A Farmer and His Super Soil

The following is an excerpt from Rancher, Farmer, Fisherman: Conservation Heroes of the American Heartland, by Miriam Horn.

A first lesson Kansas farmer Justin Knopf learned from the prairie is the importance of physical protection: keeping a roof of living and dead plants over the soil and its inhabitants. Walking into the tall, stout, crunchy stubble of a cornfield, Justin lifts an edge of the thick, dense carpet of “residues” he left behind when he harvested here a few weeks earlier: a tatami mat of yellowing leaves, stripped cobs and year-old wheat straw. “If we have heavy rain, that raindrop is going to land on this residue instead of on bare soil. It could blow or rain like mad and nothing will leave this field.” The mat also protects everything living in the field, beginning with the crop itself. Justin doesn’t grow much corn, which pollinates and needs lots of water and cool temperatures in just those months when Kansas is blistering under the hot sun. But when he does, having this “natural mulch of wheat residue between rows really helps reduce evaporation and cool the soils.” It also suppresses weeds, giving the crop a head start.

Above ground, the stubble provides shelter for grassland birds, a highly vulnerable group in fast decline as ever more of their habitat is converted to farms. Justin often hears the low, fussy clucking of ring-necked pheasants in his fields, startles up a family of bobbling quail, or pauses to watch a coyote skulk about in search of fledglings or eggs. In Illinois, researchers have found that no-till fields host significantly more and diverse nesting birds, including threatened upland sandpipers, Eastern meadowlarks and field sparrows.

Leaving the dead remnants of the previous crop atop the soil also protects the life underground, not only keeping the microbial hordes cool and moist but also—the second lesson of the prairie—feeding them at a more temperate pace. “See how everything is gradually crumpling as the fungi eat it,” asks Justin, “from the bottom up? We’ll find pieces of milo stalk three years later. My grandfather was taught that by plowing under the residue they were feeding it back to the soil. They didn’t realize the soil could feed it back to itself, at a slower pace that’s much better for the soil.” Turned under, Kansas State soil microbiologist Dr. Rice explains, all that leftover plant material overstimulates the microbes, “like giving sugar to a kid.” Fast-growing bacteria explode, eating their way through the organic material and exhaling much of it into the air. A slow-food diet, by contrast, nurtures more efficient fungi that store most of what they eat in their own growing bodies, keeping it there (and thus in the soil) even after they die. Their long, weblike hyphae also perform services for Justin’s crops: bringing the plants nutrients they can’t reach on their own and binding the soil in the big, soft lumps roots love.

Rancher, Farmer, Fisherman: Conservation Heroes of the American Heartland

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Over time, the proper care and feeding of soil fauna rebuilds the organic matter that is essential to crop health. Most soils are made up largely of minerals—weathered from rock and deposited by the wind (loess), by flood (alluvium), or at the base of hills and mountains (colluvium). Some of those minerals are like tiny electric snowflakes, grabbing with their negatively charged points and edges onto nutrients—like calcium and potassium—which are mostly positively charged, so “a root can get in like a big straw and suck them up,” as UC Berkeley biogeochemist Whendee Silver explains. That’s good, but organic matter is better: not crystals but amorphous, rotting goo, the “bits of slime” Justin loves to find in his soils. That goo coats soil particles, says Silver, “jamming in lots of charges” and therefore grabbing and holding onto lots more nutrients, making the soil both more fertile and less “leaky.” Its stickiness also helps glue together the desirable “aggregates” that hold water and resist erosion. “Drop a chunk of healthy soil with good structure into water,” says Justin, “and it will hold together and float around. Try the same thing with overworked soil, and the water will turn cloudy as the soil dissolves.”

Farming in concert with the prairie requires constant, close, almost paternal attention: Justin knows the land intimately through soil testing and data analysis but even more through his own senses and hands. In an essay she wrote for an online writing class, Lindsey describes watching Justin “studying, seeing things I can’t see . . . turn[ing] the wheat over in his hands, examining every square inch with the eye of a scientist and the touch of a father. His nail scrapes away at something, his nose almost touching the wheat.”

Justin is as often striding across a field as he is cocooned in a tractor: opening a furry soybean pod to bite into one of the tiny egg-yolk-yellow seeds to see if it’s ready to harvest, stopping to dig with the small shovel he carries everywhere, or crouching to sink his big hands deep into the black, fragrant soil. He is often joined by his young employee Garrett, a bright young K-State graduate who reminds Justin of himself fresh out of college—though Garrett is so skinny the shovel barely notices him when he jumps on. Sometimes Andrew comes along too, with his own pint-sized shovel, diligently digging alongside his dad. It would be hard to say who is more excited by their discoveries, especially the fat earthworms whose excavations and excretions inspire in Justin a thrill and awe so fervent as to verge on comical. Even a pile of their castings brings him joy. “Oh this is wonderful. This shiny material is their poop, or ‘frass,’ very rich for plants. They burrow down five feet or more, eating all the time, filling their bellies with nutrients that they carry from deep in the soil up to the root zone, and carrying other things back down. In deep drought they go deeper still, tie themselves in a knot and go dormant. We can’t see fungi or bacteria, so earthworm activity is my best measure of biological activity. What a gift this is.”

Excerpted from Rancher, Farmer, Fisherman: Conservation Heroes of the American Heartland by Miriam Horn. Copyright © 2016 by Miriam Horn. Used with permission of the publisher, W.W. Norton & Company, Inc. All rights reserved.