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 blame—research 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 State University 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.