More resources related to this pocket guide, including a pdf version and an online app, are available at landstewardshipproject.org/smartsoil. Paper copies are available from one of LSP’s offices:
This publication was produced by the Land Stewardship Project (LSP) as a guide to the ecological and agronomic science behind an exciting new area of soil-friendly agriculture, and how farmers are undertaking steps to make their operations “soil smart.” Such farms are integrating innovative ways of producing crops and livestock to build the kind of healthy soil that can clean up our water while sequestering greenhouse gases, bolstering profits and mitigating extreme weather risks. Granted, there are barriers, not least of which is a market system that, combined with federal farm policy incentives/penalties, supports the monocultural production of commodity crops. It can seem risky to buck such an embedded system, but farmers and researchers are leading the way with sound practice and sound science to develop real solutions.
This pocket guide provides policymakers, educators, journalists and the general public the basic information needed for developing a framework that supports a thriving soil ecosystem. We invite you to read the short chapters, look at the graphs and get acquainted with the new science and innovative practices that are shaping this movement. And we particularly encourage you to read the sidebar stories on the farmers who are leading the way on building soil health.
Research and writing was conducted by Brian DeVore, with assistance from LSP executive director Mark Schultz and LSP science and special projects lead George Boody, as well as staff representing LSP’s Bridge to Soil Health, Chippewa 10%, and Policy and Organizing initiatives. Funding was provided by the McKnight Foundation, the Rachel Golden Foundation and the No Regrets Initiative.
LSP is a private, nonprofit, membership organization founded in 1982 to foster an ethic of stewardship for farmland, to promote sustainable agriculture and to develop healthy communities. LSP’s work has a broad and deep impact, from new farmer training and local organizing, to federal policy and community based food systems development. For information on becoming a member of the Land Stewardship Project, see landstewardshipproject.org/donate, or call 612-722-6377.
The twin problems of polluted water and climate change share a common solution: the building of soil carbon via farming practices that protect the landscape’s surface and generate biological activity below.
This is an exciting time in agriculture. Advances in sustainable farming techniques, coupled with scientific breakthroughs in understanding the most diverse ecosystem on Earth, have generated an unprecedented amount of interest on the part of crop and livestock farmers in the health of the soil that provides their livelihood. Such a focus on “soil smart farming” during the past half-dozen years has created opportunities for farmers to build more resiliency in the face of extreme weather conditions, disease outbreaks, market fluctuations and other problems that plague agriculture.
“The most important characteristic of an organism is that capacity for internal self-renewal known as health.”— Aldo Leopold
This “soil health revolution” can produce important benefits beyond the boundaries of crop fields and pastures. In fact, building healthy, functional soil can play a critical role in helping society deal with two of the most pressing environmental problems it faces today: water pollution and climate change. Perhaps what’s most exciting about farming practices that can help clean our water and sequester greenhouse gases that cause climate change is that they are not theoretical, “far off in the future” type techniques. Soil friendly farming is being practiced today throughout the Midwest, as well as other parts of the world. These systems and techniques, which are proving to be profitable and practical, vary in their scope, the ways they are executed and the details of what technology and management skills are required to use them successfully. However, they have one thing in common: the ultimate result is that they increase soil organic matter, which, it turns out, can play a key role in cleaning up our water and mitigating climate change.
This pocket guide provides an introduction to the latest innovations in science and farming related to building soil health, and how implementing such practices on a wide scale basis can make agriculture a powerful force for creating a landscape that is good for our water and our climate.
Water pollution caused by agricultural runoff has become increasingly worse in recent years. A Minnesota Pollution Control Agency (MPCA) assessment found not one lake and only a few streams in Minnesota’s southwestern corner meet the state’s quality standards for fishing and swimming. High levels of bacteria, nitrates and sediment, much of it from agriculture, have caused this situation, according to the MPCA.1 High nitrate levels in rural well water caused by fertilizer runoff can lead to “blue baby syndrome” in infants, a type of asphyxiation.2 In Wisconsin, one in five wells in heavily agricultural areas is now too polluted with nitrate for safe drinking, according to that state’s Department of Agriculture, Trade and Consumer Protection.3
There’s more: in 2015, the Des Moines Waterworks sued three northwestern Iowa counties, claiming drainage districts there act as conduits for nitrate to move from farm fields into the Raccoon River, a major source of water for 500,000 Iowans. Such contamination has forced the city to invest massive amounts of money in equipment just to make the water safe for drinking.4 Agricultural runoff led to massive algal blooms in Lake Erie during 2014. As a result, for three days Toledo, Ohio, had to shut down the drinking water system that services 400,000 people.5
On a larger scale, as of 2017, an oxygen poor “dead zone” in the Gulf of Mexico was the size of New Jersey (approximately 9,000 square miles), the biggest it’s been since measurements began.6 The dead zone, which has decimated fisheries in the Gulf, has its roots in a Midwestern farming system that has increasingly become dependent on monocrops of corn and soybeans. Raising corn, for example, requires heavy dosages of nitrogen fertilizer, and much of it — 20 percent or more in some cases — escapes through the soil profile as nitrate, making its way into drainage systems and eventually to the Mississippi, which drains into the Gulf, where it supercharges algal growths that gobble up oxygen.7 In fact, 70 percent of nitrogen making its way into Minnesota streams is escaping from cropland.8 Nitrogen flowing into the Mississippi from Minnesota and Wisconsin alone has increased 75 percent over the past two decades, which is a major reason why nitrogen levels in the Gulf have jumped 10 percent during the same period.9
Such problems are caused by “nonpoint” source pollution runoff, which is particularly difficult to control, since it comes from numerous places on the landscape, rather than one specific “point” source such as a storm sewer pipe emptying straight into a river. The latest U.S. Environmental Protection Agency National Water Quality Assessment shows that agricultural nonpoint source pollution is the leading source of water quality problems in our nation on surveyed rivers and streams, the third largest source for lakes, the second largest source of impairments to wetlands, and a major contributor to contamination of estuaries and groundwater.10
Climate change, which is bringing torrential rains to parts of the Corn Belt, as well as places like Houston, Texas, is exacerbating the problem. In short, more intense rains produce more pollution. In 2017, the journal Science published a paper showing that increased rainfall could increase nitrogen runoff as much as 20 percent by the end of this century, which would slash oxygen levels even more in not just the Gulf, but places like Chesapeake Bay.11
In general, farmers have tended to adopt conservation practices such as terraced hillsides, grassed waterways, controlled drainage, water and sediment control basins, and no-till cultivation as a way to address localized environmental problems such as erosion. However, those measures are overshadowed by an increasing dominance of a monocropping system of annual species — mostly corn and soybeans — that leaves marginal and even good land and soil vulnerable, and a changing climate that overwhelms traditional conservation techniques.
Such a highly risky, industrialized system has created a landscape of compacted, unprotected soils, which are increasingly unable to soak up precipitation at a normal rate. Fields planted to corn and soybeans cover the ground in green vegetation for only around 120 days of the year — the rest of the time the landscape is left exposed and bare during a long “brown season.” These unprotected soils, coupled with the increasingly intense rainfalls resulting from climate change, have created a situation where local drainage systems and municipal storm sewer systems are overwhelmed by all of the excess runoff. Instead of seeping slowly through healthy soil, water flows overland into rivers and streams, increasing considerably the amount of soil that is scoured off streambanks. Such watershed level erosion is canceling out the advances we’ve made during the past few decades in reducing field-level erosion.12
In 2016, for the third year in a row, the Earth set a record for the highest average temperature in recorded history. Warmer temperatures causing melting polar sea ice is just one result of releasing greenhouse gases into the atmosphere via the burning of fossil fuels, tillage of soil and destruction of forests.13
Land use in general contributes about a quarter of total human-caused greenhouse gas emissions, according to the journal Nature. Roughly 10 percent to 14 percent of emissions come directly from agricultural production and another 12 percent to 17 percent from land cover changes, including deforestation.14
“We have conservation measures that were built for a climate scenario we no longer have.”— Jerry Hatfield, director of the USDA National Laboratory for Agriculture & the Environment
Agriculture contributes to climate change in a number of ways. For example, since tillage- based farming began, most agricultural soils have lost 30 percent to 75 percent of their organic carbon, which has resulted in a tremendous amount of greenhouse gases in the atmosphere.15 Areas such as the former grasslands that now are home to the majority of our corn and soybean fields have been particularly hard-hit biologically. When diverse plant systems are replaced by monocultures of row crops, it isn’t just the field’s surface that becomes less diverse. For example, the microbial diversity in the soil that once dominated native prairie areas in regions like the Midwest has been “almost completely eradicated,” according to the journal Science.16
In addition, nitrogen fertilizer is a major source of nitrous oxide, a powerful greenhouse gas. The manufacture of nitrogen fertilizer is energy-intensive, and involves the release of extensive amounts of carbon dioxide, which is the primary greenhouse gas causing climate change. And when the nitrogen fertilizer is applied to cropland, bacteria feed on it, supercharging a process that results in the release of nitrous oxide.17 In fact, research at the 100-year-old Morrow Plots at the University of Illinois found that heavy doses of nitrogen trigger a process where microorganisms burn through the crop residue, and then break down the carbon in the soil itself. Over a 50-year period, this reduced yields in continuous corn by 20 percent, and released a significant amount of carbon dioxide.18
U.S. agriculture is being impacted by climate change in a number of ways. For example, increased pest and disease outbreaks, as well as extreme weather, are threatening the ability of farmers to produce food. One of the most noticeable impacts on agriculture are unprecedented rainfall events. In the Midwest, rainstorm events that cause flash flooding produce in excess of three inches of precipitation during a one- to four-hour period. Heavy rain events have increased 37 percent in the Midwest since the 1950s, compared with the earlier part of the 20th century. Over the past 100 years in the Upper Midwest, there has been a 50 percent increase in the number of days with precipitation over four inches. Modeling shows such trends will increase and intensify during at least the next 30 years.19
Drought and “micro-droughts” — short, intense periods of weather so dry that they threaten crops even after a period of heavy rains — have also increased across the U.S., particularly in the West, and they are expected to become more frequent in the central part of the country. Between 1980 and July 2017, inland flooding, droughts and severe storms cost an estimated $551 billion in damages in the U.S.20 That estimate does not include the final price tag of the damage caused by the unprecedented rains that inundated the Houston, Texas, region in August 2017 during Hurricane Harvey (one early estimate put the cost at $70 billion to $108 billion for that storm event alone).21 “One-thousand year” floods are occurring more frequently, overwhelming drainage systems and conservation measures that have been put in place in crop fields. Farmers are reporting that one cutting edge way to fight erosion, “no-till” crop production, is no longer effective as a single practice because intense rainfalls literally float crop residues off the surface of fields and wash away soil and nutrients.22
The twin problems of polluted water and climate change share a common solution: the building of soil carbon via farming practices that protect the landscape’s surface and generate biological activity below. In order to understand how healthy soil can clean up our water and mitigate climate change, one needs to understand the role carbon plays in our soil ecosystem. Carbon is the main component of soil organic matter, the energy-rich portion of the soil profile that’s made up of plant and animal residue, along with the tissues of living and dead microorganisms. The majority of soil organic matter is found in the top eight inches of soil and decreases with depth until it’s difficult to find past the three-foot level. Organic matter drives soil’s water-retention capacity, structure and fertility, and can be divided into two major categories: stabilized organic matter, which is highly decomposed and stable, and the active fraction, which is being actively used and transformed by living plants, animals and microbes. If the soil ecosystem was a house, stabilized organic matter would be the foundation and frame, and the active fraction would be the food in the kitchen.
Organic matter is an essential component of soil that is healthy enough to function biologically. Such soils consistently cycle nutrients, as well as handle, store and filter water. A functional soil has a diversity of microorganisms and is physically stable enough to resist being blown or washed away. Organic matter’s role as a key player in the soil biome cannot be overstated. For example, organic matter can hold 10 to 1,000 times more water and nutrients than the same amount of soil minerals.1 It controls everything from how much nutrition plants get and how much water infiltrates into the soil profile, to the amount of carbon the land can store. That’s the hard science.
In short, organic matter drives the entire soil food web. Organic matter is made up of about 58 percent carbon, so for every percentage increase in organic matter, there is a corresponding rise in carbon in the soil. That’s why increasing organic matter in soil is so closely tied to increasing carbon. The math is simple: the more organic matter in our soil, the more carbon that’s stored there.
The problem is, right now organic matter is being broken down and carbon released into the atmosphere, rather than building up in the soil. And the destruction of that organic matter is severely curtailing our ability to recapture carbon. Unbroken prairie soils can have as much as 10 percent to 15 percent organic matter. But because of intensive tillage, Midwestern soil organic matter levels have plummeted to below 2 percent, in many cases. Exposing the soil using the moldboard plow and other implements causes organic matter to oxidize into the atmosphere, releasing the carbon that was being stored there and reducing the soil’s ability to function. This means it has little opportunity to cook up its own fertility via the exchange of nutrients, making it increasingly dependent on applications of synthetic fertilizers.
In effect, the nutrient cycle is broken, leaving soil without the organic matter and corresponding biology needed to cycle, store and replenish its own fertility. In fact, reducing organic matter from 2 to 1.5 percent can reduce the nutrient holding capacity of soil by 14 percent.2 As was mentioned before, most agricultural soils have lost 30 percent to 75 percent of their original organic carbon since tillage began. Again, the math is simple: less organic matter means less stored carbon in our soil.
But here is the good news: it was long thought that farmers had a limited ability to increase organic matter content in their soils in a relatively short amount of time. However, cutting-edge science and on-farm experience have shown in recent years that in fact soil organic matter levels can be raised in farm fields in as little as three years.3 So why does all this matter when it comes to water quality and climate change? Subsequent chapters answer that question.
Seeing soil as a living entity that, when fed a balanced diet, can become self-sufficient, is a pretty big paradigm shift, one that goes counter to the conventional agricultural wisdom that has dominated society for over 150 years. The idea that we could use a few select sources of fertility to “feed the plant, not the soil,” was popularized by Justus von Liebig, a 19th century German chemist who is considered the father of the fertilizer industry. Liebig argued that if we simply focused on, among other things, applying fertility in the form of nitrogen, phosphorus and potassium (N-P-K), we would get exactly what we wanted: productive plants. Under such a scenario, soil was simply a medium for holding up the plant and passing on that fertility to the roots of the crop.
But in recent years, cutting edge science, much of it fueled by advances in electron microscope technology and microbiology, has helped researchers and farmers gain a new perspective on just how complex the soil universe is and what we can do to build its self-sufficiency through the use of continuous living cover and livestock.
One area of soil science that has undergone a particularly big shift in thinking centers around organic matter and what impacts various land use practices have on it. Dr. Ray Weil, a University of Maryland soil ecologist, concedes that when he was recently updating his seminal textbook, The Nature and Properties of Soils, he had to re-write the chapter on organic matter. Dr. Kristine Nichols says that as a soil scientist, she was taught that a farmer could not have a positive impact on soil organic matter in a typical lifetime. Today, soil experts agree that farmers can increase soil organic matter in a period of three to 10 years.1
That’s important, Nichols says, because in the case of organic matter, “You have something that’s less than 5 percent of the soil, but it controls 90 percent of the functions. Innovations on the part of farmers are forcing us to come at this from a systems approach and ask deeper questions.”
When it comes to water quality, the ability of healthy, functioning soil to manage precipitation better is important for a couple of reasons. For one, it means more water absorption and less runoff, which results in less soil and other pollutants making their way into lakes, streams and rivers. But just as important, healthy, functioning soil has better “aggregate” structure, which means it can resist being, in a sense, blown apart by storms and heavy rains that cause runoff and erosion. Besides reduced erosion and fertilizer runoff, soils high in organic matter provide another key ecological service by tying up and breaking down pesticides.
Healthy soil also requires fewer applications of chemically-based, inorganic fertilizers, such as nitrogen or phosphorus. That’s because its increased biological activity generates the fertility that plants need and organic matter stores available nutrients for plants. Organic matter is especially important in providing nitrogen, phosphorus, sulfur and iron. A soil with 3 percent organic matter contains about 3,000 pounds of nitrogen per acre. Twenty-five to 100 pounds of that may become available to plants in a given year. The University of Ohio estimates that each 1 percent of organic matter can hold the equivalent of $700 in soil nutrients per acre.1
Soil organic matter really is the resource for all seasons — it can help a field manage overly wet, as well as overly dry, conditions. Healthy, functional soil also warms faster in the spring due to the biological activity present. Since water binds to soil organic matter, the higher a soil’s organic matter content, the better its ability to soak up precipitation and make it available for plants during the entire growing season, while preventing it from pooling up on the surface or running overland into local waterways and lakes. One percent of organic matter in the top six inches of soil holds approximately 25,000 to 27,000 gallons of water per acre.2 In fact, the capacity of a soil to store and supply water to plants can be one of the biggest factors in determining the potential of a particular field to produce a crop like corn or pasture grasses.
Organic matter’s ability to provide various ecological services is one reason building soil health has emerged as a key conservation tool. In recent decades, great strides have been made in reducing soil erosion to “T”, or “tolerable” loss rates — that’s the rate at which soil can theoretically be lost and still replaced. But it’s become clear that even bigger strides in conservation could be made by increasing soil carbon content, or managing for “C.” One USDA Natural Resources Conservation Service estimate is that if all of our country’s cropland was managed for T, soil erosion would decline by 0.85 billion tons annually. If cropland was managed in such a way that C was increased, erosion levels would drop by 1.29 billion tons per year. In financial terms, managing for T is worth $16.5 billion annually; managing for C almost $25 billion per year.3
As a result of unprecedented increases in average temperatures around the world, we are already seeing the damaging impacts of significant climate change: frequent flooding, intense and recurring pest outbreaks and severe droughts.1 Continued rises in global temperatures will cause further increases in the frequency and gravity of climate-related disasters. It’s been estimated that in order to keep within a temperature increase threshold that avoids truly catastrophic climate change, we need to reduce greenhouse gas emissions by 8 percent to 10 percent annually. Cutting energy use, along with clean energy technologies such as solar and wind, play critical roles in limiting emissions and should be pursued via both public policy and market based strategies. But such steps will only win us reductions of about 4 percent per year, at most.2
More carbon is in our soil than in the atmosphere and all plant life combined.
Many scientists are now saying that our best hope is to combine energy efficiency with finding ways to again make our soils net sinks for greenhouse gases. That’s where soil organic matter, and the carbon it contains, enters the picture. Soil used to hold tremendous amounts of carbon, and could do so again, using the latest knowledge and innovative plant and animal production systems. More carbon is in our soil than in the atmosphere and all plant life combined.3 And much more can be stored there.
Through photosynthesis, plants draw carbon out of the air to form carbon compounds. What the plant doesn’t use is exuded through the roots to feed soil organisms. This process makes for a stable form of carbon that is in effect stored in the soil. According to the periodical Yale Environment 360, some pools of carbon within soil aggregates are so stable that they can last thousands of years. The “active” carbon that’s present in topsoil, in contrast, is in a continual flux involving microbes and the atmosphere.4
According to numbers generated by Dr. Rattan Lal, director of Ohio State University’s Carbon Management and Sequestration Center, restoring soil health has the potential to store an additional 1 billion to 3 billion tons of carbon annually, equivalent to roughly 3.5 billion to 11 billion tons of carbon dioxide emissions. Annual carbon dioxide emissions from fossil fuel burning are approximately 32 billion tons.5 Writing in the journal Nature, scientists estimate that over a 20- to 30-year period, an additional 4 to 6.2 billion tons of carbon dioxide could be sequestered worldwide per year in crop and grazing lands by building healthy soil. Utilizing methods such as adding biochar (a form of charcoal) to soil would increase that amount by as much as 1.8 billion tons annually.6
Overall, there have been numerous estimates of just how much of an impact soil friendly agriculture can have on sequestering greenhouse gases. On the low end, scientists estimate 3 percent of global carbon emissions could be sequestered annually. Lal himself puts the potential range of how much carbon soil can sequester at 5 percent to 15 percent of annual global fossil fuel emissions.7 Again, it’s important to note that, as a strategy for addressing climate change, sequestering carbon in our soil cannot replace reduction of greenhouse gas emissions through conservation and the use of alternative energy. But without carbon sequestration, we will never reach the goals scientists say we must meet if we are to maintain a sustainable climate situation.
This brings up an important question: is there a limit to how much carbon our soils can sequester? Lal and other scientists studying soil and sequestration say in fact there is a point where soils will become “saturated” with carbon and unable to absorb more. However, the vast majority of the world’s soils are far below that saturation point. Also, it’s still unclear how much carbon can be stored deep within the profile past the typical root zone. Deep-rooted plants such as prairie grasses may provide a way to exude more carbon into the soil than we realize. Carbon sequestration research conducted in Australia at depths of nearly 130 feet shows that we may have just barely tapped the potential for storing greenhouse gases deep underground.8
So how do we create enough organic matter in our soil to produce clean water and mitigate climate change? We need a comprehensive approach to farming, one that utilizes a mix of current techniques fueled by recent innovations in soil science, agronomy and animal husbandry. There must be a focus on farming practices that keep soil from blowing or washing away, while creating the kind of underground universe that nurtures biological activity.
That means plants on top and roots in the ground, preferably 365-days-ayear, which is in stark contrast to the limited amount of time our current system of row cropping blankets the landscape. Keeping “continuous living cover” on the soil’s surface year-round can take many forms, from perennial grasses rotationally-grazed by livestock, to annual cover crops grown before and after the regular cash crop growing season.
As a sign of the key role continuous living cover plays in the livability of our planet, consider that NASA videos show carbon dioxide emissions rising significantly in the Northern Hemisphere during the winter and early spring months, when little live vegetation is present in places like the Midwest to absorb greenhouse gases.1 And, as far as water quality goes, agrichemical runoff into waterways tends to spike during spring planting, when soil is bare in a typical corn-soybean rotation.
There is nothing new about the idea of cover crops or rotational grazing. What is new is that recent science has revealed just how much such methods can build soil health, and the numerous benefits that result. This is knowledge that was not available to farmers and others in the agricultural community even just a few years ago. New techniques for grazing livestock and growing cover crops are making such soil-friendly methods more applicable to farms than ever — economically and agronomically. The next few chapters take a closer look at these methods.
In the Midwest, cover cropping often consists of growing small grains and brassicas (tillage radish, for example) on row cropped land before and after the regular corn-soybean growing season. For example, cereal rye may be interseeded into a growing stand of corn during late summer. Once the corn is harvested, allowing sunlight to reach the ground, the rye then has a few weeks during the fall to grow. During the winter, the rye provides protection, and living roots, for the soil until spring, when it will begin growing again, providing fertility and weed control for the new cash crop being planted.
“I feel we have to decide that perhaps the cost of putting in cover crops might have more value from the perspective of holding the ground where it is, because as soon as that ground washes away, due to these climate events that are out of control, you can’t get that ground back.”— southeastern Minnesota farmer Rory Beyer
Such a system results in numerous benefits for the land and water:
The number one method for cleaning up our water and sequestering greenhouse gases is rooted in getting more perennial grassland habitat established, as well as protecting what we already have. Grazing lands worldwide account for about one-fourth of potential carbon sequestration in our soils, and they already remove the equivalent of approximately 20 percent of carbon dioxide released annually as a result of deforestation and other land use changes.1 But perennial grazing lands are under siege. The Great Plains lost more grassland to agriculture in 2014 than the Brazilian Amazon lost to deforestation.2
The Great Plains lost more grassland to agriculture in 2014 than the Brazilian Amazon lost to deforestation.
If we are serious about building soil organic matter, and thus carbon, it is imperative that we find a way to integrate perennial grasslands and other forms of continuous living cover back into our farming systems. One key way to do that is by producing ruminant livestock — beef cattle, dairy cattle, sheep and goats — on the land. Animals out on the land help cycle nutrients and provide a way to add economic value to grass, small grains, cover crops and other plants that benefit the soil.
It’s important to keep in mind that it matters how those animals are placed upon the landscape. Simply turning them out onto open pastures or rangelands and allowing them to roam at will creates its own problems. Overgrazing destroys plant communities and is a major source of erosion and compaction, not to mention water pollution. But livestock are particularly good at building soil health when they are raised using various forms of what’s called “managed rotational grazing.”
This system consists of moving animals through a series of grazing paddocks on a regular basis — sometimes as much as once- or twice-a-day — so that they don’t overgraze the pastures or cropland. This distributes manure and urine across the landscape evenly, providing grasses and forbs an opportunity to take up the nutrients at a rate that fits their needs. Because it eliminates overgrazing and allows plants adequate time to recover after each pass of the animals, such a system can extend the pasture season by a month or more in the Upper Midwest and increase the total productivity of a pasture, which is a financial bonus for farmers.3
“Livestock are the rock stars of building soil health.”— Justin Morris, USDA soil health expert
The land beneath the surface benefits as well. Managed rotational grazing, along with its derivatives, such as mob grazing (high numbers of animals crowded into a paddock for short periods of time; often only hours), has been shown to supercharge biological activity as livestock use their hooves to work manure, urine and trampled vegetation into the soil.4 This protects the soil surface while making plenty of “food” available for the countless microbes and invertebrates that populate the world underneath.
Because of its ability to support a healthy soil habitat, rotational grazing has been shown to produce numerous benefits both in terms of water quality and the land’s ability to build organic matter and carbon:
Soil friendly farming systems are not pie-in-the-sky — an increasing number of individual farmers are implementing such practices on a consistent basis, proving they work in a variety of conditions. But what would happen if we were to integrate row crops, cover crops, livestock and pasture on a wider scale, producing continuous living cover throughout the region? Plenty, it turns out.
Halving the number of ruminant animals in North America doesn’t produce a system that sequesters greenhouse gases as long as we stick to our current soil-destroying industrialized cropping systems. What the science shows is that we need animals out there contributing to a nutrient cycle that builds and protects soil while giving farmers an economic incentive to keep the land covered all year-round.
A team of researchers from the USDA, Iowa State University, Texas A & M, Ohio State University and Michigan State University, among other institutions, collected years of peer-reviewed research results and compared the relative contributions of greenhouse gas emissions from various agricultural practices, both conventional and conservation-based.1 Their summary, which appeared in the Journal of Soil and Water Conservation, shows that it all comes down to how we treat the soil. When our land is tilled up and becomes vulnerable to erosion, it is a net exporter of greenhouse gases. What goes on beneath the surface matters as well. That’s why the researchers recommend a farming system that gets as much land as possible covered in continuous living cover 365-days-a-year. Their solution? Get livestock out on the land grazing continuous living cover.
The researchers cite several studies showing how managed rotational grazing can actually sequester more greenhouse gases than are being emitted. They emphasize the importance of integrating livestock, pastures and crop production — a perfect mix of enterprises in the Midwest. They outline a working lands scenario where a carbon-trapping farm may have some permanent pasture that is broken up into rotational grazing paddocks. But it could also be producing corn and soybeans in a system where cover crops like cereal rye or tillage radish are used to blanket that row-cropped land with growing plants before and after the regular growing season. These cover crops, when grazed, could provide low-cost forage for cattle and other livestock, helping justify the cost of the cover crop establishment while protecting the soil from erosion and building its biology. Cover crops can also help cut a farm’s reliance on chemical fertilizers, which are another source of greenhouse gases.
The paper outlines the “climate smart” potential of several farming scenarios in North America, from keeping our current industrialized system — typified by an increasing amount of grassland plowed under to make way for row crops and livestock confined in larger and larger concentrated animal feeding operations (CAFOs) — to utilizing a combination of managed rotational grazing and conservation cropping systems that involve no-till, diverse rotations and cover crops.
As Figure 13 shows, the differences are striking. Our current system of agriculture will continue to be a net producer of greenhouse gases, and things will only get worse as more of our world’s soil is damaged or lost. But even if 25 percent of our farming system is converted to managed rotational grazing/conservation cropping, agriculture will trap much larger amounts of greenhouse gases than it produces.
Under these scenarios, halving the number of ruminant animals in North America doesn’t produce a system that sequesters greenhouse gases as long as we stick to our current soil-destroying industrialized cropping systems. What the science shows is that we need animals out there contributing to a nutrient cycle that builds and protects soil while giving farmers an economic incentive to keep the land covered all year-round.
This wouldn’t necessarily require every farm to become a diversified crop/livestock operation. Under a more integrated system, diversity could be adopted on a more neighborhood basis. Even crop farmers who do not have livestock could utilize their neighbor’s animals to add economic value to their cover crops or that piece of pasture that hasn’t fallen under the plow yet. The managed rotational grazing/conservation cropping systems scenarios outlined in the Journal of Soil and Water Conservation aren’t just the stuff of fancy computer models — real farmers are taking advantage of such synergies in the Midwest and elsewhere every day.2
As this pocket guide makes clear, farming can play a major role in developing soils that build the amounts of organic matter and carbon required for clean water and a stable climate. In fact, without a vibrant soil ecosystem, other attempts to clean up our water or stabilize our climate will fall short. Healthy soil is not the only solution, but it is an essential component.
Here, we have chosen to focus on Midwestern agriculture, which, with its mix of innovative farmers and a basic infrastructure of crops, pastures and livestock, has tremendous potential to build soil carbon in a matter of years, rather than decades. This is already being proven on individual farms. Creating healthy, functional soil is doable and realistic.
Building carbon on agricultural lands will look different in both scale and method in other regions and other parts of the world. But no matter where the farm is located, the basic principle of generating healthy soil — utilize year-round diversity to protect the surface while building biology underneath — applies. What’s exciting about the new soil health revolution is that it can be carried out on a localized basis down to the watershed, farm, and even field, level. In a sense, building soil biology gives farmers control over their own destiny. Healthy, functional soil makes our farms more resilient not just ecologically and climatically, but also economically. After all, a soil that relies less on expensive inputs to produce crops and livestock, and that can resist the onslaught of extreme weather, is like money in the bank.
And healthy, functional soil on agricultural lands can also play a pivotal role in creating a positive future for our communities — local, regional and even global. Clean water and a stable climate benefit all of us, not just farmers and their rural neighbors. Healthy soil creates multiple benefits, many of which were not addressed in this pocket guide — from better wildlife habitat and healthier livestock, to the breaking down of toxic chemicals. Research even shows that soil with higher organic matter levels produces plants that pollinators prefer.1 Healthy, functional soil truly is a public good.
That’s why, if we are to see the farming systems outlined in this guide implemented on a widespread basis, we must as a society push to get more continuous living cover on the landscape. The status quo of increasingly less diverse production systems characterized by bare, lifeless soils for much of the year will not change of its own accord. That means supporting policy reforms, marketplace incentives and public investments that send a clear message: farming that builds healthy soil is a critical part of everyone’s future.
The Land Stewardship Project has produced a series of podcasts featuring the voices of farmers, researchers and conservationists who are on the cutting edge of building healthy soil. Check them out at http://landstewardshipproject.org/talkingsmartsoil.