ing the most effective ways to get carbon back into the soil in order to maintain productivity

Soil Carbon HOW THE SYSTEM WORKS Carbon input in soils occurs almost primarily via plant production. Plants Diamond in the Rough convert carbon dioxide into tissue and other compounds through photosyn- by Mike Amaranthus, Ph.D. metric tons), more than twice the car- thesis. Much of these compounds are bon in living vegetation (560 petagrams) allocated to root systems below the soil They say if you apply heat and pres- or in the atmosphere (750 petagrams). surface or to fuel the activities of benefi- sure to coal underground over time Unfortunately, however, on agricultural cial soil organisms such as mycorrhizal you can change it into a diamond, but lands, soil carbon has been lost at an fungi. As plants, roots and mycorrhizal farmers are trying to develop their own alarming rate. Carbon in the soil, in the threads in the soil die, they are decom- gem beneath the soil surface. Coal is form of organic matter, stable humus posed, primarily by soil microorgan- basically a fossilized lump of soil car- or glomalin, can be a “diamond in the isms. Through this process some of the bon: ancient plant and animal remains rough” for farmers due to the important carbon is stored in the soil and some is that we liberate to release energy. Today, role it plays in both the productivity and released through respiration back to the the estimated amount of carbon stored profitability of the farm. Considering atmosphere as carbon dioxide. Examples in world soils is about 1,100 to 1,600 the skyrocketing costs of conventional of stable soil organic materials are called petagrams (one petagram is one billion farm inputs, growers are rapidly learn- humus and glomalin. These residues can

Loss of carbon leads to degraded farm soil.

Reprinted from October 2008 • Vol. 38, No. 10 persist in soils for decades, hundreds or even thousands of years. The humus and glomalin compounds Carbon Sequestration: Amazing Numbers mentioned above are the dark black con- tent of a healthy soil — black due to the The Rodale Institute, researchers at Cornell University and the Agricul- tural Research Service have collaborated to develop estimates of carbon carbon content itself. They are critical sequestration in soils by implementing organic farming methods. When we for the soil’s biological activity, produc- apply these numbers to U.S. agriculture, some compelling insights emerge. tivity and profitability. This “bankroll” The bottom line is that U.S. agricultural lands, compared to other types of of stored energy is truly a gem when it lands, provide a tremendous opportunity to store carbon in soils (see table, comes to sustainable agriculture. below). • U.S. agriculture currently releases 750 million tons of CO2 annually into OUT OF SIGHT, OUT OF MIND the atmosphere. Converting all U.S. agricultural lands to organic production Leonardo da Vinci once said, “We would eliminate agriculture’s massive emission problem. In addition, switch- know more about the movement of the ing to organic production would actually result in a net sequestering of 811 celestial bodies than the soil underfoot.” million tons of CO2 per year. Soil still remains a great mystery. In to- • If just 10,000 medium-sized farms in the United States (2 percent of the total farmed area) converted to organic production, they would store so day’s high-tech society most people keep much carbon in the soil that it would be equivalent to taking 1,174,400 cars soil out of mind and out of context — off the road, or reducing car miles driven by 14.62 billion miles. yet what could be more important? All living things originate from the soil and eventually return to it. All great civiliza- tions, including the Egyptians, Greeks, Mayans and Romans, depended upon an adequate supply of fertile soil. These Carbon Storage Potential of U.S. Soils civilizations also declined when soil re- Potential % of the sources became thin due to erosion and Total Sequestration World’s bad management. U.S. % of via Organics Annual Throughout history, the story has Acres* Total (millions Global CO2 repeated itself. Great civilizations have Type of Land (millions) Acres of tons)** Emissions flourished where soils were fertile enough to support high-density human commun- ities, and fallen when soils could no longer Urban 60 2.6 30 3.1 sustain the demands put on them. The great early civilizations of Mesopotamia Rural Residential 94 4.1 47 4.9 arose because of the richness of their soils and collapsed because of declines in soil Golf Courses 1.2 0.05 0.6 0.06 quality. Poor land management, organic matter loss and excessive irrigation caused soils to become increasingly degraded, Lawns 38 1.6 19 2.0 leading to power struggles, migrations, and ultimately the collapse of the Fertile Corn 77 3.3 38 4.0 Crescent civilizations. Ancient Greece suffered a similar fate. Soybeans 72 3.2 36 3.8 The philosopher Plato, writing around 360 B.C., attributed the demise of Greek Wheat 46 2.0 23 2.4 power to land degradation: “[In earlier days] Attica yielded far more abundant produce. In comparison of what then Hay 66 2.9 33 3.5 was, there are remaining only the bones of the wasted body; all the richer and Total U.S. Cropland 442 19.2 221 23.2 softer parts of the soil having fallen away, and the mere skeleton of the land being * “Major Uses of the Land in the United States,” by Ruben N. Lubowski, Marlow left.” Plato’s reference to “lighter and Vesterby, Shawn Bucholtz, Alba Baez and Michael J. Roberts, Economic Information softer” was likely referring to organic Bulletin no. EIB-14, May 2006 There are 2.3 billion acres in the U.S.A. matter content of the soil. **Assuming the organic farming CO2 soil sequestration rate observed in the Rodale Many experts also blame the collapse Institute long-term farming systems trial of 3,670 lbs./acre/year. of the great Mayan civilization on soil

Reprinted from October 2008 • Vol. 38, No. 10 exhaustion and erosion, resulting from TAKING IT TO THE BANK ganic matter commonly disappears after agricultural practices and vegetation re- Carbon compounds in soil are an in- a few decades of tillage. In tropical soils, moval. According to Jared Diamond, a vestment that could easily be compared such losses can occur in under a decade. UCLA professor and author of Guns, to the workings of a modern day bank. Germs and Steel and Collapse, 90 percent Deposits and withdrawals are made by CARBON & ORGANIC FARMING of the people inhabiting Easter Island in the natural rhythm of root and mycor- For years, many have argued that or- the Pacific died because of deforestation, rhizal activity, decay and recycling. This ganically produced food is safer and more erosion and soil depletion. In Iceland, bank has been our central “financial nutritious. Now we are learning that a farming and human activities caused institution,” sustaining the human race switch to organic production methods is the majority of the soil to end up in the for millennia, although there have been an expedient and soil-based sink for re- sea, explains Diamond. “Icelandic soci- numerous times in our history, in large ducing carbon from the atmosphere. Da- ety survived only through a drastically geographical areas, where withdrawls ta from the Rodale Institute’s long-term lower standard of living,” he says. have exceeded deposits — resulting in comparison of organic and conventional These lessons of the past unfortu- biological bankruptcy. farming methods substantiates that or- nately do not seem to resonate in the Carbon compounds in soil enhance ganic practices are much more effective modern world. Today, we don’t think plant growth directly through both phys- at removing carbon dioxide, a major much about the ground beneath our iological and nutritional effects. Carbon greenhouse gas, from the atmosphere feet that supports our farms, cities and compounds improve root and mycor- and fixing it as beneficial organic matter in the soil. Organic practices result in rapid carbon buildup in the soil. The organic approach to sequestering carbon in soils does not rely on high-tech or space-age solutions. It takes advantage of the symbiotic relationships between plants and beneficial soil organisms such as nitrogen-fixing bacteria and mycor- rhizal fungi that have been successful at maintaining the productivity of the land for hundreds of millions of years. Research is revealing that practices such as reduced tillage, the use of cover crops, biological inoculants and ma- nures can dramatically alter the C stor- age of agricultural lands. Traditionally rotations of grass, clover, and alfalfa as well as manure and compost were used to replace soil organic matter lost to continuous cultivation. This method still works today. Experiments at Rotham- sted in the United Kingdom from 1843 Farmer Gerald Wiebe inspects his fall organic rye crop. to 1975 showed that areas treated with manure for more than 100 years nearly societies. Yet all of us intrinsically know rhizal development, uptake of plant nu- tripled in soil nitrogen content com- that good soil is just not dirt. When you trients, and serve as a source of nitrogen, pared to adding nitrogen as a chemical dig into rich, fresh earth, you can liter- phosphorus and sulfur. Indirectly, car- fertilizer. In the areas where chemical ally feel the life in it. Fertile, living soil bon compounds also affect plant growth fertilizer was used, nitrogen was either is chocolate brown and falls off your through modifications of physical, chem- lost in soil runoff or exported with the trowel and crumbles into small pieces ical and biological properties of the soil, crop. Additionally, a 15 year, side by side in your hand. It is light and easy and including an increase in water-holding study of corn and soybeans at the Rodale has an enticing aroma. It is the smell of capacity, the ability to retain nutrients, Institute in Pennsylvania, showed no life itself. The ability to recognize good and improvement of tilth and aeration difference in crop yields where legumes soil allowed our ancestors to survive through good soil structure. and manures were used instead of syn- and thrive for generations, and it is the In the last century, soil carbon has thetic fertilizers and pesticides. Organic carbon content of the soil that identifies been lost at a staggering rate due to and conventional cropping systems pro- this important resource. excessive tillage, erosion and the use duced similar profits and the soil carbon of chemical fertilizers. In temperate re- content for the organic plots increased gions, for example, half of the soil or- three to five times.

Reprinted from October 2008 • Vol. 38, No. 10 FRESH DATA FROM AN OLD EXPERIMENT Since 1981, the Rodale Institute Farm- Organic Material, ing Systems Trial (FST) has continuous- Organic Matter & Soil Carbon ly compared conventional and organic farming in side-by-side trials. This re- Many times we think of organic matter as the plant and animal residues we incorporate into the soil. We see a pile of leaves, manure or plant parts search provides a wealth of informa- and think, “Wow! I’m adding a lot of organic matter to the soil.” This soil tion about the ecological and economic amendment is actually organic material, not organic matter. benefits of organic farming that includes What’s the difference between organic material and organic matter? Organic detailed studies of cultivation, fertilizer, material is anything that was alive and is now in or on the soil. For it to become mycorrhizal fungi, weeds, compost, cov- organic matter, it must be decomposed into humus. Humus is organic material er crops, water quality and profitability. that has been converted by microorganisms to a resistant state of decomposi- The study contains convincing evidence tion. Humus is approximately 50 percent carbon and 5 percent nitrogen. that organic farming incorporates sig- Organic matter is stable in the soil. It has been decomposed until it is resis- nificant amounts of carbon into the soil, tant to further decomposition. Usually, only about 5 percent of organic matter compared to conventional farming. mineralizes yearly. That rate increases if temperature, oxygen and moisture The key to this process lies in the conditions become favorable for decomposition, which often occurs with soil tillage. It is the stable organic matter that is analyzed in soil tests. Organic mate- handling of soil organic matter. Because rial is unstable in the soil, changing form and mass readily as it decomposes. As soil organic matter is primarily carbon, much as 90 percent of it disappears quickly because of decomposition. increased levels of carbon directly cor- relate with carbon sequestration. While conventional farming practices typical- ly deplete soil organic matter, organic farming builds it through the use of composted animal manures, cover crops, Organic Matter & Carbon in Our Soils legumes and the activities of symbiotic mycorrhizal fungi and bacteria. An acre of soil measured to a depth of one foot weighs approximately 4 “Good organic farmers see carbon as million pounds, which means that 1 percent organic matter in the soil would a resource that improves crop quality, weigh about 40,000 pounds per acre and contain roughly 20,000 pounds of soil productivity and yield rather than carbon. Since it takes at least 10 pounds of organic material to decompose carbon as a waste product,” says Gerald to 1 pound of organic matter, roughly it takes at least 400,000 pounds (200 tons) of organic material applied or returned to the soil to add 1 percent Wiebe, an organic farmer in Manitoba, stable organic matter (40,000 pounds) under favorable conditions. Canada. Wiebe sees the value of active How much has been lost? Research indicates that organic matter content in management of the biological compo- the prairie regions of the United States and Canada have declined between 50 nent in soil to encourage carbon storage and 90 percent since the land was first cultivated. Let’s look at an example. Due in soil. “Some organic farmers tend to to organic matter converting to carbon dioxide, the organic matter in a top use a zero-input approach to organic foot of soil on a conventionally managed Iowa cornfield has decreased from 10 farming, thinking that sunshine, seed percent to 5 percent. How much soil carbon has been lost? How much CO2 has and rain are all they need. This often been released into the atmosphere? A reduction of 5 percent organic matter leads to decreased yields with no im- equals 50 tons of soil carbon (100,000 pounds) lost to the atmosphere. When provement in soil conditions. The simple oxidized, this 50 tons of carbon is equivalent to over 180 tons of atmospheric non-use of conventional inputs does not carbon dioxide released from a single acre! There are millions of acres of farm- land in the United States that have seen at least a 5 percent decline in total soil guarantee that soil microbial life, carbon organic matter content due to conventional farming practices. levels and soil structure will be restored. However, when mycorrhizal and bacte- rial inoculants, compost, compost tea, green manures, legumes, etc., are used in a well managed program, positive soil significant increase. In organic systems, matter? Following five basic steps can changes happen relatively quickly.” that converts to more than 1,000 pounds make the difference between storing or The FST is a long-term experiment of captured C (or about 3,670 pounds of releasing carbon in our soils. comparing three agricultural manage- CO2) per acre-foot per year. 1. Grasses and legumes. The periodic ment systems: one conventional, one use of grasses, grass legumes or legumes legume-based organic and one manure- THE 5-STEP in a crop rotation can add large amounts based organic. The FST’s two organic PROGRAM TO RECOVERY of organic matter to the soil. systems have shown an increase of 15-28 How do we stop burning up our soil 2. Continuous cover. This method percent in soil carbon, while the conven- organic matter to produce food? How keeps plants pumping soil with carbon tional system has shown no statistically do we conserve and increase soil organic year-round and supports the sequester-

Reprinted from October 2008 • Vol. 38, No. 10 Mycorrhizal-inoculated eggplant (left) exhibits increased yield compared to control plots. ing activities of beneficial soil organisms deposit carbon in soil. In the FST, soils and transporting these materials back to such as mycorrhizal fungi. The results farmed with organic systems have greater the roots. In exchange, the plant supplies are soil organic matter at higher levels populations of mycorrhizal fungi. Over- sugar and other compounds to fuel the than fallow-cropping systems. wintering cover crops supply energy to activities of the fungus. Miles of fungal 3. Conservation tillage. No-till or min- fuel the activities of mycorrhizal fungi filaments can be present in an ounce of imum tillage reduces organic matter de- in the organic system, in contrast to the healthy soil. The crop’s association with composition and release of carbon from conventional systems, which have a sig- mycorrhizal fungi increases the effective the surface soil. In the process, it also nificantly greater fallow period. Reduced surface absorbing area of roots several increases the physical structure of the chemical use in the organic system also hundred to several thousand times. This soil, populations of mycorrhizal fungi provides an environment more favorable is an example of symbiosis, a win-win as- and their ability to deposit carbon-rich to the spread of the mycorrhizal fungi sociation. “I switched from conventional glomalin in the soil (see below for a and the glomalin they release in the soil. to organic production and used mycor- fuller discussion of glomalin). Other benefits to the proliferation of the rhizal inoculation to help sustain my 4. Mycorrhizal inoculation. Mycor- mycorrhizal fungi have been profound. In yields. What has been interesting is that rhizal activity has been shown to sig- another three-year study of mycorrhizal my fertilizer use has declined dramati- nificantly increase the accumulation of fungi at the Rodale Institute, pepper and cally and my yields have stayed constant, carbon in the soil by depositing gloma- potato yields increased 34 percent and yet the nutritional value of my produce is lin. Glomalin is a compound excreted by 50 percent, respectively, compared to improving.” says Bob Dyer, a large-scale mycorrhizal fungi that adds carbon to controls. Douds’ research suggests that a fruit grower in Mexico and Texas. the soil in vast quantities and improves small amount of mycorrhizal fungi can soil structure. be substituted for a large amount of fer- CARBON-RICH 5. Manure and compost inputs. Ma- tilizer in the growing of crops. ORGANIC SUPER GLUE nure and compost additions to the soil Utilizing the mycorrhizal relationship Mycorrhizal fungi perform another soil provide an organic carbon source; soil on the farm has global implications in the carbon investment service that has only re- organisms over time convert that mate- strategy to increase the carbon content of cently come to light. The USDA published rial to a stable carbon form, humus. soil. Most plants, including more than 90 a report on work by Sara F. Wright and percent of all agricultural crops, form a Kristine A. Nichols that suggests that the THE LINK TO SOIL LIFE root association with these specialized substance glomalin, discovered by Wright The work of another Rodale research fungi. Mycorrhizae literally means “fun- in 1996, is a mechanism for storing large collaborator, Dr. David Douds of the gus roots” and is a symbiotic association, amounts of carbon in soil. Glomalin is USDA Agricultural Research Service, between fungus and plant. Fungal fila- produced by the mycorrhizal fungal group suggests that healthy mycorrhizal fungi ments extend into the soil and help the Glomus, hence the name Glomalin. An populations in the organic systems help plant by gathering water and nutrients organic glue, the glomalin molecule is

Reprinted from October 2008 • Vol. 38, No. 10 made up of 30-40 percent carbon and can tion, organic matter loss and erosion all carbon-building practices such as grow- represent up to an astonishing 30 percent adversely effect beneficial mycorrhizal ing legumes with associated nitrogen- of the carbon in soil. fungi. An extensive body of laboratory fixing bacteria, cover crops, diversified Glomalin acts to bind organic matter testing indicates that the majority of crop rotations inoculated with mycor- to mineral particles in soil. It also forms intensively managed agricultural lands rhizal fungi and other beneficial bacteria, soil clumps — aggregates — that im- lack adequate populations of mycor- and animal manures and compost. prove soil structure and deposit carbon rhizal fungi. High levels of chemical “It’s time to get going,” says Professor on the surface of soil particles. It is glo- fertilizers not only are becoming increas- Dave Perry. “Organic farming is a tried malin that gives soil its tilth — a subtle ingly more expensive, they can also have a and true method that puts carbon in the texture that enables experienced farmers devastating effect on beneficial life in the soil and provides an abundance of ad- to identify rich soil by feeling for the soil. Chemical fertilizers are basically a ditional environmental benefits.” smooth granules as they flow through salt, and as a result they suck the water Unfortunately, in the last 100 years their fingers. Glomalin is a relatively out of beneficial bacteria, fungi, and a we have seen large soil carbon losses stable carbon deposit found in soils, last- wide array of other organisms in the soil. as a result of conventional agricultural ing from seven to 42 years. Mycorrhizal Arden Andersen, both a Ph.D. agrono- practices. Farmers are now appreciat- fungi produce glomalin, apparently to mist and practicing medical physician, ing how important symbiotic soil or- seal themselves and gain enough rigidity states, “Conventional agricultural prac- ganisms and incorporation of carbon to carry materials across the air spaces tices with an emphasis on pumping the sources into the soil were to the farm between soil particles. Wright’s discov- soil with chemical fertilizers can destroy and are now rediscovering these ap- ery of glomalin is causing a complete soil life, which in turn affects the quality proaches as the price of fossil fuels reexamination of what makes up soil and nutritional value of our food.” and chemical fertilizers skyrockets. Ap- organic matter. It is increasingly being Research has shown these beneficial proaches for investing carbon in soils included in studies of carbon storage soil organisms form the basis of the food continue to be refined and improved as and soil quality. web, which conserves and processes nu- we learn to appreciate this diamond in In an earlier study, Wright and sci- trient capital in the soil and promotes the rough for maintaining a productive entists from the University of Califor- soil structure. Without this soil food and profitable farm. nia at Riverside and Stanford University web, a substantial amount of carbon is Mike Amaranthus, Ph.D. is adjunct associate showed that higher CO2 levels in the at- eroded from surface soil, and nutrients professor at Oregon State University and presi- mosphere stimulate the fungi to produce leached from the soil into waterways, dent of Mycorrhizal Applications, Inc., P.O. Box more glomalin. A three-year study was where they damage water quality and 1029, Grants Pass, Oregon 97528, phone 541- done on semi-arid shrub land and a six- aquatic life. By destroying large segments 476-3985, toll-free 866-476-7800, fax 541-476- year study was conducted on grasslands of living soils, a large quantity of car- 1581, e-mail [email protected], website www.mycorrhizae.com. in San Diego County, California, using bon and nutrient capital is lost, and the outdoor chambers with controlled CO2 farmer is forced to add more fertilizer. levels. When CO2 reached 670 parts per The job that should be accomplished by million — the level predicted for our at- beneficial soil organisms must then be mosphere by the mid to late 21st century done by the farmer. — mycorrhizal fungal filaments (hyphae) grew three times as long and produced CONCLUSIONS five times as much glomalin as fungi on For decades after World War II, mas- Acres U.S.A. is the national journal of plants growing with today’s ambient level sive inputs of fossil fuels have allowed sustainable agriculture, standing virtually alone with a real track record — over 35 of 370 ppm. These symbiotic organisms us to partially compensate for topsoil years of continuous publication. Eash may provide a valuable feedback mecha- erosion, organic matter loss and destruc- issue is packed full of information eco- nism to increase soil carbon levels. tion of beneficial soil organisms and es- consultants regularly charge top dollar “Adding carbon to soils is not just sentially cover up poor soil management for. You’ll be kept up-to-date on all of the news that affects agriculture — regu- an inert chemical process, rather it is practices. But the Green Revolution has lations, discoveries, research updates, profoundly influenced by the biologi- turned brown. For three straight de- organic certification issues, and more. cal activity in the soil,” says Jim Trappe, cades, acres of productive farmland have To subscribe, call mycorrhizal researcher and professor declined in the United States and farm emeritus at Oregon State University. input costs are skyrocketing. Taking a 1-800-355-5313 fresh look at managing soils has never (toll-free in the U.S. & Canada) SQUASHING THE SYMBIOSIS made more sense. 512-892-4400 / fax 512-892-4448 Unfortunately, many conventional Many of today’s organic farming prac- P.O. Box 91299 / Austin, TX 78709 agricultural practices reduce or elimi- tices combine methods that increase car- [email protected] nate mycorrhizal activity in the soil. bon contents in the soil. Instead of relying Or subscribe online at: Certain pesticides, chemical fertilizers, on synthetic pesticides and fertilizers, or- www.acresusa.com intensive cultivation, fallow, compac- ganic farming relies on symbiotic and soil

Reprinted from October 2008 • Vol. 38, No. 10