Introduction

There has been a notable ‘climate shift’ in many of the arable regions of eastern, southern and western Australia. A trend to less reliable autumn, winter and spring rainfall has increased production risks for annual cereal crops, while the greater incidence of episodic high intensity rainfall events in summer has heightened the vulnerability of bare fallows to erosion. Declining rainfall experienced over the last 7-10 years has severely impacted on the financial viability of cropping and grazing enterprises and disrupted the social fabric of rural communities.

These events have highlighted a fundamental lack of resilience in current agricultural production systems.

Historical losses of soil and soil carbon

In little over 200 years of European settlement, more than 70 percent of Australian agricultural land has become seriously degraded. Despite efforts to implement ‘ best practice’in soil conservation, the situation continues to deteriorate.

On average, 7 tonnes of topsoil is lost for every tonne of grain produced. This situation has worsened in recent years due to an increased incidence of erosion on unprotected topsoils, coupled with declining yields.

The most meaningful indicator for the health of the land, and the long-term wealth of a nation, is whether soil is being formed or lost. If soil is being lost, so too is the economic and ecological foundation on which production and conservation are based.

In addition to the loss of soil itself, there has been a reduction of between 50% and 80% in the organic carbon content of surface soils in Australia since European settlement (2, 3, 4, 11, 12).

Losses of carbon of this magnitude have immeasurable economic and environmental implications. Soil carbon is the prime determinant of agricultural productivity, landscape function and water quality.

Further, the carbon and water cycles are inextricably linked. Humus holds approximately four times its own weight in water (8). The most beneficial adaptation strategy for climate change would therefore be one that focuses on increasing the levels of both carbon and water in soils.

Discussions on adapting to climate change are irrelevant unless they focus on rebuilding healthy topsoil.

Building new topsoil

Healthy groundcover, active root growth and high levels of microbial association (7), are fundamental to the success of any endeavour to build new topsoil. These factors are absent from conventionally managed broadacre cropland.

Current ’best practice’, that is, chemically-based zero-till broadacre cropping (Fig.1) does not provide a suitable environment for high levels of biological nitrogen fixing, nutrient cycling, hydraulic redistribution, active sequestration of humified soil carbon, or soil building.

 

Fortunately, the highly effective land management technique of ‘perennial cover cropping’ (Figs. 2, 3, and 4) has become more widely adopted in recent years. This practice involves the direct drilling of annual grain or fodder crops into ‘out-of-phase’ dormant perennial groundcover.

The essential first step to rebuilding topsoil is to maximize photosynthetic capacity. A permanent cover of perennial plants provides an ongoing source of soluble carbon for the soil ecosystem, buffers soil temperatures, inhibits weeds, reduces erosion, improves porosity, enhances aggregate stability and water infiltration, slows evaporation, and ‘conditions’ the soil for the production of healthy, high quality, over-sown annual crops.

The soluble carbon exuded into the rhizosphere by perennial groundcover plants and/or transported deep into the soil by mycorrhizal fungi provides energy for the vast array of microbes and soil invertebrates that produce sticky substances enabling soil particles to be glued together into lumps (aggregates). When soil is well aggregated, the spaces (pores) between the aggregates allow the soil to breathe, as well as absorb moisture quickly when it rains. Healthy topsoil should be ‘more space than stuff’, that is, less than 50% solid materials and more than 50% spaces.

Friable, porous topsoils make it easier for plant roots to grow and for small soil invertebrates to move around. Well-structured soils retain the moisture necessary for microbial activity, nutrient cycling, and vigorous plant growth and are less prone to erosion. Soil structure is very fragile and soil aggregates are continually being broken down. An ongoing supply of energy in the form of carbon from the rhizosphere exudates of actively growing plants and, to a lesser extent, decomposing organic materials, enables soil organisms to flourish and produce adequate amounts of the sticky secretions required to maintain soil structure and function.

Healthy, chemical-free soils also create appropriate conditions for humification (conversion of soluble carbon to humus), a process that does not occur in most conventionally managed agricultural soils.

Cropping into dormant perennial groundcover is a one-pass operation that markedly reduces fuel costs and largely eliminates the need for fossil-fuel-based herbicides, fungicides, and pesticides. Perennial cover cropping has many similarities to annual cover cropping but brings with it the ecosystem benefits of perennial groundcover. The practice of perennial cover cropping was inspired by the highly innovative integrated cropping and grazing technique of ‘pasture cropping’ initiated by Darryl Cluff over a decade ago and further developed by Colin Seis (1, 5, 6).

The use of ‘biology friendly’ fertilizers, particularly those based on humic substances, in combination with Yearlong Green Farming (YGF) techniques such as perennial cover cropping, can have a protective effect on soil carbon, slowing or preventing its decomposition and further reducing the carbon footprint of agriculture.

There is no valid reason for the Australian agricultural sector to be a net emitter of CO2.

The world’s soils hold three times as much carbon as the atmosphere and over four times as much carbon as the vegetation. With 82% of terrestrial carbon in soil (compared to only 18% in vegetation), soil represents the largest carbon sink over which we have control. Soil is also the world’s largest store of terrestrial diversity, with over 95% of life forms being underground (that is, only 5% of biodiversity is above ground).

Sequestering humified carbon in soils represents a practical, permanent and productive solution to removing excess CO2 from the atmosphere. By adopting regenerative soil-building practices, it is practical, possible, and profitable for broadacre cropping and grazing enterprises to record net sequestration of carbon in the order of 25 tonnes of CO2 per tonne of product sold (after emissions accounted for).

Australia’s annual emissions of CO2 are predicted to reach 603 million tonnes in 2008.

There are therefore 603 million good reasons for agriculture to be a net sequester of CO2.

It would require only a 0.5% increase in soil carbon on 2% of agricultural land to sequester all Australia’s emissions of carbon dioxide (1). That is, the annual emissions from all industrial, urban, and transport sources could be sequestered in farmland soils if the incentive was provided to landholders for this to happen.

This would provide Australia with a 50-year window of opportunity to be carbon neutral while implementing viable technology to meet future energy needs.

Australian Soil Carbon Accreditation Scheme (ASCAS)

Dr. Christine Jones launched the Australian Soil Carbon Accreditation Scheme (ASCAS) in March 2007. ASCAS is a stand-alone incentive scheme with voluntary involvement, which encourages the adoption of innovative soil building practices (9). Widespread implementation of techniques developed by leading-edge landholders (as depicted in Figs. 2, 3, and 4) will transform the agricultural sector. Adoption of these processes needs to be fast-tracked.

ASCAS is the first incentive payments scheme for soil carbon in the Southern Hemisphere, placing Australia among world leaders in the recognition of soil as a verifiable carbon sink.

Incentive payments for annual measured increases in soil carbon above baseline levels have been sourced from a private donation by Rhonda Willson, Executive Chairman, John While Springs (S) Pte Ltd, Singapore. Receipt of Soil Carbon Incentive Payments (SCIPs) is similar to being paid ‘on delivery’ for livestock or grain, with the bonus being that sequestered carbon remains in the soil, conferring multiple landscape health and productivity advantages. Soil Carbon Incentive Payments are calculated at one-hundredth the 100-year rate ($25/tonne CO2-e).

A 0.5% increase in soil carbon across only 2% of agricultural land would sequester 685 million tonnes of CO2, well above the country’s annual emissions. (Assumptions: 0-30cm soil profile, bulk density 1.4 g/cm3, land area 2% of 445 million hectares).

Annual payments to landholders based on measured soil parameters provide an incentive for maximizing soil carbon sequestration and maintaining the permanency of sinks.

The amount of humified carbon in soil is directly related to nutrient bioavailability, soil structural stability, soil water-holding capacity, agricultural productivity, and landscape function. One of the aims of the ASCAS project is to collect data that will enable rigorous scientific evaluation of soil carbon, water, nutrients, and crop yield under regenerative regimes.

Adapting to climate change

There is an urgent need for Australian agricultural industries to adapt to climate change. To be effective, the strategies employed will require radical departures from ‘business as usual.

It is possible that global warming could accelerate even more rapidly than observed to date. Fundamental redesign of agricultural production systems will enable the sequestration of more carbon and nitrogen than is being emitted, as well as enhancing soil water retention, improving the resilience of the resource base, and restoring richness to farmed soils. These much-needed changes will assist the agricultural sector to deal confidently with a changing climate.

Rather than increase costs, mitigation of climate change via the adoption of regenerative soil building practices would bring net financial benefits to landholders and rural communities (the sectors hardest hit by climate change).

Yearlong Green Farming (YGF) techniques such as perennial cover cropping rapidly build humified soil carbon, improving the capacity of soil to hold water and increasing the resilience of farming systems to climatic extremes.

Farming in a perennial base

A change to farming in a perennial base has many advantages, including

1. same or better yield than chemical fallow or cultivation-style farming

2. fewer inputs, resulting in higher gross margins per hectare

3. less reliance on fossil fuel-based fertilizers and farm chemicals

4. enhancement of natural soil building processes

5. ‘reverse’ carbon footprint – more carbon sequestered than emitted

6. ‘reverse’ nitrogen footprint – more nitrogen fixed than emitted

7. increased water use efficiency due to lower evaporative demand

8. improved soil water balance due to hydraulic lift and hydraulic redistribution

9. no bare soil for weeds to grow – paddocks virtually weed-free

10. reduced financial risk – no expenditure if a crop is not sown

11. an additional income stream from harvest and sale of perennial grass seed

12. more time for family – little or no requirement for cultivation or herbicide application

13. higher biodiversity of plants and animals (eg bettongs returning on some farms)

14. incentive for all members of the farm family, including children, to become involved

The new face of agriculture

Widespread adoption of productive and resilient agricultural practices that enhance net sinks for atmospheric carbon would have a revitalizing effect on the natural resource base and provide a financial benefit to the government, individuals, and rural and regional communities.

Furthermore, farming in a perennial base would enhance the resilience of the agricultural landscape to a wide range of climatic extremes, some of which may not even have been encountered to date.

The development of an appropriate incentives framework for regenerative agricultural activities would reverse the farm sector’s carbon and nitrogen footprints (more C and N sequestered than emitted) and improve food security in a warming, drying environment.

An overview of the Australian Soil Carbon Accreditation Scheme (ASCAS) has been provided as an example of an incentive-based (rather than regulatory) approach. The ASCAS project is an initiative designed to provide proof of concept that: –

1. innovative soil management practices exist for sequestering soil carbon

2. improvements in soil carbon and soil health can be measured

3. landholders can be financially rewarded for building soil carbon

The ASCAS project supports soil restoration by providing financial incentives for landholders to move away from ‘business as usual’ (that is, carbon depleting activities) and by improving community knowledge on effective methods for building soil carbon.

Irrespective of climate change, it would be of enormous economic benefit to the agricultural sector to rebuild soils by implementing practices that increase levels of humified soil carbon and reduce reliance on fossil fuels.

In 1937, Franklin Roosevelt (10) stated “The nation that destroys its soil destroys itself”. The future of Australia depends on the future of our soil.

REFERENCES CITED

Thank you all for your support in 2022 and Merry Christmas. 

If you are looking to spoil yourself or a green thumb for Christmas consider some MycoGold  https://biostim.com.au/shop/myco-gold/

Phosphate fertiliser prices are once again extreme. This effects super phosphate, single super, triple super, MAP, DAP, MKP, etc pricing and availability. Supply and demand determines prices but these increases are mainly on the supply side. The war in Ukraine has caused sanctions on Russia further limiting the number of suppliers in the world market. Morocco basically controls the world price as the world has under invested for decades in developing phosphate mines.

The ABC just did a video below but I have a few issues with the reporting.

1/ Australian soils have large reserves of phosphate but they are often in plant unavailable forms.

2/ Using tax player funding to build infrastructure isn’t moral or wise as the price will correct at some stage and we are a high cost producer.

3/ Rock phosphate may never become plant available. You need extensive microbial activity (labile carbon and moisture) and/or low soil pH to release the phosphate. Applying to dead soil is a total waste of resources/capital.

A more sustainable solution that requires no tax payer funding is mycorrhizal fungi as that can help unlock existing phosphate reserves. Even better than mycorrhizal fungi is implementing a cover crop strategy if possible.

They say if you apply heat and pressure to coal underground over time you can change it into a diamond, but farmers are trying to develop their own gem beneath the soil surface. Coal is basically a fossilized lump of soil carbon: ancient plant and animal remains that we liberate to release energy. Today, the estimated amount of carbon stored in world soils is about 1,100 to 1,600 petagrams (one petagram is one billion metric tons), more than twice the carbon in living vegetation (560 petagrams) or in the atmosphere (750 petagrams).

Unfortunately, however, on agricultural lands, soil carbon has been lost at an alarming rate. Carbon in the soil, in the form of organic matter, stable humus or glomalin, can be a “diamond in the rough” for farmers due to the important role it plays in both the productivity and profitability of the farm. Considering the skyrocketing costs of conventional farm inputs, growers are rapidly learning the most effective ways to get carbon back into the soil in order to maintain productivity.

HOW THE SYSTEM WORKS

Carbon input in soils occurs almost primarily via plant production. Plants convert carbon dioxide into tissue and other compounds through photosynthesis. Much of these compounds are allocated to root systems below the soil surface or to fuel the activities of beneficial soil organisms such as mycorrhizal fungi. As plants, roots, and mycorrhizal threads in the soil die, they are decomposed, primarily by soil microorganisms. Through this process, some of the carbon is stored in the soil and some is released through respiration back to the atmosphere as carbon dioxide. Examples of stable soil organic materials are called humus and glomalin.

These residues can persist in soils for decades, hundreds, or even thousands of years. The humus and glomalin compounds mentioned above are the dark black content of a healthy soil — black due to the carbon content itself. They are critical for the soil’s biological activity, productivity, and profitability. This “bankroll” of stored energy is truly a gem when it comes to sustainable agriculture.

OUT OF SIGHT, OUT OF MIND

Leonardo da Vinci once said, “We know more about the movement of the celestial bodies than the soil underfoot.” Soil still remains a great mystery. In today’s high-tech society most people keep soil out of mind and out of context — yet what could be more important? All living things originate from the soil and eventually return to it. All great civilizations, including the Egyptians, Greeks, Mayans, and Romans, depended upon an adequate supply of fertile soil. These civilizations also declined when soil resources became thin due to erosion and bad management.

Throughout history, the story has repeated itself. Great civilizations have flourished where soils were fertile enough to support high-density human communities and fell when soils could no longer sustain the demands put on them. The great early civilizations of Mesopotamia arose because of the richness of their soils and collapsed because of declines in soil quality. Poor land management, organic matter loss, and excessive irrigation caused soils to become increasingly degraded, leading to power struggles, migrations, and ultimately the collapse of the Fertile Crescent civilizations.

Ancient Greece suffered a similar fate. The philosopher Plato, writing around 360 B.C., attributed the demise of Greek power to land degradation: “[In earlier days] Attica yielded far more abundant produce. In a comparison of what then was, there are remaining only the bones of the wasted body; all the richer and softer parts of the soil having fallen away, and the mere skeleton of the land being left.” Plato’s reference to “lighter and softer” was likely referring to organic matter content of the soil.

Many experts also blame the collapse of the great Mayan civilization on soil exhaustion and erosion, resulting from agricultural practices and vegetation removal. According to Jared Diamond, a UCLA professor and author of Guns, Germs, and Steel and Collapse, 90 percent of the people inhabiting Easter Island in the Pacific died because of deforestation, erosion, and soil depletion. In Iceland, farming and human activities caused the majority of the soil to end up in the sea, explains Diamond. “Icelandic society survived only through a drastically lower standard of living,” he says.

These lessons of the past unfortunately do not seem to resonate in the modern world. Today, we don’t think much about the ground beneath our feet that supports our farms, cities and societies. Yet all of us intrinsically know that good soil is just not dirt. When you dig into rich, fresh earth, you can literally feel the life in it. Fertile, living soil is chocolate brown and falls off your trowel and crumbles into small pieces in your hand. It is light and easy and has an enticing aroma. It is the smell of life itself. The ability to recognize good soil allowed our ancestors to survive and thrive for generations, and it is the carbon content of the soil that identifies this important resource.

Carbon Sequestration: Amazing Numbers

The Rodale Institute, researchers at Cornell University, and the Agricultural Research Service have collaborated to develop estimates of carbon sequestration in soils by implementing organic farming methods. When we apply these numbers to U.S. agriculture, some compelling insights emerge. The bottom line is that U.S. agricultural lands, compared to other types of lands, provide a tremendous opportunity to store carbon in soils (see table, below).

U.S. agriculture currently releases 750 million tons of CO2 annually into the atmosphere. Converting all U.S. agricultural lands to organic production would eliminate agriculture’s massive emission problem. In addition, switching to organic production would actually result in a net sequestering of 811 million tons of CO2 per year.

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 much carbon in the soil that it would be equivalent to taking 1,174,400 cars off the road or reducing car miles driven by 14.62 billion miles.

TAKING IT TO THE BANK

Carbon compounds in the soil is an investment that could easily be compared to the workings of a modern-day bank. Deposits and withdrawals are made by the natural rhythm of root and mycorrhizal activity, decay, and recycling. This bank has been our central “financial institution,” sustaining the human race for millennia, although there have been numerous times in our history, in large geographical areas, where withdrawals have exceeded deposits — resulting in biological bankruptcy.

Carbon compounds in soil enhance plant growth directly through both physiological and nutritional effects. Carbon compounds improve root and mycorrhizal development, uptake of plant nutrients, and serve as a source of nitrogen, phosphorus, and sulfur. Indirectly, carbon compounds also affect plant growth through modifications of physical, chemical, and biological properties of the soil, including an increase in water-holding capacity, the ability to retain nutrients, and improvement of tilth and aeration through good soil structure.

In the last century, soil carbon has been lost at a staggering rate due to excessive tillage, erosion, and the use of chemical fertilizers. In temperate regions, for example, half of the soil organic matter commonly disappears after a few decades of tillage. In tropical soils, such losses can occur in under a decade.

CARBON & ORGANIC FARMING

For years, many have argued that organically produced food is safer and more nutritious. Now we are learning that a switch to organic production methods is an expedient and soil-based sink for reducing carbon from the atmosphere. Data from the Rodale Institute’s long-term comparison of organic and conventional farming methods substantiates that organic practices are much more effective at removing carbon dioxide, a major greenhouse gas, from the atmosphere 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 mycorrhizal 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 manures can dramatically alter the C storage 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 Rothamsted in the United Kingdom from 1843 to 1975 showed that areas treated with manure for more than 100 years nearly tripled in soil nitrogen content compared to adding nitrogen as a chemical fertilizer. In the areas where chemical fertilizer was used, nitrogen was either lost in soil runoff or exported with the crop.

Additionally, a 15 year, the side-by-side study of corn and soybeans at the Rodale Institute in Pennsylvania, showed no difference in crop yields where legumes and manures were used instead of synthetic fertilizers and pesticides. Organic and conventional cropping systems produced similar profits and the soil carbon content for the organic plots increased three to five times.

FRESH DATA FROM AN OLD EXPERIMENT

Since 1981, the Rodale Institute Farming Systems Trial (FST) has continuously compared conventional and organic farming in side-by-side trials. This research provides a wealth of information about the ecological and economic benefits of organic farming that includes detailed studies of cultivation, fertilizer, mycorrhizal fungi, weeds, compost, cover crops, water quality, and profitability. The study contains convincing evidence that organic farming incorporates significant amounts of carbon into the soil, compared to conventional farming.

The key to this process lies in the handling of soil organic matter. Because soil organic matter is primarily carbon, increased levels of carbon directly correlate with carbon sequestration. While conventional farming practices typically deplete soil organic matter, organic farming builds it through the use of composted animal manures, cover crops, legumes, and the activities of symbiotic mycorrhizal fungi and bacteria.

“Good organic farmers see carbon as a resource that improves crop quality, soil productivity, and yield rather than carbon as a waste product,” says Gerald Wiebe, an organic farmer in Manitoba, Canada. Wiebe sees the value of active management of the biological component in the soil to encourage carbon storage in soil. “Some organic farmers tend to use a zero-input approach to organic farming, thinking that sunshine, seed, and rain are all they need. This often leads to decreased yields with no improvement in soil conditions. The simple non-use of conventional inputs does not guarantee that soil microbial life, carbon levels, and soil structure will be restored. However, when mycorrhizal and bacterial inoculants, compost, compost tea, green manures, legumes, etc., are used in a well-managed program, positive soil changes happen relatively quickly.”

The FST is a long-term experiment comparing three agricultural management systems: one conventional, one legume-based organic, and one manure-based organic. The FST’s two organic systems have shown an increase of 15-28 percent in soil carbon, while the conventional system has shown no statistically significant increase. In organic systems, that converts to more than 1,000 pounds of captured C (or about 3,670 pounds of CO2) per acre-foot per year.

Organic Material, Organic Matter & Soil Carbon

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 and think, “Wow! I’m adding a lot of organic matter to the soil.” This soil amendment is actually organic material, not organic matter.

What’s the difference between organic material and organic matter? Organic material is anything that was alive and is now in or on the soil. For it to become organic matter, it must be decomposed into humus. Humus is organic matter that has been converted by microorganisms to a resistant state of decomposition. Humus is approximately 50 percent carbon and 5 percent nitrogen.

Organic matter is stable in the soil. It has been decomposed until it is resistant to further decomposition. Usually, only about 5 percent of organic matter mineralizes yearly. That rate increases if temperature, oxygen, and moisture conditions become favorable for decomposition, which often occurs with soil tillage. It is the stable organic matter that is analyzed in soil tests. Organic material is unstable in the soil, changing form and mass readily as it decomposes. As much as 90 percent of it disappears quickly because of decomposition.

Organic Matter & Carbon in Our Soils

An acre of soil measured to a depth of one foot weighs approximately 4 million pounds, which means that 1 percent organic matter in the soil would weigh about 40,000 pounds per acre and contain roughly 20,000 pounds of carbon. Since it takes at least 10 pounds of organic material to decompose 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 stable organic matter (40,000 pounds) under favorable conditions.

How much has been lost? Research indicates that organic matter content in the prairie regions of the United States and Canada has declined between 50 and 90 percent since the land was first cultivated. Let’s look at an example. Due to organic matter converting to carbon dioxide, the organic matter in a top foot of soil on a conventionally managed Iowa cornfield has decreased from 10 percent to 5 percent. How much soil carbon has been lost? How much CO2 has been released into the atmosphere? A reduction of 5 percent organic matter equals 50 tons of soil carbon (100,000 pounds) lost to the atmosphere. When oxidized, this 50 tons of carbon is equivalent to over 180 tons of atmospheric carbon dioxide released from a single acre! There are millions of acres of farmland in the United States that have seen at least a 5 percent decline in total soil organic matter content due to conventional farming practices.

THE 5-STEP PROGRAM TO RECOVERY

How do we stop burning up our soil’s organic matter to produce food? How do we conserve and increase soil organic matter? Following five basic steps can make the difference between storing or releasing carbon in our soils.

1. Grasses and legumes. The periodic use of grasses, grass legumes, or legumes in a crop rotation can add large amounts of organic matter to the soil.

2. Continuous cover. This method keeps plants pumping soil with carbon year-round and supports the sequestering activities of beneficial soil organisms such as mycorrhizal fungi. The results are soil organic matter at higher levels than fallow-cropping systems.

3. Conservation tillage. No-till or minimum tillage reduces organic matter decomposition and release of carbon from the surface soil. In the process, it also increases the physical structure of the soil, populations of mycorrhizal fungi, and their ability to deposit carbon-rich glomalin in the soil (see below for a fuller discussion of glomalin).

4. Mycorrhizal inoculation. Mycorrhizal activity has been shown to significantly increase the accumulation of carbon in the soil by depositing glomalin. Glomalin is a compound excreted by mycorrhizal fungi that adds carbon to the soil in vast quantities and improves soil structure.

5. Manure and compost inputs. Manure and compost additions to the soil provide an organic carbon source; soil organisms over time convert that material to a stable carbon form, humus.

THE LINK TO SOIL LIFE

The work of another Rodale research collaborator, Dr. David Douds of the USDA Agricultural Research Service, suggests that healthy mycorrhizal fungi populations in the organic systems help deposit carbon in the soil. In the FST, soils farmed with organic systems have greater populations of mycorrhizal fungi. Overwintering cover crops supply energy to fuel the activities of mycorrhizal fungi in the organic system, in contrast to the conventional systems, which have a significantly greater fallow period. Reduced chemical use in the organic system also provides an environment more favorable to the spread of the mycorrhizal fungi and the glomalin they release in the soil. Other benefits to the proliferation of the mycorrhizal fungi have been profound. In another three-year study of mycorrhizal fungi at the Rodale Institute, pepper and potato yields increased 34 percent and 50 percent, respectively, compared to controls. Douds’ research suggests that a small number of mycorrhizal fungi can be substituted for a large amount of fertilizer in the growing of crops.

Utilizing the mycorrhizal relationship on the farm has global implications in the strategy to increase the carbon content of the soil. Most plants, including more than 90 percent of all agricultural crops, form a root association with these specialized fungi. Mycorrhizae literally mean “fungus roots” and is a symbiotic association, between fungus and plant. Fungal filaments extend into the soil and help the plant by gathering water and nutrients and transporting these materials back to the roots. In exchange, the plant supplies sugar and other compounds to fuel the activities of the fungus. Miles of fungal filaments can be present in an ounce of healthy soil. The crop’s association with mycorrhizal fungi increases the effective surface absorbing area of roots several hundred to several thousand times. This is an example of symbiosis, a win-win association. “I switched from conventional to organic production and used mycorrhizal inoculation to help sustain my yields. What has been interesting is that my fertilizer use has declined dramatically and my yields have stayed constant, yet the nutritional value of my produce is improving,” says Bob Dyer, a large-scale fruit grower in Mexico and Texas.

CARBON-RICH ORGANIC SUPER GLUE

Mycorrhizal fungi perform another soil carbon investment service that has only recently come to light. The USDA published a report on work by Sara F. Wright and Kristine A. Nichols that suggests that the substance glomalin, discovered by Wright in 1996, is a mechanism for storing large amounts of carbon in the soil. Glomalin is produced by the mycorrhizal fungal group Glomus, hence the name Glomalin. An organic glue, the glomalin molecule is made up of 30-40 percent carbon and can represent up to an astonishing 30 percent of the carbon in the soil.

Glomalin acts to bind organic matter to mineral particles in the soil. It also forms soil clumps — aggregates — that improve soil structure and deposit carbon on the surface of soil particles. It is glomalin that gives soil its tilth — a subtle texture that enables experienced farmers to identify rich soil by feeling for the smooth granules as they flow through their fingers. Glomalin is a relatively stable carbon deposit found in soils, lasting from seven to 42 years. Mycorrhizal fungi produce glomalin, apparently to seal themselves and gain enough rigidity to carry materials across the air spaces between soil particles. Wright’s discovery of glomalin is causing a complete reexamination of what makes up soil organic matter. It is increasingly being included in studies of carbon storage and soil quality.

In an earlier study, Wright and scientists from the University of California at Riverside and Stanford University showed that higher CO2 levels in the atmosphere stimulate the fungi to produce more glomalin. A three-year study was done on semi-arid shrubland and a six-year study was conducted on grasslands in San Diego County, California, using outdoor chambers with controlled CO2 levels. When CO2 reached 670 parts per million — the level predicted for our atmosphere by the mid to late 21st century — mycorrhizal fungal filaments (hyphae) grew three times as long and produced five times as much glomalin as fungi on plants growing with today’s ambient level of 370 ppm. These symbiotic organisms may provide a valuable feedback mechanism to increase soil carbon levels.

“Adding carbon to soils is not just an inert chemical process, rather it is profoundly influenced by the biological activity in the soil,” says Jim Trappe, mycorrhizal researcher and professor emeritus at Oregon State University.

SQUASHING THE SYMBIOSIS

Unfortunately, many conventional agricultural practices reduce or eliminate mycorrhizal activity in the soil. Certain pesticides, chemical fertilizers, intensive cultivation, fallow, compaction, organic matter loss, and erosion all adversely affect beneficial mycorrhizal fungi. An extensive body of laboratory testing indicates that the majority of intensively managed agricultural lands lack adequate populations of mycorrhizal fungi. High levels of chemical fertilizers not only are becoming increasingly more expensive, they can also have a devastating effect on beneficial life in the soil. Chemical fertilizers are basically salt, and as a result, they suck the water out of beneficial bacteria, fungi, and a wide array of other organisms in the soil. Arden Andersen, both a Ph.D. agronomist and practicing medical physician, states, “Conventional agricultural practices with an emphasis on pumping the soil with chemical fertilizers can destroy soil life, which in turn affects the quality and nutritional value of our food.”

Research has shown these beneficial soil organisms form the basis of the food web, which conserves and processes nutrient capital in the soil and promotes soil structure. Without this soil food web, a substantial amount of carbon is eroded from surface soil, and nutrients leached from the soil into waterways, where they damage water quality and aquatic life. By destroying large segments of living soils, a large quantity of carbon and nutrient capital is lost, and the farmer is forced to add more fertilizer. The job that should be accomplished by beneficial soil organisms must then be done by the farmer.

CONCLUSIONS

For decades after World War II, massive inputs of fossil fuels have allowed us to partially compensate for topsoil erosion, organic matter loss, and destruction of beneficial soil organisms and essentially cover up poor soil management practices. But the Green Revolution has turned brown. For three straight decades, acres of productive farmland have declined in the United States and farm input costs are skyrocketing. Taking a fresh look at managing soils has never made more sense.

Many of today’s organic farming practices combine methods that increase carbon contents in the soil. Instead of relying on synthetic pesticides and fertilizers, organic farming relies on symbiotic and soil carbon-building practices such as growing legumes with associated nitrogen-fixing bacteria, covering crops, diversified crop rotations inoculated with mycorrhizal fungi and other beneficial bacteria, and animal manures and compost.

“It’s time to get going,” says Professor Dave Perry. “Organic farming is a tried and true method that puts carbon in the soil and provides an abundance of additional environmental benefits.”

Unfortunately, in the last 100 years, we have seen large soil carbon losses as a result of conventional agricultural practices. Farmers are now appreciating how important symbiotic soil organisms and the incorporation of carbon sources into the soil were to the farm and are now rediscovering these approaches as the price of fossil fuels and chemical fertilizers skyrockets. Approaches for investing carbon in soils continue to be refined and improved as we learn to appreciate this diamond in the rough for maintaining a productive and profitable farm.

The ancient Romans had a legend about a malicious boy who tormented a fox by tying wheat straw to its tail and then setting the straw on fire. The Roman god of crop protection, Robigus, was so irritated that he penalized humanity with wheat rust, the fungal disease that leaves a farmer’s field looking as though it has been burned. For hundreds of years afterward, the Romans sought to pacify Robigus by sacrificing dogs or cows with the misfortune of being born with rust-colored fur.

Modern farmers make sacrifices overcrop diseases, too. Often profits are sacrificed to prevent damage from a host of fungal rascals with names such as black rot, clubroot, sclerotina blight, wire stem, sudden death syndrome, brown spot, charcoal rot, and head blight. Not all fungal players are destructive, though — opportunities also exist to harness beneficial fungi as remedies for these costly agricultural rascals. The many well-documented benefits of mycorrhizal fungi include improving crop nutrients, water uptake, carbon content, and soil structure. These fungi can also improve crop yields and decrease costs for fertilizer and water.

THE FUNGUS RASCAL

Robigus, the god that brought us fungus, can be a rascal with a real appetite. While urban dwellers fear common maladies such as itchy toes and moldy bread, farmers face far more serious fungal diseases that can inflict widespread damage on a farm. For example, scientists estimated soybean disease losses for the 1994 crop from 10 countries with the greatest soybean production. The total loss of yield due to disease was 14.99 million metric tons, valued at a whopping $3.31 billion.

Certain Fusarium fungal species are among the most dangerous cereal crop diseases in the world, with a dramatic increase of infection witnessed in the early 1990s. The ability of this disease to form toxins poisonous to both humans and animals makes it a serious problem.

Another disease, damping-off, caused by Pythium and Rhizoctonia fungi, affects agricultural seedlings growing in flats or in the farmer’s field. The damping-off disease attacks young seedlings just prior to their emergence or topples them a few days afterward. When older seedlings are attacked by Rhizoctonia, the lower stem becomes constricted, turning dark-brown near the soil surface, a symptom called wire-stem. Affected plants may die when stressed, break in strong winds, or produce a stunted, unmarketable crop. David Weller, a research leader with the USDA’s Agricultural Research Service, characterizes this condition as “a tremendous challenge.

Weller estimates that in the Pacific Northwest, a complex of root diseases including Rhizoctonia, Fusarium, and Pythium routinely steals 10 to 15 percent of conventionally grown wheat and barley yields. In direct-seeding crop systems, losses can exceed 50 percent.

Phytophthora, the notorious root disease that caused the Irish potato famine, today remains the cause of annual crop losses amounting to tens of billions of dollars. Beginning in 1845, the six-year potato famine killed over a million men, women, and children in Ireland and forced another million to flee the country. Phytophthora — from the Greek phytón, “plant” and phthorá, “destruction” — translates literally to “the plant destroyer” and continues to plague a wide variety of crops globally without an effective means of chemical control.

THE FUNGUS REMEDY

We can never purge the world of fungi, of course, nor would we want to, for within this world also reside the very remedies for the rascals. In the taxonomic hierarchy, the kingdom is the highest echelon. There are five kingdoms among all living organisms, and our fungal friends represent one kingdom unto themselves. The others are animals, plants, bacteria, and protists. Scientists have described some 100,000 species of fungi, and experts estimate that over a million remain to be discovered.

Fungi have influenced our lives in ways we often take for granted. We can thank the fungus Saccharomyces, known as baker’s and brewer’s yeast, for that loaf of bread and jug of wine. When recovering from an infection, we can frequently thank the common soil fungus Penicillium. When Alexander Fleming discovered penicillin, he was trying to perfect an antiseptic formula based on nasal mucus. The nasal mucus formulation never did materialize (we can all breathe a sigh of relief!), but his unforeseen discovery of antibiotics changed the world (not entirely for the better, as it later turned out).

Fungi also have a flair for symbiosis — the ability to establish cross-kingdom relationships in which they are fed plant-produced sugars in exchange for bestowing their partners with new powers. Under natural conditions, plants live in close symbiotic association with a group of soil organisms called mycorrhizal fungi.

These fungi colonize plant roots, essentially extending the root system into the surrounding soil. The quantity of mycorrhizal filaments present in soil associated with host plants is astonishing. It is estimated that several miles of these filaments can be present in less than a thimbleful of soil. The relationship is beneficial because the plant enjoys improved nutrient and water uptake, and superior survival and growth.

It is this humble but critical association between plants and mycorrhizal fungi that keeps the whole show rolling in natural environments. Approximately 90 percent of all land plants depend on the mycorrhizal fungi radiating from their roots and feeding modestly on their plant sugars. In return, the fungus delivers essential nutrients from the soil such as phosphorus, calcium, nitrogen, and life-giving water. Botanists believe that plants might never have made the evolutionary leap onto land some 460 million years ago without the godly assist of Robigus and his mycorrhizal assistants.

These mycorrhizal fungi are among the most researched and best understood of the soil microbe families — and are potentially the most useful to agriculture. Most important agricultural crops form the mycorrhizal relationship (with notable exceptions of the mustard family, canola, broccoli, and sugar beets). Mycorrhizae attach themselves to plant roots and grow thread-like hyphae out into the surrounding soil, siphoning nutrient molecules and water back to the plant. A crop benefits from mycorrhizal inoculation by increasing the efficiency and utilization of added fertilizer and water.

Dr. Alok Adholeya, Director of Biotechnology from the Energy and Resource Institute in India, demonstrated in replicated studies that mycorrhizal inoculations at sowing resulted in a savings of 30 percent in fertilizer requirement. Significant fertilizer savings were achieved for important crops in the region such as potato, onion, pepper, garlic, and strawberry.

Long fallows, heavy tillage, and certain agricultural chemicals are known to kill or suppress mycorrhizae and other soil life. To overcome the damage to the “soil food web” that naturally creates and stores soil fertility, many conventionally grown crops receive an excess of inorganic chemical fertilizers. The ever-escalating costs of these chemical inputs, many of which depend upon fossil fuels, are cutting deeply into conventional farming profits.

CARBON SINK

Perhaps the most significant part of this plant-fungal interaction is the protective, carbon-rich sheath that forms around the hyphae of arbuscular mycorrhizae. The sheath is made of glomalin, a substance only recently identified (in 1996). Glomalin is 30-40 percent carbon, which researchers think may account for much of the carbon stored infertile soils. Not only is it critical for carbon storage, but the higher the levels of glomalin found in a soil, the better its tilth (its desirable feel and structure), the less its susceptibility to wind or water erosion, and the better it seems to grow plants. This is particularly true in the Northern Plains region of the United States, where rangeland covers 43 percent of the landscape. More than 60 percent of these soils are highly vulnerable to wind erosion, which destroys soil and releases carbon dioxide into the atmosphere.

Studies on cropland and rangelands indicate that both tillage and fallowing — as is common in arid regions such as those in the Northern Plains — lower glomalin levels by destroying living hyphal networks. The networks are physically torn by tillage or are destroyed due to starvation during fallowing. However, this glomalin loss can be reversed. A greenhouse trial in Oregon found that mycorrhizal inoculation of tall fescue nearly doubled a soil’s rate of carbon increase in a year and that glomalin correlated significantly with the increase. Furthermore, glomalin resists breakdown for seven to 42 years, making it long-term carbon storage.

FUNGAL STOMACHS

The defining personality of a fungus is gustatory. Whereas animals consume a meal first and then digest it internally, fungi do the opposite. After encountering a suitable food source, they release enzymes to break down the substance into a soupy mash of sugars and amino acids, dislodging nutrients that they can then absorb through the membranes of their filamentous hyphae. In a process similar to the way our own stomachs produce enzymes to digest food, mycorrhizal fungi release powerful enzymes into the soil that dissolve and capture otherwise elusive nutrients such as phosphorus, calcium, iron, and other “tightly bound” soil nutrients.

This extraction process is particularly important in plant nutrition, explaining why non-mycorrhizal crops often require high levels of fertility to maintain productivity. By forming an intricate web that captures and assimilates nutrients, mycorrhizal fungi conserve the nutrient capital in soils. In nonmycorrhizal conditions, much of this fertility is wasted or lost from agricultural lands. Mycorrhizal fungi increase nutrient uptake not only by increasing the surface absorbing area of roots but also by acting as a “stomach,” digesting much-needed plant nutrients.

CONCLUSION

Fungi are omnipresent, occupying every ocean, our atmosphere, and Earth’s every landmass. It is true that some rascal fungi are “killers,” infesting and attacking living tissue, but the vast majority of fungi are benevolent, and in many cases, vital to the life forms around them. As we have seen, fungi can be both rascals and remedies to the farmer. While fungal diseases might impact the bottom line, mycorrhizal fungi can improve farm yields. Certainly, we can agree that recruiting the help of beneficial fungi on the farm is a preferred alternative to sacrificing rust-colored dogs and cows to Robigus.

Understanding Native Soils

How do soils function in their natural condition? How do native grasslands and forests produce an abundance of plants and animals in the complete absence o irrigation, fertilizer, and tillage? The answer lies in understanding certain principles by which native soils function. We have been taught that soils are comprised o four basic components: minerals, air, water, and decaying organic matter. What we haven’t been told is that there is another major component of soil. It is the web of life, the “living soil” that supports plant health and growth (figure 2). Take a look at the amount of soil organisms present in an acre of healthy topsoil:

• 1000 pounds of earthworms
• 1500 pounds of bacteria
• 900 pounds of arthropods
• 130 pounds of protozoa
• 1000 pounds of actinomycetes
• 2500 pounds of fungi
• Thousands of miles of mycorrhizal fungal filaments.

The living oil can help farmers develop and maintain productive and profitable soil conditions for today and or future generations. Dr. Arden Andersen, a physician and leader in the field of sustainable agriculture says, “The health of the living oil effects the health of the crop and ultimately humans. Using sustainable technologies, such as mycorrhizal fungi which work with nature and outperforms conventional agriculture” (figure 3).

When the soil is healthy, alive, and managed in a sustainable manner, several positive features emerge:

*Reliance on expensive additives declines.

* Land value increases * Income potential increases.

* Natural processes can replace artificial intervention.

The Real Dirt

The living soil, the “real dirt” should be viewed as a living community and, not an inert body. What do beneficial soil organisms do in natural areas that can also benefit the farm? Native prairies and forests functioned for decades and centuries without artificial inputs. The soils are tilled by soil organisms, not by machinery. They are fertilized too, microscopic bacteria fix nitrogen from the atmosphere and convert it to a form readily available to plants. In the natural soil system, fertility is used over and over again and nutrients are not lost to runoff, groundwater, or erosion. Jim Trappe, Ph.D. professor at Oregon State University has studied living oil for 45 years and published over 250 scientific papers on the subject. Says Jim, Beneficial soil organisms such as mycorrhizal fungi conserve, process and transport bound up minerals directly to the pants via a microscope web of fungal filaments. The original “world wide web” of mycorrhizal filaments beneath the soil surface will work for the farmer’s benefit if simply managed for their survival”. There are over 50,000 thousand scientific studies on mycorrhizal fungi.

What Are Mycorrhizal Fungi?

“Mycor” – “rhiza” literally means “Fungus” – “root” and defines the mutually beneficial relationship between the plant root and fungus. These specialized soil lung colonizes plant roots and extends far into the soil resource. Mycorrhizal fungal filaments in the soil are truly extensions of root systems and more are effective in nutrient and water absorption ions than the roots themselves. A thimble full of healthy soil can contain several miles of fungal filaments that direct soil resources back to the plant roots.

Nearly all agriculturally important plants form endomycorrhizal. Here is a list of some commercially important agricultural plants that research has shown benefit from endo mycorrhizae:

Endomycorrhizal fungi penetrate into and around root cells and form specialized cells in the roots for the storage and transfer of materials between the plant and fungus. Endomycorrhizal species form individual spores which are the “seeds” that form the next colony of the mycorrhizal fungi (figure 4). These spores are formed beneath the soil surface and do not readily disperse and colonize an area once they have been lost from a site.

Over the past 400 million years, this association of mycorrhizae with the plant has evolved to a level where, in addition to sourcing food and moisture, the mycorrhiza has taken on other properties that assure plant health and vigor. As the fungi infect or colonize spots along with the root system, it restricts access to various organisms. The thousands of miles of mycorrhizal filament resent in an acre of healthy soil provides access to water or act as miners, excreting specific enzymes, converting tightly bound nutrients such as phosphorous from mineral soils into forms that can be used by plants.

Specific Benefits

Mycorrhizal fungi are the most researched aspect of the living soil. Mycorrhizal fungi can produce increased growth because they improve the absorption of soil phosphorus, zinc,  iron,  calcium,  magnesium,  manganese, and sulfur.  Research indicates mycorrhizal colonization increases a crop’s ability to absorb water from the soil and withstand extended periods of drought. Improved photosynthesis capacity resulting from colonization has also been cited in reducing the negative effects of salt and toxic elements. Mycorrhizae can also produce synergistic effects in legume crops when the inoculants of fungi and nitrogen-fixing bacteria are combined.

Soil And Mycorrhizal Fungi

A soil that drains well does not crust and takes in water and oxygen is said to have good tilth. Soil tilth influences the ease of tillage, root penetration, and seedling emergence. Soil with good tilth is said to be well-aggregated. Well-aggregated conditions occur when individual soil particles are joined together in stable clusters that improve the infiltration and porosity of the soil. USDA oil microbiologist Sara Wright named the glue that holds aggregates together “glomalin” after the common Glomales group of the endomycorrhizal fungi that live with the most agricultural crops. These mycorrhizal fungi secrete this gooey protein with their tiny filaments. This sticky glue holds individual soil particles in water-stable aggregates that encourage the flow of both moisture and oxygen through the root zone. Glomalin levels are high in healthy well-aggregated soils. Figure 5 is a picture of healthy well-aggregated soil.

Does My Soil Already Contain Mycorrhizal Fungi?

Mycorrhizal fungi are present in most undisturbed soil ecosystems, along with innumerable amounts of bacteria, protozoa, actinomycetes, worms, insects, etc. Mycorrhizal populations are particularly low, and many times nonexistent, in agricultural soils that have been altered by certain pesticides, chemical fertilizers, tillage, compaction, organic matter loss, erosion, and fallow periods. Once lost from a farm, endomycorrhizal populations are slow to recolonize. Endomycorrhizal fungi form their spores or”seeds” below the soil surface. Because these spores do not readily move in the air, they do not move long distances from natural areas back to the farm.

Nursery-grown crop plants available to farmers are often deficient in mycorrhizae. Plants raised in most nurseries receive intensive care and feeding. These artificial conditions, such as high levels of water, nutrients, and sterile soil-less mixes at the nursery produce large quantities of plants for sale. Unfortunately, the high levels of water and nutrients and the lack of mycorrhizae discourage the plant from producing the extensive root system it will need for successful transplantation. Thus these plants are poorly adapted to the eventual out-planted condition and must be weaned from intensive care systems and begin to fend for themselves. Applicant on of mycorrhizal inoculum before, or during, transplantation can encourage plant establishment and set the plant on track to feed for itself. Research studies document the need for plants to generate a mycorrhizal roots system in order to quickly become established.

Mycorrhizal colonization can also be reduced by high rates of available phosphorous. Studies have documented a decline in mycorrhizal colonization when available P rates exceed 80 ppm. On many farms, there is an adequate supply of soil phosphorous but it is tied up in the soil and not available to plants. Mycorrhizal fungi such as Glomus mosseae, Glomus intraradices and Glomus etunicatum species produce a high level of phosphatase enzymes that specifically extract tightly bound phosphorous from clay particles and make P immediately available to the plant. Since mycorrhizal fungi are important to accessing P in soil, a healthy mycorrhizal population eliminates the need for high levels of P fertilization. Some scientific studies have shown that following mycorrhizal inoculation growers can decrease their P fertilization by 20-30 percent without any loss of plant productivity. In fact, most studies have documented large increases in P uptake when mycorrhiza is present. This has a significant impact on to agricultural production because phosphorous is second only to nitrogen in terms of its importance to crop growth and development.

While some fungicides reduce or eliminate mycorrhizal fungi other research indicates that certain types of fungicides do not adversely affect mycorrhizae. A list of fungicides and their effects on mycorrhizae can be accessed www.biostim.com.au. In addition, mycorrhizal inoculants can be used for 4 to 6 weeks before applying fungicides allowing the mycorrhizae to firmly establish within the plant root. Mycorrhizal inoculum can also be added following the use of a fungicide. Follow the manufacturers’ guidelines for the time in which the fungicide “clears” the soil media.

How To Use Mycorrhizal Fungi?

Agricultural markets are already benefiting from the use of mycorrhizal inoculum and use has increased dramatically in recent years. New developments in the growing of mycorrhizal inoculum have made using mycorrhizae on the farm more cost-effective, easy, and affordable. High quality, concentrated mycorrhizal inoculum containing diverse species is the best choice. Because of the wide variety of crops, soils, and climate conditions characterizing farm environments a diverse species mix of mycorrhizae assures the best response. The endomycorrhizal inoculum used to form the mycorrhizal relationship can contain several selected mycorrhizal species. Glomus intraradices is one of the most studied and known to form the mycorrhizal association over a wide range of crop conditions. Glomus intraradices has been shown to be critical for nutrient and water uptake. Glomus mosseae and Glomus etunicatum produce a superior crop yield response by stimulating root development, protecting against drought, and increasing P uptake.

What types of mycorrhizal products are available? Mycorrhizal inoculum can be applied in a powder, granular or liquid form. Treating seed, either before or during sowing, produces excellent results. For example, one pound of the concentrated 4 species, mycorrhizal seed inoculant can treat enough seed to sow one acre(figure 6). Del Gates a farmer in North Dakota was able to increase flax yields from 22 to 28 bushels/acre. Ron Miller a wheat farmer in Nebraska increased his organic wheat yield from 12 to 17 bushels/acre using the same mycorrhizal seed inoculum. In Visalia, California, studies by United Agricultural Products documented a 20% increase in the yield of sorghum Sudan grass at 4 different seedings.

Conclusions

It is easy to forget about soil organisms. After all, most of the creatures living in the soil are out of sight. However, farmers clearly know the look and feel of productive soil that is the product of the living soil environment. Managing beneficial soil organisms can create and maintain healthy and profitable soil conditions. The “real dirt” on soil is this: it’s much more than minerals, air, water, and decaying organic matter. The soil has life and this life supports a productive farm. “Dirt is dead, but the soil is alive”.

The financial viability of the agricultural sector, as well as the health and social wellbeing of individuals, families and businesses in both rural and urban communities, are inexorably linked to the functioning of the land.

There is widespread agreement that the health of vegetation, soils and waterways in many parts of the Australian landscape have become seriously impaired, resulting in reduced resilience in the face of increasingly challenging climate variability.

Agriculture is the sector most strongly impacted by these changes. It is also the sector with the greatest potential for fundamental redesign. The Australian nation has the opportunity to be a world leader in the implementation of innovative technologies centred on adaptation to our variable climate.

In addition to enabling the farming community to more effectively deal with warmer, drier conditions, the restoration of landscape function will result in the active drawdown of excess CO2 from the atmosphere via stable biosequestration in soils.

Fundamental redesign of food, fuel and fertiliser production is vital to the survival and profitability of the Australian agricultural sector. We cannot afford to continue with business as usual.

While climate cannot be altered, the resilience of the agricultural sector can be markedly improved by changes to land management regimes. The most meaningful indicator for the health of the land, and the long-term wealth of a nation, is whether soil is being formed or lost. If soil is being lost, so too is the economic and ecological foundation on which production and conservation are based.

Completing the Carbon Cycle

Carbon is the basic building block for life. It is only a pollutant when in excess in the atmosphere or dissolved in water. Over millennia a highly effective carbon cycle has evolved to capture, store, transfer, release and recapture biochemical energy in the form of carbon compounds. The health of the soil – and therefore the vitality of plants, animals and people, depends of the effective functioning of this cycle.

 

All major greenhouse gases, including carbon dioxide, are cyclical. The issue is that too much CO2 is being emitted into the atmosphere and insufficient amounts are being sequestered. A ‘carbon pollution reduction’ agenda might therefore include:

(1) ‘completing the carbon cycle’ through active biosequestration of emitted CO2 into soils, the planet’s largest carbon sink, with a capacity five times greater than that of vegetation; and

(2) developing regional biofuel and biofertilizer capacity, reducing dependence on fossil fuels in the agricultural sector.

Emissions trading, while useful to focus public and corporate attention on the need to reduce carbon pollution, cannot of itself have significant impact on global concentrations of atmospheric CO2. It could however, be beneficial, if the funds raised were used to restore balance to the climate by supporting natural carbon, nitrogen and water cycles, via the restoration of perennial groundcover and soil microbial activity. Economic development is only sustainable if it strengthens, rather than depletes, natural resources.

Recent research has confirmed that the capacity of the ocean to act as a carbon sink has markedly declined, with the top 100 metres of water being close to CO2 saturation. This finding highlights the urgent need for ‘active drawdown’ of excess CO2 already in the atmosphere, as well as reducing further emissions.

The Soil Carbon Sink

Biosequestration in soil offers a practical and almost immediate solution to legacy load CO2.

Managing agricultural soils to enhance their capacity to sequester and store large volumes of atmospheric CO2 in the form of stable humus also has significant implications for soil structure, water-holding capacity and nutrient status. These factors strongly influence resilience, productivity and profitability onfarm, with flow-on benefits for local communities, landscape function, human health and regional and national economies.

Over 95% of terrestrial diversity is in the soil. In order for this life to flourish, the soil ecosystem requires fuel in the form of carbon (from green plants) and ‘habitat’ in the form of high root biomass. Further, the soil surface requires year-round protection from erosion and temperature extremes (both highs and lows).

Periodically bare soils generally contain only half the organic carbon of similar soils in the same region under perennial cover (for example, see table below). As a result they have poorer structure, lower soil water-holding capacity and reduced nutrient levels.

The data in the below table indicate that a change from annual groundcover (soil bare in summer) to perennial groundcover (healthy living soils all year round), has the potential to increase soil carbon levels by around 1% in low rainfall regions and up to 3% in higher rainfall regions.

An increase of 1% in the level of soil carbon in the 0-30cm soil profile equates to sequestration of 154 tons of CO2 per hectare (tCO2/ha) if an average bulk density of 1.4 g/cm3 is assumed, while an increase of 3% in the level of soil carbon equates to sequestration of 462 tCO2/ha.

When biologically friendly fertilisers and continuous sequestration (via perennial cover) are used in place of conventional fossil-fuel based fertilisers in traditional bare fallow systems, the carbon footprint is reversed (that is, more carbon is sequestered than emitted).

Irrespective of whether global temperatures increase, decrease or stay the same, the implementation of a national policy for soil carbon restoration utilising funds derived from the Federal Government’s Carbon Pollution Reduction Scheme would build ‘real’ wealth and ensure security of food and fresh water for the Australian nation.

Farming and Health

The best national health policy is good agricultural policy.

The key purpose of farming is — or should be — to produce nutritious food that benefits the health and well-being of the population. In reality, the farming sector sits at the centre of a complex, capital intensive supply chain focussed largely on production. Decisions are based on the cost of inputs and the anticipated value of outputs. Rarely is the nutritional value of the product considered. The health dimension has tended be viewed as a technical problem that can be fixed by an endless variety of pharmacological magic bullets — accompanied by seemingly limitless unpleasant side effects.

Low, normal and high ranges for average soil organic carbon levels (% by weight) in crop and pasture soils in
low rainfall (< 500mm) and high rainfall (> 500mm) regions, Victoria.

Interestingly, when people are asked which factors are of greatest importance to them personally, good health nearly always tops the list. Contrary to popular belief, good health is not determined by the quality of our medical system. Rather, it is closely linked to the nutrient content of food – which in turn is linked to the ecological health and organic carbon content of the soil in which food is grown.

Soil health and human health are more deeply connected than many people realise. Food is often viewed in terms of quantity available, hence ‘food scarcity’ is not seen as an issue in Australia. However, food produced from depleted soils does not contain the essential trace minerals required for the effective functioning of our immune systems.

The nutritional status of soils, plants, animals and people has fallen dramatically in the last 50 years, due to losses in soil carbon, the key driver for soil nutrient cycles. Soil carbon levels in turn are linked to the quality of groundcover.

Routine premature deaths by degenerative conditions such as cardiovascular disease and cancer have become prominent when they were once relatively uncommon. The cancer rate, for example, has increased from approximately 1 in 100, fifty years ago, to almost 1 in 2 today. The effectiveness of the human immune system has been severely compromised by increased exposure to more and more chemicals coupled with insufficient mineral density in food.

This situation can be dramatically improved by the integration of perennial groundcover and biology friendly fertilisers into agricultural production systems, reducing the need for chemical inputs and increasing the nutritive value of the food produced.

Livestock and Methane

Wetlands, rivers, oceans, lakes, plants, decaying vegetation (especially in moist environments such as rainforests) — and a wide variety of creatures great and small — including termites, camels, bison, bison, antelopes, reindeer, caribou and giraffes, have been producing methane for millions of years. A clear distinction needs to be made between natural methane from ruminants and man-made methane from industrial sources.

For example, a medium-sized whale produces methane emissions equivalent to 40 cows. There are international policies in place to protect whales and other methane producing wildlife, as well as protecting and enhancing methane-producing ecosystems such as wetlands and rainforests. The natural methane produced in the rumen of pasture fed livestock is not man-made — and is not increasing.

The largest single source of methane worldwide is wetlands (22%), followed by coal, oil and natural gas (19%), enteric fermentation (16%), rice cultivation (12%), with burning, landfill, sewage, manure, termites and release from the ocean making up the remaining 31%.

Global atmospheric levels of methane have remained relatively constant over the last ten years, despite increased ruminant numbers worldwide. This finding raises questions about the relative contribution of ruminant livestock to global methane levels and suggests that other sources and sinks may be playing a more significant role. Methane is broken down in the atmosphere within seven years by the free radical hydroxyl (OH), which is a naturally occurring process. This atmospheric cleanser has been shown to adjust itself up and down periodically and is believed to account for the stability in methane levels in the earth’s atmosphere over the last decade – that is, until a sudden increase in 2008.

A global study published in Geophysical Research Letters in October 2008 reported that the first increase in methane levels this century had been recorded in the last 12 months. This increase is thought to be due to rapidly accelerating methane hydrate emissions from the Arctic seabed. The findings from the Arctic research cast doubt on the value of attempting to suppress methane production from ruminants.

In Australia, ongoing dry conditions in many regions have resulted in falling stock numbers. Over the last two decades, livestock sources of methane have not increased in this country.

There is therefore no factual basis for selectively targeting ruminants for a ‘methane tax’ – or worse, interfering with this natural process. Why not a ‘carbon pollution tax’ on people, cats, dogs, horses, chickens, pigs — and marsupials — for all the CO2 collectively expired into the atmosphere? Or perhaps a ‘water vapour tax’ on all living creatures? Water vapour is the greenhouse gas that has increased to the greatest extent since the industrial revolution, accounting for 95% (by volume) of increased radiative forcing. Imposing penalties on people and animals for natural processes such as exhaling CO2 and water vapour makes as much sense as imposing a methane tax on livestock.

In appropriately managed rotationally grazed perennial grasslands and shrublands, green plants and the soil ecosystem ‘complete the carbon cycle’, ensuring more carbon is sequestered than emitted, easily compensating for the methane produced by livestock. It is interesting therefore, than none of the $26.8 million in Australian taxpayers money recently allocated to methane research included this aspect.

A complete life-cycle analysis would reveal that when the carbon footprint of fuel, fertiliser, herbicides and pesticides are factored in, plus erosion, water-quality decline and the carbon dioxide and nitrous oxide losses from soil, conventionally produced soybeans (or other sources of non-animal protein) would be less environmentally friendly than well-managed livestock grazing. Indeed, the fastest and most economical way to restore soils that have been degraded by annual cropping is through the use of rotationally grazed perennial pastures.

When the ecosystem services of clean air and clean water are taken into consideration, it becomes obvious that perennial groundcover provides benefits for all sectors of society, including urban dwellers. The sooner the completely illogical ‘eat vegan’ and ‘natural methane is a problem’ issues are resolved, the better. The evolution of the rumen as an efficient way of digesting plant material evolved around 90 million years ago. It seems extraordinarily inappropriate to interfere with this natural process.

Perennial groundcover, the biomass it produces and the livestock it feeds are all extremely beneficial (if not fundamental) to the planet, provided they are appropriately managed.

Mycorrhizal Fungi

Soil benefits in many ways from the presence of living plants year-round, due to reduced erosion, buffered temperatures, enhanced infiltration and markedly improved habitat for soil biota. Significantly, it is the photosynthetic capacity of living plants (rather than the amount of dead biomass added to soil) that is the main driver for soil carbon accumulation.

Mycorrhizal fungi differ quite significantly from decomposer type microbes in that they acquire their energy in a liquid form, as soluble carbon directly from actively growing plant roots. By this process they are actively drawing down atmospheric carbon and turning it into humus, often quite deep in the soil profile, where it is protected from oxidation.

Where mycorrhizae are functioning efficiently, 40-60% of the carbon fixed in green leaves can be channelled directly into soil as soluble carbon, where it is rapidly polymerised with minerals and nitrogen and converted to stable humic compounds in the soil food-web. The humates formed by soil biota are high molecular weight gel-like substances that hold between four and twenty times their own weight in water. Humic substances significantly improve soil structure, porosity, cation exchange capacity and plant growth.

Mycorrhizal fungi access and transport nutrients such as phosphorus, zinc and nitrogen in exchange for carbon from their living host. Plant growth is usually higher in the presence of mycorrhizal fungi than in their absence. In perennial grasslands, mycorrhizal fungi form extended networks that take several years to develop. They have mechanisms that enable them to survive while host plants are dormant but cannot survive if host plants are completely removed from the ecosystem.

Under appropriately managed perennial groundcover, soil water balance is improved by hydraulic lift and hydraulic redistribution in seasonally dry environments. These processes bring moisture to the rootzone that would not be available to an annual crop or pasture.

Broadacre cropping could benefit enormously from widely spaced rows or clumps of long-lived perennial grasses and fodder shrubs. As yet we do not know the required critical mass to restore soil ecosystem function, but it might only need to be 5-10% perennial cover. The benefit of permanent mycelial networks in terms of aggregate stability, porosity, improved soil water holding capacity, reduced erosivity and enhanced nutrient availability would be immense.

Where soil carbon is mycorrhizal in origin it is stable, which is vitally important in the current debate about soil carbon losses during droughts and fires. The stabilising humification process can also be enhanced via additions of certain humic materials (often included in biology-friendly fertilisers), which have a protective effect on soluble carbon exuded by plant roots.

Conclusion

The number of farmers in Australia has fallen 30 per cent in the last 20 years, with more than 10,000 farming families leaving the agricultural sector in the last five years alone. This decline is ongoing. There is also a reluctance on the part of young people to return to the land, indicative of the poor image and low incomeearning potential of current farming practices.

The longer we delay undertaking changes to land management, the more soil (and soil carbon and soil water) will be lost, exposing an increasingly fragile agricultural sector to escalating production risks, rising input costs and vulnerability to climatic extremes.

It’s time to move away from depletion-style, high emission, chemically based industrial agriculture and get serious about grass-roots biologically based alternatives.

The future of Australia depends on the future of our soil – and our willingness to look after it.

Answers to Global Warming in Our ‘Root Cellar’

From the food we eat to the air we breathe to the clothes we wear, humans depend on the thin covering of the earth’s surface we call soil. Arguably this thin and fragile layer of living topsoil is the Earth’s most critical natural resource. Soil is literally the “root cellar” for the planet, a storage area that feeds us and protects us in emergencies. It nurtures life in both forest and field and carves intricate paths that link the health of the land, sea, and atmosphere.

Lately, there has been tremendous attention given to carbon sequestration. Five to ten years ago, few had heard of or cared about the concept. Carbon sequestration has suddenly become a hot topic because the carbon in the air combines with oxygen to become carbon dioxide, a greenhouse gas that contributes to global warming.

Soils are key players in the process of storing (sequestering) and recycling carbon. According to Canada’s Department of Agriculture and the Environment, soils contain more than all the carbon in the atmosphere and three times more than is stored in all the Earth’s vegetation. Soil microbes break down decaying plant and animal matter in the process of creating fertile soils, and healthy soils containing billions of beneficial microorganisms and vigorous root systems have become an important carbon sink, binding up carbon that might otherwise enter the atmosphere.

The carbon absorbed from the atmosphere by plants and animals can take several paths before it re-enters the air as carbon dioxide. When a plant or animal dies, it is broken down by soil microorganisms. As the microorganisms consume the organic matter, they release some of the carbon into the atmosphere in the form of carbon dioxide. Some is destined for longer-term storage in roots and in the bodies of plant-eating or carnivorous animals. Animals then return more of the carbon to the atmosphere as CO2 through respiration, although some will be stored within their bodies until they die and decompose. Finally, like plants and animals decay, instead of escaping as carbon dioxide, a significant portion of their carbon becomes part of the organic component in soils through the activities of essential soil organisms. These beneficial microorganisms work to produce a substance known as humus, a stable, rich component of soil that is the color of dark chocolate and loaded with carbon.

HISTORY LESSON

When frequent tillage is introduced, long chains of carbon that are the essence of humus are converted into carbon dioxide, which releases into the atmosphere. Soil depleted of the humic fraction is more prone to erosion, loss of microbial diversity, and a breakdown of the structure and can support fewer animals and plants. “Organic matter is the elixir of microbial life in the soil,” explains Dr. Dave Perry, professor, and ecologist at Oregon State University. “It holds water, preventing drought and floods, it supports the living soil organisms that hold the key to sustain plant growth, and it is a reservoir of carbon that plays a key role in global climate change.”

Soils can contain a wide range of organic matter. Most topsoils range from 1 to 20 percent organic matter. The best agricultural lands have loamy topsoil in which there is a high concentration of organic matter. Some of the richest in the world were found in the Great Plains of the central United States, where perennial grasses, their roots systems, and associated soil organisms over thousands of years built up deep layers of carbon-laden topsoil. They form continuously, but very slowly. Only about one inch of soil is formed every 500 to 1,000 years, so the loss of good topsoil is a serious issue that has led to the rise and fall of civilizations.

The great early civilizations of Mesopotamia, for example, arose because of the richness of their soils and collapsed because of declines in soil quality. Poor land management and excessive irrigation caused soils to become increasingly degraded and unable to support the Fertile Crescent civilizations. Ancient Greece suffered a similar fate. The philosopher Plato, writing around 360 B.C., attributed the demise of Greek dominance to soil degradation: “In earlier days Attica yielded far more abundant produce. In a comparison of what then was, there are remaining only the bones of the wasted body; all the richer and softer parts of the soil having fallen away, and the mere skeleton of the land being left.” What Plato likely did not recognize is how much carbon had washed away from these Greek soils.

In the New World, similar processes were unfolding. Harvard Professor Sylvanus Morley concluded back in the 1930s that the great Mayan Civilization of Mesoamerica collapsed because they overshot the carrying capacity of the land. Deforestation and erosion exhausted their resource base. Mayans died of starvation and thirst in mass, and others fled once-great cities, leaving them as silent warnings for generations to come.

UCLA professor Jared Diamond, author of the books Guns, Germs and Steel and Collapse, argues that most inhabitants of Easter Island in the Pacific died because of deforestation, erosion and soil depletion. In Iceland, farming and human activities caused about 50 percent of the soil to end up in the sea, explains Diamond, concluding, “Icelandic society
survived only through a drastically lower standard of living.” Not surprisingly, the the practice of destroying soils by torching watersheds or salting farms and fields has been employed by armies in warfare from the time of Alexander the Great to Napoleon.

Today, we are facing many of the same issues: removal of native vegetation, over-harvest, dwindling supplies of freshwater, overworked soils, and sprawling population growth. Our poor management of the land has resulted in serious warning signs. Widespread agricultural pollution of lands and seas accelerated topsoil loss, damage to fish and aquatic life, pesticide buildup in our bodies, and rapidly declining nutritional value of food have become environmental problems of immense importance that are directly related to soil. Now is the time to bring attention to the critical role our management of soil plays in another environmental issue of great significance: global climate change.

FIRST LESSON

How do we stop the degradation of our soils? The answers can be found in nature below the soil surface in our “root cellar.” A favorite habitat of microbes is near and in the roots of plants. Although many of them live throughout the soil, up to 100 times more live close to the roots of plants.

This area near the roots is called the rhizosphere, the thin layer of soil surrounding the roots. Some microbes have such a close relationship with plants that they actually live inside the plant, such as beneficial mycorrhizal fungi. Their threads penetrate into the root and secure sugars provided by the plant to fuel their growth. In exchange, these same filaments radiate out from the root into the surrounding soil where they capture nutrients and water and transport these materials back to the plant. It is estimated that mycorrhizal fungal filaments explore hundreds to thousands of times more soil volume than roots alone.

Endo mycorrhizae, also known as arbuscular mycorrhizae, are the symbiotic association of fungus and roots that occur on more plant species than all other types of mycorrhizae combined. They have been observed in the roots of more than 1,000 genera of plants representing some 200 families. It has been estimated that more than 85 to 90 percent of the estimated 400,000 species of vascular plants in the world form arbuscular mycorrhizae. These include most grains, vegetables, fruit and nut trees, vines, and turf grasses.

Benefits of mycorrhizae include:

• Improved nutrient and water uptake;

• Improved root growth;

• Improved plant growth and yield;

• Reduced transplant shock;

• Reduced drought stress.

Some modern agricultural practices reduce the biological activity in the soil.

Certain pesticides, chemical fertilizers, intensive cultivation, compaction, organic matter loss, and erosion adversely affect beneficial mycorrhizal fungi. An extensive body of laboratory testing indicates that the majority of intensively managed agricultural lands lack adequate populations of mycorrhizal fungi. Farming widespread areas affects the plant/mycorrhizal relationship in two fundamental ways. First, it isolates the plant from beneficial mycorrhizal fungi available in natural settings. Second, it increases a healthy crop’s need for water, nutrients, and soil structure.

Once lost from a farm, endomycorrhizal populations are slow to recolonize unless there is close access to natural areas that can act as a source of mycorrhizal spores. Endomycorrhizal fungi do not disperse their spores in the wind but must grow from root to root or be dispersed by animals, so close proximity to healthy and undisturbed natural sites may be necessary. Normally though, farmers seldom have the opportunity to grow their crops immediately adjacent to undisturbed natural ecosystems.

Inoculating farmland soils with mycorrhizal fungi before, during, or following planting can improve crop establishment, growth, yield, and carbon sequestration. Mycorrhizal inoculants are available in liquid, powder, and granular forms and can be sprinkled onto roots during transplanting, banded beneath seed, used as a seed coating, or watered in via existing irrigation systems. The goal is to create physical contact between the mycorrhizal inoculant and the crop roots, and the type of application depends upon the farmer’s equipment and needs. Inoculants that are concentrated and contain several species of mycorrhizal fungi produce the best results. The cost of inoculation generally ranges from $17 to $37 per acre.

CARBON-RICH SUPERGLUE

Mycorrhizae also perform another service for the ecosystem that has only recently come to light. The USDA published a report by Don Comis on work by Sara F. Wright and Kristine A. Nichols that suggests a substance called glomalin, discovered by Wright in 1996, does indeed “glom” onto a large amount of carbon. The glomalin molecule is made up of 30-40 percent carbon and represents up to 30 percent of the carbon in the soil. It is a natural superglue that binds organic matter to mineral particles in the soil. It also forms soil clumps — aggregates — that improve soil structure and keep other soil carbon from escaping. It is in fact glomalin that gives soil its tilth — a subtle texture that enables experienced farmers to identify great soil by feeling for the smooth granules as they flow through their fingers. Glomalin is relatively stable in soils, lasting anywhere from seven to 42 years.

Endo mycorrhizae form with nearly all the important agricultural plants (with the exception of the brassicas). Glomalin (produced by the endomycorrhizal fungal group Glomus, hence the name) is produced by endomycorrhizal fungi established on a plant’s roots. The fungi produce glomalin from carbon they trade for other nutrients and water, apparently to seal themselves and gain enough rigidity to carry materials across the air spaces between soil particles. Sara F. Wright’s discovery of glomalin is causing a complete reexamination of soil organic matter. It is increasingly being included in studies of carbon storage and soil quality.

CO2 & GLOMALIN

In an earlier study, Wright and scientists from the University of California at Riverside and Stanford University showed that higher CO2 levels in the atmosphere stimulate the fungi to produce more glomalin. A three-year study was done on semiarid shrubland, and a six-year study was conducted on grasslands in San Diego County, California, using outdoor chambers with controlled CO2 levels. When atmospheric CO2 reached 670 parts per million — the level predicted for the middle to late 21st century — mycorrhizal fungal filaments (hyphae) grew three times as long and produced five times as much glomalin as fungi on plants growing with today’s ambient level of 370 ppm.

Longer hyphae help plants reach more water and nutrients, which could help plants face drought in a warmer climate. The increase in glomalin production helps soil build defenses against degradation and erosion and boosts its productivity. Wright says all these benefits can also come from good tillage and soil management techniques rather than higher atmospheric CO2. “You can still raise glomalin levels, improve soil structure, and increase carbon storage,” she notes.

Forests, croplands, and grasslands around the world are potentially valuable for offsetting carbon dioxide emissions from industry and vehicles. In fact, some private markets have already started offering carbon credits for sale by owners of such land. The industry could buy the credits as offsets for their emissions. The expectation is that these credits would be traded just as pollution credits are currently traded worldwide. Although such plans risk abuse by industrial polluters and are thus controversial, the importance of our crops, forests, and grasslands in offsetting the environmental damage caused by human technology is unquestionable.

SECOND LESSON

Today most human food comes from legumes, oilseed crops, and cereal grains. It is estimated that 80 percent of agricultural land is occupied by these crops. These human staples are relatively high in protein and calories and easy to store and transport, thus making them attractive to both consumers and producers. However, these annual crops must be grown from seed every year, generally using fossil-fuel intensive cultivation and fertilization methods. To maintain annual yields, farmers are faced with growing input costs for seed, fuel, fertilizer, pesticides, and herbicides. All these practices, including tillage, consume or release large amounts of carbon dioxide into the atmosphere. In addition, erosion and runoff from these intensively cultivated lands can pollute freshwater supplies and degrade the soil.

Data from the Rodale Institute’s long-running comparison of organic and conventional cropping systems confirms that organic methods are far more effective at removing carbon dioxide from the atmosphere and fixing it as beneficial organic matter in the soil. Data from 23 years of continuous research inside-by-side fields is conclusive: the organic system has shown an increase in soil carbon of 15-28 percent, compared to no increase in the non-organic system. Dr. David Douds of the Agricultural Research Service suggests that healthy mycorrhizal fungi populations in organic systems are key to the increase in soil carbon. In addition, a recent study of energy inputs conducted by Dr. David Pimentel of Cornell University found that organic farming systems use just 63 percent of the energy required by conventional farming systems, largely because of the massive amounts of energy required to synthesize nitrogen fertilizer. This is big news. Organic farming with help from mycorrhizal fungi can take massive amounts of carbon dioxide out of the air. If all 160 million acres of corn and soybeans in the United States were converted to organic production, the reduction in atmospheric CO2 could translate to:

• 57.7 million cars off the road (20 percent of the cars in the United States!);

• 773 billion car miles not driven.

Let’s look at nature’s “root cellar” as an example of how the system works — for example, a native tall-grass prairie in the Midwest. These prairie systems were productive year after year and needed no fertilizers, pesticides, or herbicides. Pests and diseases were almost nonexistent. Over time prairie soils built and maintained deep and carbon-rich productive topsoil. It is a soil legacy that helped make America prosperous. Compared to perennial grasses, annual crops such as wheat, corn, sunflowers, and sorghum have relatively shallow root systems. The vast majority of annual roots are confined to the top foot of soil. These root systems die after harvest, leaving non-vegetated soil exposed to erosion of precious topsoil. Perennial root systems, on the other hand, commonly exceed 6 feet in depth and maintain this living tissue year-round. This allows perennial grasses to be resilient in the face of extremes of environment and to sprout into action when warm temperatures, water, and nutrients become available. Deep perennial grassroots systems and associated mycorrhizal fungi reduce fertilizer losses, conserve water, and boost the soil’s storage of carbon. Roots and mycorrhizal fungi pump carbon-rich plant sugars such as glomalin into the soil, feeding beneficial soil organism that conserves and access soil nutrients.

Perennial roots themselves become a root cellar of stored carbon. Deep root systems capture and utilize more rainwater than shallow root systems, thus reducing off-site movement of water and nutrients. In addition, perennial grasses do not have to be planted every year, thus reducing the consumption of fuel by farm machinery. Perennial root systems and associated mycorrhizal fungi tie up soil resources, discouraging invasions of weeds. Pesticide, herbicide, and fertilizer use are greatly diminished, which again lowers the number of fossil fuels needed on the farm. Greater root depths, longer growing seasons for roots, and mycorrhizal fungi let perennials sequester carbon at a rate 50 percent higher than an annually cropped field.

For all of these reasons, plant breeders both in the United States and internationally have initiated breeding programs to develop wheat, sunflower, sorghum, and intermediate wheatgrass as perennial grain crops. While still in the early stages, plant geneticists such as Wes Jackson in Kansas are making progress. The Land Institute, a nonprofit founded by Jackson, has discovered that of the 13 most widely grown grain and oilseed crops, 10 are capable of hybridization with perennial relatives. The widespread production of high-yield perennial grain crops, if successful, could have a major positive impact on both the environment and the sequestration of carbon in the root cellar.

CONCLUSIONS

Hidden underground in our planet’s root cellar, nature has given us a template to help us resolve a variety of serious environmental issues, including global warming. Often overlooked and underappreciated, the living soil holds the key to the future. Vigorous long-lasting root systems and associated tiny fungal threads can accumulate and store vast amounts of carbon. Are we destined to relive the mistakes of previous civilizations or are we wise enough to learn from natural systems? It’s time to examine our root cellar for solutions.