Good health starts with good soil, and ours has seen better days. Part one of a two-part dispatch on the sorry state of our nation’s soil and what we can do to fix it. Read part two here: “Bringing Life Back to Soil.”
The past 12 months have been hard
on the soil in farm country. There was the great drought of 2012, followed by
the great dampening of 2013. First it blew away–“I have not witnessed
such a widespread area of wind erosion,” one veteran soil expert told me
when describing storms in the southern part of Minnesota last year. Now it’s washing off
the land–“The rivers around here are running brown,” a farmer told
me earlier this summer.
Volatile weather is partially to
out of Iowa shows violent rainstorms are producing gully erosion rates 12
times higher that originally thought. But stories of extreme erosion events,
while striking, threaten to overshadow the everyday situation literally right
beneath our feet. People close to the land are starting to notice what’s
happening to our soil when it’s NOT parched or saturated. During the past half-dozen
years, I’ve talked to farmers, scientists and natural resource professionals
from around the country who are saying generally the same thing: it doesn’t
take much to send soil flowing or flying these days, no matter the conditions.
While driving through southeast Minnesota
in early July, I was struck at how even relatively flat fields were laced with
rivulets of rill erosion.
We have made impressive strides in
conservation since the Dust Bowl days. No-till systems, grassed waterways,
terracing and retirement initiatives like the Conservation Reserve Program
reduced erosion levels by roughly 30 percent from 1982 to 2007 alone, according
to the USDA. But those official numbers have not been updated since 2007,
and a lot has happened in six years.
Soil scientists and farmers now say
we are increasingly “exceeding the capacity” of traditional conservation
methods. In other words, it’s not enough anymore to just put in a terrace to
keep soil from sliding down a hill. “The net effect is, we are going
backward on soil conservation,” Iowa
soil scientist Richard Cruse told me recently.
Part of the reason is that more
land is being plowed up as a result of high prices for commodities like corn
and a government subsidized
insurance program that provides a perverse incentive to till land normally
considered too marginal for cropping. Between 2006 and 2011, 1.3 million acres
of grassland was converted to crops in Minnesota,
Iowa, North Dakota,
South Dakota and Nebraska, according to the Proceedings
of the National Academy of Sciences. We haven’t seen such conversion rates
since the 1930s.
But perhaps a more insidious threat
to our ability to produce food while keeping sediment–and all the contaminants
along for the ride–out of our water lies in topsoil, our agronomic basement,
where bugs, bacteria and decomposing plants interact to cook up organic matter.
Organic matter makes up a tiny fraction of our soil, but controls everything
from plant nutrition and how much carbon soil can sequester to its ability to
soak up rain. Organic matter makes “dirt” into productive “soil.”
As agriculture transformed into a
less diverse, mono-cropped system, organic matter levels plummeted. Unbroken
prairie soils have as much as 10 percent or more organic matter, but over the
years levels in Midwestern crop fields have in some cases dropped to below 2 percent
of total topsoil volume.
Over 46 percent of the world’s soil
is experiencing significantly “destroyed” biological functions,
according to the International
Soil Reference and Information Centre. In some cases soil is so compacted
and lifeless that roots can’t penetrate easily; soil compaction costs
Midwestern farmers some $100 million a year through lost productivity. The
bottom line: our soil is too sick to function properly.
Brian DeVore works for the Land Stewardship Project, a nonprofit organization fostering sustainable agriculture since 1982. DeVore writes for and edits the group’s publication, The Land Stewardship Letter.
Image: In mid-October, 2012, strong winds ripped through the northern plains, with sustained winds across South Dakota of 30 to 50 mph. Photo by USDA NRCS South Dakota, licensed under Creative Commons.