Carbon Trading: Nature’s Version
Soil may be considered as the conversion of rock by two processes. One is a process of aging, the other is a process of living.
—P. A. Yeomans3
Carbon trading is something that has been going on for millennia in our soils. It underpins the health of our whole ecosystem.
—Christine Jones
ANY EARNEST DISCUSSION OF SOIL CARBON will inevitably wend its way to Australian soil scientist Christine Jones. Over the last eight to ten years, Jones’s articles and posts on her website—www.amazingcarbon.com— have become foundational documents for those, like Peter and Abe, who seek to rein in carbon dioxide levels by working in tandem with ecological cycles. Her determination to promote soil restoration as an engine for environmental renewal is matched only by her frustration that the powers-that-be seem set on ignoring her message.
In Australia, as in the United States, the conventional belief is that what determines the crop-worthiness of a patch of land is its “nutrient status,” the levels of the macronutrients nitrogen, potassium, and phosphorus. These can be bumped up via synthetic and organic fertilizers. For Jones, it’s all about soil carbon, which needs to be built by biological processes and is hindered by the very amendments purported to guarantee bumper yields. She’s taken this message on the road, talking to farmers, gardeners, and politicians willing to listen, attending field days and giving workshops across Australia and abroad, telling it straight. Her presentation aids tend toward the earthy: yellow buckets, a tape measure, tufts of grass weighed down with soil and roots.
A forthright woman in her late fifties who looks most comfortable out in the field under a tan, broad-rimmed Akubra hat, Jones has had her share of dustups with the agricultural and academic establishments. There was, for example, “the great salinity debate” of the early 2000s, over how to address high salt levels that were undermining farmland productivity in much of the country. To national farming and environmental groups, the answer was to plant lots of native trees. According to Jones, though, prior to European settlement the bulk of the continent was grassy woodland rather than actual forest, and dryland salinity signaled problems with the soil, specifically a lack of soil organic matter. She’s proposed and launched several carbon sequestration programs, only to hit the inevitable bureaucratic wall. Yet she has helped bring soil carbon into national parlance in Australia—something that’s yet to happen anywhere else.
When asked about her early background, the phrase Jones offers is paradise lost. In part, she means this on a personal level. She describes an idyllic childhood among loving family in a sleepy fishing village on New South Wales’s picturesque South Coast, living in a tiny log cabin graced by broad, leafy tree ferns. “We were largely self-sufficient,” she recalls. “I have fond memories of going fishing with Dad, helping Mum make jam, tending ‘my garden’ (Dad had given me a section of my own), walking to the dairy across the road for our daily billy of fresh warm milk, dipping my fingers into the thick layer of delicious cream on the homeward trip. Much to my mother’s dismay I had a great fascination for frogs, lizards, spiders, and snakes, which I kept in special places in the garden.” When she was ten years old the family uprooted and moved to Sydney. Life in the city was not her style: “It was an alien world beyond my comprehension.”
Jones refers also to the loss of Australia’s paradisiacal wildness, much of which she’s witnessed in her lifetime. The lush, fertile countryside, filled with fabulous creatures (fabulous at least to the nonphobic and unsqueamish), has been tamed, engineered, and exploited, as much of Australia’s land has been overgrazed, paved over, or had the life farmed out of it. When Europeans first settled in the early 1800s, the soil was described as peaty, crumbly, and soft—so soft that horses were prone to stumble and occasionally broke their legs. Trouble was, the loamy veneer was thin and the climate hot and dry. Yet the colonials went at the land with their plows and tills as if they were still in moist, temperate Europe. The introduction of foxes and rabbits, which killed and out-competed native species like dunnarts (a small marsupial related to the Tasmanian devil) and the spotted quoll (another marsupial), didn’t help.
Today Australian land is largely arid, acid, and saline. In October 2011, Rolling Stone ran a cover story on “the end of Australia,” a nightmarish piece that portrayed the country’s struggle with heat, droughts, fires and floods, dying reefs, and parched riverbeds as a harbinger of the ravages that climate change has in store for the rest of the world. While many in Oz would dispute one countryman’s characterization of their homeland as “the petri dish of climate change,” most would acknowledge the island nation’s ecological fragility. Upward of 70 percent of Australia’s land is considered degraded. The country has the highest carbon emissions per capita of any in the world.
Jones went on scholarship to the University of New South Wales, graduating with First-Class Honours with a major in wool and pastoral sciences. While a degree in wool science might sound like the punch line of some Aussie joke (just add a reference to beer, convicts, kangaroos, and a “G’day, mate!” or two), keep in mind that wool was long a core national industry; it’s said that Australia was “built on the sheep’s back.” Jones’s subsequent work as a textile technologist is what prompted her interest in soil. She explains that there are “several processes involved in turning raw wool into yarn. First, the wool is scoured, or washed, then carded and combed into tops, which are like coils of rope. The wool tops are then spun into yarn. If wool fibers are uneven in thickness along their length, they break at the narrowest point. This can result in a great deal of wastage during the top-making process and can also reduce the ‘spinnability’ of the yarn. Variations in the thickness of wool fibers are mainly due to changes in the quality and quantity of pasture throughout the year. To cut a long story short, my interest in wool became an interest in pastures, which became an interest in soil, which ultimately became an interest in the question, ‘what makes soil tick?’”
Jones went back to the university for a PhD, exploring the biochemistry of the plant–soil relationship. She says: “I quickly realized that plants are anything but ‘passive’ and soils are anything but ‘inert.’ There is this extraordinary world beneath our feet, fueled by energy from the sun, of which we are largely unaware. For me, this realization was like the lifting of a heavy fog. It suddenly became clear that within the soil lay answers to myriad so-called problems.”
Not only in the wool industry, but other agricultural sectors. And over time Jones came to believe plant–soil dynamics provided answers to larger environmental concerns, among them our surfeit of green-house gases and the daunting challenge of growing food for a seven-billion-and-counting world. The question that’s continued to haunt her, from her stints in the business world and the Commonwealth Scientific and Industrial Research Organisation (CSIRO), Australia’s main research agency, to her current role as independent scientist, has been: How can she draw the needed attention to soil health when there are entire industries and institutional hierarchies set up to peddle Band-Aid solutions while perpetuating the underlying problems?
Christine Jones is the type of thinker who speaks to the gaps between chapters in a textbook, concepts not covered on the test. Fortunately, she has a vivid way of explaining these ideas, with a touch of the clarifying metaphor. For instance, she looks at the mechanisms of photosynthesis from the standpoint of soil carbon, making the connection between what happens on the leaf and what happens in the ground. Here we move from Peter Donovan’s near-cosmic atmospheric scenarios to the nitty-gritty of the mundane workings of a clump of soil. We all dutifully read our high school science textbooks so we know that through some miraculous alchemy, the chlorophyll that speckles a plant’s leaves is able to transform air and sunlight into energy the plant can use. Then what happens? The plant grows. The plant energy becomes food for us and for other creatures, large and small. In time, the plant dies and the remnants of that plant energy biodegrade and return to the soil as organic matter. What Jones says is that there’s another process going on, one with important implications for sequestering carbon and building topsoil, and doing so rapidly—thus hitting two angles of our carbon problem. She calls it “the liquid carbon pathway.”
To understand this evocative phrase, we need to slightly revise our conceptualization of a plant. Rather than a mostly green thing embedded in the ground that pulls water and nutrients from the soil, Jones would have us think of a two-way pump. The upward flow is water, minerals, and other substances the plant needs; the downward flow is soluble carbon (dissolved organic carbon) that seeps into and out through the plant’s roots so as to feed other organisms in the soil. This downward carbon flow stimulates the production of humus, the organic component of soil that is a repository for carbon as well as the basis for fertility. The more carbon in the soil, the more energetic the microbes; the more energetic the microbes, the more mineral particles are broken down; the more minerals are broken down and made available to plants, the more humus. “We have the idea that plants take from the soil,” says Jones. “Nothing can be farther from the truth.”
We know that through the process of decay, plant material humifies and becomes a stable, carbon-rich component of soil; it’s not prone to chemical or physical breakdown and, if undisturbed, can remain in this form for centuries, even millennia. Jones is saying that the living plant also creates humus, serving as a conduit for the energy that drives its production. In doing so the plant is delivering the sun’s energy underground, where it is stored as living soil. In Jones’s words, the soil “behaves like a battery, fueling the above-ground ecosystem from the soil up as well as from the sun down.” The soil, then, serves as a storehouse for latent energy—in the form of humus—pulled down from the sun.
As Jones recognized when she was a young scientist, soil is far from inert. At any given moment there’s much ferrying of food and energy going on beneath our feet—an intricate system of reciprocal and contingent exchanges, the complexity of which would put those geniuses who invented stock derivatives to shame. For our purposes, let’s keep things simple and focus on how the liquid carbon pathway makes its way to one particular life-form essential to the fixing of carbon in the soil (and, not coincidentally, Christine Jones’s favorite biota), mycorrhizal fungi.
These are fungi that forge symbiotic associations with the roots of plants. Under natural conditions, upward of 80 percent of plants that flower have cooperative links with mycorrhizal fungi. This includes grasses—though, curiously, not brassica, the vegetable family of broccoli, kale, cabbage, and the like. Mycorrhizal fungi have long, threadlike filaments called hyphae that carve paths into the soil, extending the “reach” of a plant and increasing its access to nutrients and water. These hyphae can attain impressive lengths: A teaspoon of soil in the vicinity of a robust plant might hold strands that, when stretched end to end, would span nearly half a mile. According to one study, the hyphae found in the top four inches of forty-three square feet of healthy grassland would run the length of the equator.
A key function of mycorrhizal fungi (the name means “root fungus”) is governing the nutrient give-and-take between plants and soil, acting as a trading center for subterranean biochemical barter. The mycorrhizal fungi “provide essential nutrients to plants in exchange for liquid carbon,” says Jones. “They cannot utilize any other form of energy other than dissolved organic carbon that has been provided by a living plant. In the absence of plant roots, you cannot grow mycorrhizal fungi in a laboratory.” They also enhance a plant’s resistance to disease, drought, and difficult soil conditions like acidity or salinity. Jones likens the long, stringy hyphae, full of sugar they’ve taken from the plant, to “fairy floss” (that’s Australian for “cotton candy”).
The liquid carbon the plant discharges into the soil via its mycorrhizal fungal partners also feeds other microbes that, in turn, supply minerals to plants in a soluble form they can use. Plants happy, microbes happy, soil lavished with minerals and organic matter. A plant with mycorrhizal connections can transfer up to fifteen times more carbon to soil than a non-mycorrhizal counterpart.
There’s another aspect to these root fungi scientists are still learning about: glomalin, a sticky secretion—it’s been called “soil’s superglue”— that coats the spindly hyphae. This glycoprotein (both a carbohydrate and a protein) was only discovered in 1996 by Sara F. Wright, a soil scientist with the USDA’s Agricultural Research Service (ARS). Glomalin is significant for two reasons: It holds carbon, storing it for as long as several decades (a study by microbiologist Kristine A. Nichols of the ARS determined that glomalin represents on average 15 percent of carbon in soils); and it binds soil particles to create aggregates, which lends soil its tilth—that soft, granular quality you get when you run a handful of good soil through your fingers. This helps keep soil stable and resistant to erosion while allowing for air and water flow. As one USDA brochure asks rhetorically, “Does glomalin hold our farm together?”
Kristine Nichols, who works out of the ARS’s Northern Great Plains Research Laboratory in Mandan, North Dakota, says this is not hyperbole: Glomalin may be central to soil formation. The “stickiness” of glomalin—like “little gobs of chewing gum,” she says—binds together particles of sand, silt, and clay and plant and other organic debris to form aggregates within the “string bag” of the stringlike hyphae. The glomalin then forms a “latticelike waxy coating” that keeps the aggregate intact and protected and ensures that water and nutrients are available to the associated plant.
“Soil structure is the 3D structure of open and closed spaces,” Nichols explained in an email. “If the closed spaces are formed by soil aggregates rather than individual soil particles, the open space between these aggregates will be larger, which will allow for better water and gas movement along with reducing compaction.”
In other research, Nichols found more glomalin in prairies marked by native plants as compared with non-native plants, reflecting the interdependence that has evolved among indigenous grasses and mycorrhizal fungi.
Mycorrhizal affiliations benefit a plant in terms of growth, resistance to drought, and immunity to disease (they release antibiotics to fend off invading organisms). The fungal networks also enhance the soil structure, which means better air and water circulation and root support. There are now lines of mycorrhizal products, such as Fungi Perfecti’s MycoGrow, available to farmers, gardeners, and landscapers.
All good—but it’s important to know that mycorrhizal and synthetic brews don’t mix. “Mycorrhizal fungi are inhibited by the use of water-soluble nitrogen and/or phosphate fertilizers, herbicides, insecticides and, of course, fungicides,” says Jones, noting that for this reason, “we do not find them in abundance in conventional agriculture.” In crop fields left fallow, without any plant cover, the mycorrhizal network literally starves to death. They’re also disrupted by tilling; stick a shovel in the soil and you’re likely to fray those delicate tendrils. In a kind of biochemical treadmill, a grower may be adding fertilizers and other chemical agents to bolster a crop that’s languishing mainly due to the loss of mycorrhizal associations. Reflecting the fungi’s role in drawing carbon into the soil, Christine Jones says that when fungicides are used, “carbon flow will be stopped before it even starts.”
How much carbon can be brought into the soil and stored? According to Jones, “under appropriate conditions, 30 to 40 percent of carbon fixed in green leaves can be transferred to soil and rapidly humified, resulting in rates of soil carbon sequestration in the order of five to 20 tonnes of CO2 per hectare per year.” If we wish to “revitalise all terrestrial life forms, including people,” she says, the way to do so is to restore the soil battery. This means creating the conditions for the liquid carbon pathway to flow uninterrupted in the soil, giving biology the chance to do its thing.
In talk of global environmental crises, we hear a lot about carbon dioxide, but we don’t hear much about soil. However, international organizations, including the UN, are beginning to address global soil degradation as a threat to food and water security. Globally, each year some seventy-five billion tons of soil is lost. That would cover about thirty-eight thousand square miles of arable land, an expanse larger than the nation of Austria. The phrase peak soil has begun to appear in media reports. In the United States, Cornell soil scientist David Pimentel says that 90 percent of our cropland is losing soil to wind and water erosion at thirteen times the rate that soil is being formed. Given that we depend on these vanishing soils to support a growing population, the pace of erosion and land degradation has become a matter of increasing concern.
To Christine Jones, sequestering carbon and creating soil are the same thing; by maximizing the liquid carbon pathway, you’re kick-starting the process of building soil. This single insight frees us from the assumption that soil generation is something that can only occur over geological time. The belief has been that topsoil isn’t something one can just “make.” Therefore, the best we can do is to try to preserve what we’ve got and somehow bide our time for the five hundred years needed to grow a measly inch of the stuff. Conventional wisdom is that soil organic matter forms in the top layer of soil, the product of degrading biomass. True, this uppermost stratum of soil is highly biologically active, with decomposer fungi breaking down the organic residue; this mechanism both stores carbon and releases carbon dioxide into the air. However, thanks to the liquid carbon pathway, the mycorrhizal fungi, in partnership with their botanical hosts and via the carbon-holding properties of glomalin, are also making humus. This means of generating soil organic matter emits far less carbon dioxide— the transfer of carbon takes place underground.
This alternative route to soil building is significant for a few reasons. First, the carbon that accumulates near the soil surface, say in the first four inches, says Jones, is mostly “short-chain, labile carbon, indicative of rapid turnover.” This “restless” carbon is critical to the soil food web, the community of organisms that reside in the earth’s upper stratum. With the carbon in flux, however, it’s not so effectively stored. The more deeply the carbon can be stowed away, the more securely it is preserved and the greater its contribution to soil structure and function over the long term. This highly stable carbon is enhanced in the lower soil profile via the liquid carbon pathway; the surface carbon, most of which oxidizes, rarely makes its way to the stable lower substrate.
Also, it calls attention to biological dynamics occurring at depth, which, says Jones, are generally ignored. The Kyoto Protocol, for instance, only addresses carbon sequestration down to thirty centimeters (one foot). In an article called “Carbon That Counts,” passed around soil circles like a 1970s rock bootleg among music fans, she writes: “Routine assessments of agricultural soils rarely extend beyond the top 10 to 15 centimeters and are generally limited to determining the status of a small number of elements, notably phosphorus (P) and nitrogen (N). Overemphasis on these nutrients has masked the myriad of microbial interactions that would normally take place in soil; interactions that are necessary for carbon sequestration, precursor to the formation of fertile topsoil.”
At depths below a foot soil does form—more rapidly than in the soil’s upper horizons, Jones contends. Here’s how: The liquid carbon compounds that are pumped down by the plant bolster the stores of organic matter. At the same time, the liquefied carbon stokes the earth-dwelling microbes, which get to work dissolving the mineral portion of the soil. These minerals at once feed the plant (remember, the mycorrhizal fungi are busy making mineral exchanges down there at root level) and build humus at a fast clip. In Jones’s words: “A large proportion of the liquid carbon is humified. That is, it’s transformed to humus, a stable form of soil carbon that has amazing properties, not the least of which is the rapid conversion of compacted subsoils into soft friable topsoils, dramatically improving soil depth and function.”
You got that? One farmer I met, Gene Goven of Turtle Lake, North Dakota, put it more succinctly: “You build soil where the roots go—down!”
The humus, formed at lower depths, advances the goal of carbon sequestration because it is more stable. It’s what Jones characterizes as “carbon that counts” in that it’s more resilient than carbon in the top layer, the level that’s typically measured. It doesn’t disappear in a drought, the way surface organic matter, formed by decaying biomass, is more prone to do. It retains minerals and water so that these are accessible to plants as needed, and therefore creates the environment for better food production.
With the plant’s carbon pump driving the process, humus-rich topsoil forms downward, well beneath the surface. That is, as long as the mycorrhizal networks stay intact. “The positive feedback loops render the liquid carbon pathway somewhat akin to perpetual motion,” says Jones. “You can almost see new topsoil forming before your eyes.” Since the liquid carbon pathway streams dissolved carbon through a plant’s root system, all this is happening beneath the usual threshold of observation. So according to standard carbon modeling, this process doesn’t exist.
Sequestering carbon dioxide and generating high-quality topsoil in one go? This sounds great. There are just two problems, both of which cause Jones—a woman who wants to get things done—no end of aggravation: One is that the scientific/agricultural establishment doesn’t believe it. The other is the touchy matter that the chemical additives beloved by many government institutions and industry have a tendency to mess it all up.
Let’s tackle the second one first.
If the first transformative revelation for Jones was that soil was a crucible for so many agricultural and ecological challenges, the second was the realization that those entities with the power to do something about soil—large agricultural services companies, whether governmentor privately funded—didn’t really want to know about it. In a sense this was another “paradise lost,” in that she worked in conjunction with educational and governmental agencies for more than two decades under the assumption that they shared the goal of improving the land and its ecological viability.
The great learning for me was to understand the implications of the enormous industry that depends on us not finding solutions to problems in agriculture. These so-called “problems” generate income for the ever-expanding ancillary industries including the manufacture of synthetic fertilizers, herbicides, insecticides and fungicides. Far greater profit is derived from developing, manufacturing, marketing, transporting and applying toxins—to the food we feed our kids—than is made by farmers. Indeed, the major portion of farm income is now expended on the inputs required to maintain production as soil function fails.
The emphasis on nutrients like nitrogen and phosphorus, she says, has obscured the importance of mycorrhizal and microbial interactions that create soil and sequester carbon. Not only that: The presence of high levels of nitrogen from fertilizer sends a signal to plants to reduce the supply of liquid carbon to microbial symbionts, effectively inhibiting the microbial associations that would otherwise supply atmospheric nitrogen for free.
As time went on Jones became outspoken about topics like CSIRO, Australia’s preeminent scientific research body, forging alliances with (in other words, accepting money from) such corporations as Bayer CropScience, which sells genetically modified (GM) canola. This won her few friends among agricultural power brokers. She told Australian Broadcasting Corporation’s news show Landline, “People, sometimes nicely, say I’m a lone visionary. When they are not being nice, they say other things that I won’t repeat.” Her views on soil building and what she refers to as “the microbial bridge” are dismissed due to “lack of data,” and her research is dismissed because the results confound conventional beliefs.
Industrial expediency is one factor; lack of confirming documentation is another. One reason people aren’t paying much attention to mycorrhizal and microbial activity, says Jones, is that government- and industry-funded research sites tend to be located on conventionally managed land, which doesn’t exhibit natural plant–soil dynamics. “In most of today’s agricultural soils, the sequestration pathway is not there. The microbial bridge—the biological processes that build soil carbon and humus—has been blown by chemical additives.”
Now the other problem: No one believes it’s possible to build top-soil this fast.
As an example, let’s leave Christine Jones and head a few hundred miles southwest toward Gulgong, a former gold-mining town in the Central Tablelands of New South Wales, near which Colin Seis runs a two-thousand-acre farm. The farm, Winona, has become Australia’s Exhibit A for accelerated soil creation. Fifth-generation farmer Seis is now as well known for “pasture cropping,” the land-management model he helped develop, as for the (gnarly, stout) merino sheep and (winsome, long-eared) kelpie working dogs his family breeds. This farming technique has turned out to be an ideal approach for rapidly building soil.
Pasture cropping, a method of sowing annual cereal crops into perennial (preferably native) pasture, was initially devised by fellow fifth-generation farmer Darryl Cluff, who describes the technique in his 2003 book Farming Without Farming. When Cluff assumed management of the family farm, Olive Lodge in Birriwa, near Gulgong, the land was in a sorry state. His quest to figure out how to restore the farm led him to examine Australia’s farming history—and seek ways to reclaim what was lost.
“Our early European history records that Australia was a country with vast areas of grasslands, as well as huge areas with scattered trees,” says Cluff. “It seemed to me that the grassland community became so efficient at survival that they were out-competing the trees.” These native grasses, however, were depleted by decades of intensive grazing; they were seen as having little value and were often replaced by non-native annuals.
“The trouble is that these [native] plants are not well understood, the seed is very difficult to harvest and the plants have specific requirements for their establishment,” says Cluff, who helped form an organization called Stipa Native Grasses Association, which focuses on practical applications of native grasses. “It takes a very long time for quality native pastures to naturally re-establish after a cropping phase. However, our native pasture plants were always there, the last feed available during drought and the first to respond to the rain when it finally came. I thought that they had tremendous value, but they didn’t quite fit in with our farming system. My thoughts were on how to grow profitable crops without the cost of re-establishing pastures.”
So he left the pasture there. In 1995, after an eighteen-month drought that only added urgency to these questions, Cluff direct-drilled an oat crop into a pasture of dormant native redgrass (Bothriochloa macra)—and despite the scant moisture, the crop thrived. A year later, Seis began pasture cropping, too. When Cluff chose to concentrate on his own farming business—due in large part to criticism from the agricultural bureaucracy for his departure from standard practice—Seis began promoting pasture cropping among other farmers.
And Winona became the showcase. The two-thousand-acre property has been in Seis’s family since the 1860s, when his great-great-grandfather started a sheep and wheat operation. Seis’s father, Harry, took over in the late 1920s and grew wheat conventionally (with lots of heavy machinery) and prospered. That is, until the soil began washing away. To address the degraded soil conditions he turned to government-subsidized superphosphate fertilizer and was extremely successful, particularly during the postwar wool boom. By the 1970s and ’80s, the soil was acidic, the water table increasingly saline, and weeds were taking over. In 1979, after a bushfire that destroyed most farm buildings and killed three thousand sheep, Colin dispensed with the fertilizer that had gone up in price and was now costing him tens of thousands of dollars each year. He turned his attention to the native grasses—redgrass, spear grass, kangaroo grass, wallaby grass, and others—that flourished once they weren’t competing with phosphate-loving plants.
When you look at a pasture-cropped field at maturity you see the crop, row after row of grain standing tall in tufts. But rather than emerging from a brown base of tilled soil, the plants are rising from a bed of green pasture. The original concept was to find a cheaper way of sowing oats to feed the animals. But what Cluff and Seis stumbled upon was a means of re-creating the biological community of native grasslands. In natural grasslands annual and perennial plants coexist, each benefiting the other. Broadacre farming, which removes existing ground cover so that crops are sown on cleared fields, damages soil structure, interrupts fungal and microbial associations, and releases stored carbon. Pasture cropping, by contrast, leaves soil dynamics intact. It also supports a variety of plants, in particular many deep-rooted grasses engaged in carbon–mineral–water exchanges underground.
At Winona, Seis saw a difference after two years. The land developed better resistance to drought, a greater diversity of plant, insect, and microbial species, higher soil carbon levels (a 200 percent increase over ten years), and an overall improvement in ecological function. Productivity improved, since the perennials reseed (so there’s no need to sow). And the perennial ground cover means constant protection from wind and water erosion.
Pasture cropping “mimics the function of natural grassland, where perennial and annual species grow symbiotically,” says Seis. “It may be that the direct drilling of the cereal crop into pasture when it is dormant provides food for the bacteria and fungi at a time of year when natural pasture is not active. At the same time, managing pasture for native perennial grasses means they can grow to full expression. This way they maintain soil structure and store sufficient root reserves to be involved in nutrient trading.” The only downsides to pasture cropping are the need to buy or alter machinery and that crop yields might dip, particularly at the outset. But increased profits from combining pasture and crop production on the same land should more than offset this.
As for soil building, over a ten-year period the depth of topsoil more than quadrupled—from four inches to eighteen inches. Christine Jones, who has compared soil at Winona with soil on adjacent paddocks, notes that this was during a period of below-average rainfall in the region.
Seis expresses concern that among science organizations in Australia, “most innovative land-management practices are not taken seriously. Recently the NSW Department of Agriculture measured soil carbon increases on my farm ‘Winona’ which showed an increase of over 160% to a depth of half a meter. They are now disputing their own data and are not going to use this data in their overall research in carbon sequestration using pasture cropping techniques, even though the site on my farm is the second-oldest ‘pasture cropped’ site in the world.” Seis says pasture cropping is now being practiced on two thousand farms and ranches around the globe.
In one instance, Christine Jones saw her own research used to “prove” that landowners could not “afford” to focus on building soil carbon because, according to five top-ranking CSIRO scientists, the necessary nitrogen, phosphorus, and sulfur supplementation would be too costly. The rationale for the CSIRO paper was that such inputs would be necessary. (One of the authors used this assumption to question Colin Seis’s significant increases in soil carbon at Winona.) What these scientists failed to take into consideration was that in highcarbon, high-functioning soil with the liquid carbon pathway intact, soil microbes are able to fix nitrogen and release phosphorus and other elements, making them available in a plant-accessible form.
“Institutional soil scientists, funded by agrichemical companies, are doing their utmost to prevent this information being accepted because the humification process (and hence the storing of the sun’s energy in the soil) does not proceed where there are high levels of chemical inputs,” says Jones. “Once farmers ‘get’ this, the big end of town (in the ag world, at least) will have nothing to sell. Farmers will not want to use toxic chemicals because their use results in soil degradation—which is a symptom of the loss of soil energy.”
On a more hopeful note, she adds: “Paradise has been lost on much of our agricultural land, but I know it can be regained.”
The idea that soil can accumulate rapidly is not new. Charles E. Kellogg, a professor of soil science with the Natural Resources Conservation Service, wrote in 1949, “Some people speculate about how much time is required ‘to build an inch of soil material.’ The answer could well be, ‘somewhere between 10 minutes and 10 million years.’”
One tool that reportedly allows for faster soil building is the Keyline plow and design system, originally developed in the 1940s by P. A. Yeomans, a farmer and engineer (and his son, Allan Yeomans, who wrote Priority One, which inspired Abe Collins). The chisel-shaped plow decompacts and aerates the subsoil with minimal disturbance; water can infiltrate and conditions improve for fungi and microorganisms. With Keyline plowing and planned high-density grazing, Yeomans was reportedly able to produce four inches of humus-rich soil in three years, starting with bare, sandy ground.
“You can build soil fairly quickly,” says Courtney White, co-founder and director of the Quivira Coalition, a nonprofit based in Santa Fe, New Mexico, devoted to the economic and ecological vitality of western working landscapes. He has visited several Australian farms, including Winona. “With caveats—it depends on the rain, worms, and condition of the land. Most folks think that with soil, it’s all downhill. Ranchers are building soil. But they don’t think about it in the climate context. They want the grass to grow. The challenge is how to scale it up. For building soil, what’s important is not so much the weathering of rock and minerals but the biological processes. When we think in terms of chemistry or geology it’s one thing. If you think of biology, it’s very different.”
This echoes Yeomans’s understanding of building soil: “It merely has to convert the sub-soil into fertile soil. The length of time that this takes is related to the life cycles of the life in the soil.” To quicken these life cycles, the Keyline system combines the deep-reaching chisel plow with grazing timed so as to stimulate plant growth.
On a visit to North Dakota, Gene Goven showed me some before-and-after slides that portray changes on his land since he implemented Holistic Management (his story is in chapter 6). “Here we had hardpan because of tillage,” he said, meaning that the top layer of soil was compacted and impervious to water. “The roots only went down three to five inches. After 90 days of soil building we had ten inches of aggregate structure. We built six inches of topsoil in one season, soil that didn’t exist in the spring. How many years does it take to build topsoil? Five hundred? We build soil down—that’s the paradigm shift. It can be done. I’m doing it.”
Abe Collins combined using the Keyline plow with Holistic Planned Grazing in northern Vermont, and says that in one year they went from eight inches of topsoil on top of gray clay to sixteen inches of topsoil. “We used the Keyline plow in the sequence that Yeomans discovered changes subsoil into topsoil: graze the grass, subsoil to a few inches below the current topsoil layer, allow for regrowth, graze again. The ‘soil conversion phase’ of Keyline is usually suggested to last for about three years. In this time, one would subsoil at least once per year. The soil changed as predicted by Yeomans and other practitioners around the world who have worked with Keyline Soil Formation. We subsoiled ground twice that year, and that seemed to push the soil system to a new state.”
When I was up in St. Albans, I saw this soil as Abe dipped his shovel and grabbed a brown-black fistful and let it roll over his palm. But I didn’t see it six years ago, when he started his soil-bolstering regimen. Which is precisely the stumbling block: Anecdotal reports and fence-line comparisons are fine for practitioners sharing land-improvement strategies, but getting beliefs about soil creation to budge takes a body of evidence. As Peter Donovan says, to date “there’s not very much good data, no longitudinal study to measure changes over time.” This, he notes, was one motivation for pursuing the Soil Carbon Challenge, since increasing carbon and building soil are facets of the same process. Without the numbers, it’s too easy for agency bureaucrats and industry reps to say “we need solid data” and to dismiss these ideas as “pie in the sky” and individual claims as “tall tales.” It takes a long time to gather the figures. Unfortunately, we don’t have that time; the problems these methods could potentially solve are pelting us now.
With all these approaches to building soil and building soil carbon— the Keyline system, pasture cropping, Holistic Planned Grazing (the focus of the next chapter), or, most commonly, a combination of these—what’s key is the pace of photosynthesis. Barring interruptions to natural processes, the more photosynthesis is occurring per acre of land, the more carbon is being stored and the more soil is being made. The exchanges facilitated by mycorrhizal fungi, the fulcrum of what Christine Jones calls “the microbial bridge,” prime the plants for higher rates of photosynthesis. Another factor that promotes photosynthesis is greater leaf-surface area. Which means that any time plants are removed, as in field clearing or burning, photosynthetic capability is diminished.
Remember our bumper sticker—OXIDIZE LESS, PHOTOSYNTHESIZE MORE? That’s what’s happening here—the plants are taking in more carbon dioxide and storing more carbon.
As for the “oxidize less” part, the thing to avoid is bare soil: Without plant cover, soil carbon is prone to bind with oxygen and go airborne. The plant overlay also buffers temperature and slows evaporation, establishing conditions for microorganisms to thrive, thus galvanizing plant growth, which in turn stimulates photosynthesis. Soils depleted of carbon are oxidation risks. With inert soil the liquid carbon pathway runs into a dead end; rather than entering the soil food web, the carbon oxidizes and returns to the atmosphere as carbon dioxide.
Which does our current mode of agriculture favor? By planting annuals and plowing and clearing so that the soil is open to the elements for much of the year, we’re managing for oxidation instead of photosynthesis, regardless of whether we realize it or not.
“We create so much bare soil in conventional agriculture that a lot of the sun’s energy is dissipated as heat rather than converted to biomass,” says Jones. “Every kilogram of glucose produced via the photosynthesis process represents 16 megajoules of sunlight energy bound in a biochemical form. If that same amount of light falls onto bare ground rather than onto a green leaf, the energy is radiated back to the atmosphere.” Peter Donovan likes to refer to spots of bare ground as “sunshine spills,” creating a parallel with an oil spill that might occur when a pipe leaks or something otherwise goes wrong. The potential of the energy has been lost.
Depending on what you put on and in the soil, you’re managing either for photosynthesis or for oxidation. These tracks are self-reinforcing; you’re launched onto one trajectory or another: toward carbon sequestration and soil health or toward carbon depletion and soil degradation. For example, more leaves mean more photosynthesis. Robust leaves also mean more roots, which means more carbon streaming into the soil. Which means, at once, greater fertility and more carbon sequestered. Steering land on a positive course can happen very quickly; Jones says changing “from annual to perennial groundcover can double levels of soil carbon in a relatively short period of time.” In addition to uninterrupted photosynthesis, perennial plants are continually pumping carbon and playing host to mycorrhizal and microbial activity. (Provided those perennials are managed appropriately, which is the subject of the next chapter.)
Bare ground sets in motion a different set of circumstances: moisture loss, less food for microbes, and therefore less microbial activity, which results in fewer nutrients for crops, leading to less-than-vigorous leaves, less photosynthetic activity, and less carbon flowing through the roots and being cached in the soil. Each contingency perpetuates the downward spiral. Says Jones: “When carbon sequestration stops, soils lose structure—like decomposing wood. And, like a dead tree, soil no longer functions as a living, growing thing.”
But we needn’t head down that road; at every juncture there’s a choice, and for every mechanism there are two ways to look at it. As Jones says, “Every tonne of carbon lost from soil adds 3.67 tonnes of carbon dioxide to the atmosphere. Conversely, every one tonne increase in soil organic carbon represents 3.67 tonnes of CO2 sequestered from the atmosphere and removed from the greenhouse gas equation.”
As for the arithmetic of food, Jones says, “According to those who are good at math (which doesn’t include me!) the planet’s current vegetative cover captures around 3000 EJ of the sun’s energy. This photosynthetic capacity would appear to be sufficient to feed only 3.3 billion people. The other 3.7 billion people, then, are being supported by photosynthetic energy captured in past eras, embodied in fossil fuel.” By restoring the capacity of the world’s soils, however, we can do better. To offer one example, Jones notes that Colin Seis’s land can carry twice as many livestock animals per acre as neighboring land. “In other words, it can feed twice as many people.”
Nitrogen and Soil: A Cautionary Tale
Nitrogen (N in the periodic table) is essential to all life, and forms the basis of proteins, genetic material, and enzymes. Availability of nitrogen is often a limiting factor in growing crops. Not for lack of nitrogen per se: Nitogen gas, N2, comprises nearly 80 percent of the atmosphere. But in its gaseous form, N2 is a highly stable molecule that plants can only access in certain ways: via the breaking of the N2 bond through lightning and the element’s subsequent descent by rain; or through the activities of nitrogen-fixing bacteria in the soil or on the root nodules of legumes. Plant-usable nitrogen is also present in manure and humus, but is released slowly so is, well, limiting.
All of this changed in the early twentieth century with the discovery of the Haber-Bosch process, which converts nitrogen gas to nitrogen-based fertilizer on an industrial scale. The manufacture of nitrogen fertilizer was a key component of the “Green Revolution” beginning in the 1960s. (With a slight detour into nitrogen-derived explosives, like nitroglycerin and TNT.) Crop yields soared, enabling the dramatic growth in world population, and, in this country, cheap food. Thanks to modern chemical innovation, we seemed to have broken the Malthusian barrier: the notion that population growth will always exceed expansions in agricultural output.
Because no caution was taken, this becomes a cautionary tale. By the 1990s, the increase in yields hit a wall. Particularly in the United States, where low fuel costs meant fertilizer was cheap, the response was to add more. The Law of the Minimum—that a plant’s capacity to grow is determined by the scarcest nutrient, popularized by Justus von Liebig, the nineteenth-century scientist who pinpointed nitrogen’s role in allowing plants to thrive—became the Law of the Maximum: better to put on more fertilizer than risk a bad crop. Globally, the amount of nitrogen applied to agricultural land is rising about 15 percent a year.
Global dependence on nitrogen fertilizers has led to several problems:
1. Soils reach a nitrogen saturation point, and the excess either oxidizes to become nitrous oxide (N2O), a potent greenhouse gas, or leaches into water as nitrate. In any body of water this can lead to algal blooms and hypoxic zones. In sources for drinking water, nitrate poses a health hazard.
2. It had been thought that fertilizers bolstered soil carbon because rapid plant growth meant more decaying biomass. However, research is finding the opposite, that synthetic nitrogen depletes soil carbon. It speeds up growth of microorganisms that feed on nitrogen at the expense of other soil dwellers, and these turbocharged microbes proceed to consume the humus.
3. Long-term use of nitrogen fertilizers acidifies soil, which leaves plants vulnerable to diseases and pests, particularly those that flourish in acid environments. Acidic soil also interferes with a plant’s ability to take up minerals and nutrients, including, ironically, nitrogen.
4. Synthetic nitrogen fertilizer creates in the soil a classic addiction scenario: Because the soil is depleted, it can’t function without help. The only thing that does the trick is another hit of nitrogen. This masks the underlying problems, even as the soil is further compromised.
5. The manufacture of chemical nitrogen fertility relies heavily on fossil fuels (including, in places like China, dirty coal). On a conventional farm, production of the fertilizer it uses accounts for nearly a third of its total energy consumption.
The use of artificial nitrogen fertilizer short-circuits the biological nitrogen cycle. In so doing, says Christine Jones, “It wreaks havoc on the organisms that make soil fertile. Adding synthetic nitrogen inhibits the microbial associations that would otherwise enable plants to access some of the 78,000 tons of nitrogen that sit above every hectare of land. However, if farmers and gardeners support microbial activity in the soil, there will be no need for inorganic chemical fertilizers.”
Can those who grow our food forgo the lure of fast nitrogen? It will be a challenge, since today the production of these fertilizers involves an interconnected complex of the agricultural, energy, chemical, and explosive industries, bonds proving every bit as tough to crack as that of the original N2 molecule.