (cousin's) hillside.
"Now, look over here."

He walked across the road to his no-till wheat field. Unlike the rolling
hills of loose dirt on the tilled field, Aeschliman's field looks more like
a shag rug, with its rows of dead wheat stubble. He reached down into the
dirt and pulled out a coarsely textured, much darker clump of dirt, roots
and debris.

"This soil is full of worms, bacteria and all sorts of life," Aeschliman
said. "And it stays put. That stuff over there (waving his thick hand back
behind him) is just powder, brown dust. It's dead. There's no worms, no
life in it."

Thirty years ago, Aeschliman was one of the first in the Palouse to grow
his grains using no-till farming methods. He's an ardent no-till
proselytizer today, but he didn't abandon tilling the fields based on some
organic epiphany or desire to save the world.

"I just got tired of all the mud," Aeschliman said. The family home, built
in the 1880s, sits at the base of a long drainage off the rolling wheat
fields. Every spring, with the tilling and the rain, his home would be a
foot deep in muddy runoff.

No-till farming could do a lot to reduce topsoil erosion, Reganold said,
but it's not without its downsides. Switching to no-till farming requires
heavy upfront investment and learning new techniques, he said, and also
tends to depend more on herbicides because the weeds are no longer
controllable by plowing them into the soil.

Organic farming methods also can reduce soil loss, Reganold said. He cited
his own research, which has shown a marked increase in soil health, water
retention and regrowth when organic methods are used rather than the
traditional methods.

A regional association of farmers and other proponents of no-till
agriculture, also known as direct-seed farming, is holding its annual
meeting in Kennewick next week. Aeschliman is one of the founders of the
organization, the Pacific Northwest Direct Seed Association, and is happy
to see that no-till farming is growing in popularity.

"It's both good for the soil and good for your pocketbook," he said.

P-I reporter Tom Paulson can be reached at 206-448-8318 or
tompaulson-at-seattlepi.com.

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