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Farmers have a golden solution to global warming largely missed by climate change pundits, right beneath their feet. The innovative Australian Soil Carbon Accreditation Scheme is showing how incentive payments can be received by landholders for measurable increases in soil carbon that soaks up CO2 from the atmosphere. Financial incentives could help fund soil restoration efforts, which in turn bring the bonus of greater productivity, drought resilience and even rain. The action is deep underground.


By increasing soil carbon through biologically based techniques, Australian farmers can benefit the environment and their budgets.

Australian soil scientist Dr Christine Jones is frustrated that the world hasn’t fully cottoned on to the important role of healthy crop roots and soils to draw down massive amounts of carbon, buffer drought and re-supply essential nutrients which have been drained from our landscape and farm produce by traditional agricultural practices.

Her 10-year crusade to raise the profile of soil carbon processes and what she calls the microbial ‘carbon highway’ led to the foundation of the organization Amazing Carbon and then to the development and leadership of the Australian Soil Carbon Accreditation Scheme (ASCAS).

ASCAS is a vehicle to demonstrate through farm trials that with biologically based protocols involving perennial (long-lived) deep-rooted pastures and annual crops, measured increases in vital soil carbon can be achieved quickly and rewarded with incentive payments for the CO 2 sequestered. The scheme is the first of its kind in the Southern Hemisphere, making Australia an early leader in the recognition of soils as a verifiable carbon sink.

The ASCAS project is also collecting much-needed hard data on soil carbon accumulation rates across various properties and soil types in the Northern Agricultural Region (NAR) of Western Australia and central Queensland, two of the areas hardest hit by climate change.

After the oceans, the soil is the earth’s largest carbon sink – but plants are the facilitators. Through photosynthesis plants convert CO 2 to sugars to power growth, releasing oxygen into the atmosphere. The activities of symbiotic bacteria and fungi, associated with roots and fed by the sugars, enable the exuded carbon to be combined with soil minerals and made into stable humus1 which locks the carbon away.

The fundamental processes which produce humified soil carbon are part of the microbial bridge – the focus of Dr Jones’ interest – and the key to the formation and maintenance of healthy topsoils with high moisture-holding capacity, which largely determines plant and crop productivity.

‘This can’t happen where farm chemicals kill the essential soil microbes,’ says Dr. Jones. ‘When chemical use is added to intensive cultivation, which exposes and oxidizes the humus already in the soil, it is easy to see why soil has become a huge net source rather than a net “sink” for atmospheric CO2 under current farming practices.’

Alongside this, the removal of groundcover interrupts the important water and climate cycles facilitated by plants. Photosynthesis is a cooling process. Lack of green cover on the land greatly increases heat absorption, causing a dramatic increase in evaporation. Water vapor is a greenhouse gas of greater significance for global warming than CO 2. Lower rainfall can also result from groundcover loss.

Under conventional cropping practices, soil carbon in Australia has declined to one-half to one-third of original levels. CSIRO research has found that the rate of carbon sequestration resulting from good continuous pastures is enough to maintain or increase soil carbon levels, but all other crops/pasture rotations cause a decline of surface soil carbon.

1. A duster applies fungicide to a crop in Virginia in South Australia. While they convey short-term benefits, the application of chemicals to farm soils harms their function and fertility over the long term, causing the release of carbon.2.Carbon-poor farmland after rain (right), showing waterlogging due to poor structure. The denser groundcover of the adjacent stock route (left) results in higher soil carbon, better structure, and improved water-holding capacity.

Dr. Jones claims that conventional approaches to modeling soil carbon, while useful for describing soil carbon loss, are inadequate for determining soil carbon gain. Soil carbon models such as Roth C do not take into account the humification of root exudates or contributions from mycorrhizal fungi. ‘Sequestration rates under regenerative agricultural regimes may be quite a bit higher than estimated by current models,’ she says.

The scheme is the first of its kind in the Southern Hemisphere, making Australia an early leader in the recognition of soils as a verifiable carbon sink.

A cow browses one of many rows of tagasaste planted on Bob Wilson’s property at Lancelin, WA.

Tim Wiley, Development Officer with Western Australia’s Department of Agriculture and Food, was quick to realize the great potential of soil carbon increases with perennials. Wiley has been supporting the ASCAS trials in the NAR of WA. ‘The trend is clear – perennial pastures sequester 5 to 10 tonnes of CO 2 per hectare annually.’ He says with changes to farming practice, landholders in the northern agricultural areas of WA could sequester these amounts of CO 2 over two million hectares of poor sandy soil.

‘If all WA’s agricultural soils were sequestering carbon, we would soak up WA’s current emissions. This would have the potential to significantly decrease Australia’s net emissions and meet our Kyoto obligations.’

Add in the rest of Australia’s agricultural land area – and the world’s – and the impact on global CO2 levels is evident. Wiley pointed to current cost and data limitations to quantitative measurements of soil carbon. ‘We don’t know enough about carbon under different farming systems,’ he said. ‘We have data from farmer sampling before and after perennials were planted and over-the-fence comparisons, but it is not rigorous enough.

‘To trade carbon we need a working model such as Roth C for estimating changes in carbon. The model results would be verified by occasional soil sampling of farmers’ paddocks. Roth C needs to be validated with data from long-term trials in the regions that accurately measure carbon.’ That’s where the ASCAS trials are filling in the picture.

Up at Lancelin, about 140 km north of Perth, things have been tough during the last 10 years of below-average rainfall. But cattle farmer Bob Wilson hasn’t been too fazed; since changing his farming system over the past 20 years from traditional annual pastures to the fast-growing fodder shrub, tagasaste, and subtropical perennial (permanent) grasses, his farm has ridden out the dry far better than most, producing good returns.

As a member of the Evergreen Farming Group, he hasn’t been surprised by the exciting results of the ASCAS trials. His band of farmers advocates growing hardier perennial plants which improve the soil and help stave off salinity. Two decades ago the view to the future of farming opened up for Wilson and his colleagues, and it looked much greener.

Unlike some of the other farmers involved in the ASCAS trials, Wilson has been growing perennials for some time. Using the scheme’s protocols he has been able to measure soil carbon on his land and quantify to some extent how it can improve yields, increase water and nutrient retention for greater farm vigour, and now, potentially bring useful credit income for sequestering carbon dioxide.

He now has half his 2000 ha under tagasaste in wide rows with annual pastures in between. ‘I changed my farming system because of concern for the environment, wind erosion, and our need for an extended grazing season. We have doubled our carrying capacity.’

But he points out that while subtropical perennials provide an extended period of green feed, they grow slowly during winter and are susceptible to frosts. ‘We need annuals as well for winter feed. A mixture of pasture types is best, on a case by case basis,’ he says. When Tim Wiley dug soil pits in Bob Wilson’s paddocks, he found perennial grass roots at the bottom of a 2.5 m deep pit and tagasaste roots at the bottom of a 3 m pit. He calculated from the soil test and other results that the perennial grasses and tagasaste were sequestering 7 t/ha of CO2 per year more than traditional annual

Department of Primary Industries and Fisheries Extension Agronomist Stuart Buck and Principal Technical Officer Maurie Conway drill sample soil cores as part of ASCAS trials northeast of Clermont in central Queensland. Testing is repeated in the same place each year to determine annual changes in soil carbon content. The soil under this crop contained over 3% carbon at the surface and 4% total carbon at 110 cm.

The group of 12 farmers involved in ASCAS ‘benchmarking’ in the Northern Agricultural Region of WA over the last year will later in 2008 be completing calculations to see how much carbon has been sequestered under their perennial pastures. Baseline soil carbon levels in five increments in the 110 cm soil profile were determined during August 2007 within Defined Sequestration Areas on their properties.

Results from the first 12 months of field trials in Queensland will also be known later this year. Dr. Jones says the initial findings have been exciting. ‘One of the broadacre cropping properties north-east of Clermont in Queensland that is participating in the ASCAS project has more than three times the amount of carbon in the farmed soil than there is under the surrounding native vegetation (149 tonnes of carbon/ha under native vegetation versus 516 tonnes of carbon/ha under the crop). As a result, the soil is far more productive. The wheat crop yielded 4 tonnes per hectare of grain with 13.5 percent protein this year – well above the district average.

‘This demonstrates that with the right kind of farming (in this case zero till with microbial stimulants in place of harsh fertilizers) we can dramatically improve soil health. I’m not saying we should replace native vegetation with farmed land – far from it. What I am saying is there is still hope for much of the land that we have inadvertently almost totally destroyed,’ she observes.

1. Carbon-rich topsoil from beneath perennial grass (left hand) compared to adjacent carbon-poor soil (right hand). By holding more air, sustaining moisture, and having higher bioavailabilities of soil nutrients, carbon-rich soils benefit plants and soil biota.2.Plant roots provide habitat for soil biota and exude carbon, both of which are important for humification and soil-carbon stabilization. Continuous grazing stunts grass root systems (left), which are more robust under rest-rotation grazing (right).

Under the Australian Soil Carbon Accreditation Scheme, participating farmers will receive Soil Carbon Incentive Payments (SCIPS) calculated at one-hundredth the 100-year rate ($25 per tonne CO 2 sequestered).

The incentive payments made to farmers are a private donation from Rhonda Willson, Executive Chairman, John While Springs (S) Pte Ltd and Director, Gilgai Australia.

Receipt of Soil Carbon Incentive Payments will be 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.

Agricultural soils have short-, medium, and long-term potential to mitigate climate change by sequestering atmospheric carbon as beneficial humified organic matter. Results from overseas studies indicate that the carbon sequestration potential of appropriately managed farmlands can be higher than that of tropical forests. In countries such as Brazil, Colombia, Costa Rica, Mexico, and Cuba, the science of soil carbon is the subject of active research and development.

Dr. Jones says the rationale for the ASCAS trials was to demonstrate that significant quantities of soil carbon could be sequestered on Australia’s commercial properties, even under difficult environmental conditions, provided appropriate land management technologies were employed.

Dr. Christine Jones is advocating more focus on the role of soil carbon mechanisms in restoring landscapes and sequestering atmospheric carbon.

Apart from needing to be rapid, stable, and applicable to large areas, soil carbon sequestration as an effective climate mitigating tool must involve low-cost, easily implemented, innovative land management techniques that differ substantially from ‘business as usual. There also needs to be effective monitoring, evaluation, and verification, particularly when measures of carbon sequestered might be linked to a financial mechanism.

At present, an emissions trading scheme does not operate in Australia, although a national scheme is planned in line with the government’s recent ratification of the Kyoto accord. Rio Tinto Coal Australia is currently one of the organizations funding research into soil carbon and its potential for a future carbon trading scheme under ASCAS.

Recent good news is that Australian agricultural products company Incitec Pivot Ltd has also come on board as a supporter of the Queensland field trials. Of the estimated 3060 gigatonnes of carbon in the terrestrial biosphere, 82 percent is in soils.2 That’s over four times the amount of carbon stored in the world’s vegetation. Dr. Jones asks, ‘If only 18 percent is stored in vegetation, why all the emphasis on biomass, rather than soil, as a carbon sink?

‘The answer is that people – including most of our top scientists – simply don’t understand soil carbon sequestration or the role of the microbial bridge and have therefore overlooked it.

‘ASCAS was established so that farmers could receive incentive payments for increases in their soil carbon. We’re demonstrating the incredible rates at which carbon can be put into soil by roots in biologically based sustainable cropping and grazing systems,’ she says.

‘Effective soil carbon management is a key factor for productive farms, revitalized catchments, and a greener planet.

‘Incentive payments for regenerative land management would help to “cash flow” the multiple natural resource management and environmental benefits that accompany increased levels of carbon in soils.’

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Building soil carbon with Yearlong Green Farming

The capacity for appropriately managed soils to sequester atmospheric carbon is enormous. The world’s soils hold around three times as much carbon as the atmosphere and over four times as much carbon as the vegetation. Soil represents the largest carbon sink over which we have control.

When atmospheric carbon is sequestered in topsoil as organic carbon, it brings with it a wealth of environmental, productivity and quality of life benefits. An understanding of the ‘carbon cycle’ and the role of carbon in soils, is essential to our understanding of life on earth.

Building soil carbon requires green plants and soil microbes. ‘There are 4 steps to ‘turning air into soil’

i) Photosynthesis

ii) Resynthesis

iii) Exudation

iv) Humification

Photosynthesis is a two-step endothermic reaction (ie a cooling process) which takes place in the chloroplasts of green leaves. Incoming light energy (sunlight) is captured and stored as biochemical energy in the form of a simple sugar – glucose (C6H12O6), using carbon dioxide (CO2) from the air and water (H2O) from the soil. Oxygen is released to the atmosphere.

Photosynthesis requires 15 MJ of sunlight energy for every kilogram of glucose produced. If the same 15 MJ of incoming light energy makes contact with a bare surface, such as bare ground, it is reflected, absorbed or radiated – as heat, usually accompanied by moisture. The respective area of the earth’s surface covered by either actively growing crops and pastures, or bare ground, has a significant effect on global climate.

Resynthesis: Through a myriad of chemical reactions, the glucose formed during photosynthesis is resynthesised to a wide variety of carbon compounds, including carbohydrates, proteins, organic acids, waxes and oils. Carbon atoms can link together to form long chains, branched chains and rings, to which other elements, such as hydrogen and oxygen, can join.

The energy captured during photosynthesis and stored in carbon compounds serves as ‘fuel’ for life on earth. Carbohydrates such as cellulose provide energy for grazing animals, the starch in grains provides energy for livestock and people. The carbon stored in previous eras as ‘fossil fuels’ (hydrocarbons) such as coal, oil and gas provides energy for vehicles, machinery and industry.



Figure 1. Root volume, rhizosphere surface area, exudation of carbon, microbial activity, humification, and soil building are highly correlated with the perenniality and vigour of groundcover plants.

Exudation: Around 30-40% of the carbon fixed by grass plants during photosynthesis is exuded into the soil to form a microbial bridge (to feed the microbes that enhance the availability of essential plant nutrients). In this way, actively growing crops and pastures provide ‘fuel’ for the soil engine.

Carbon compounds are essential to the creation of topsoil from the structureless, lifeless mineral soil produced by the weathering of rocks.

Organic carbon additions are governed by the volume of plant roots per unit of soil and their rate of growth. The more active green leaves there are, the more roots there are, the more carbon is added. It’s as simple as that (Figure 1). The breakdown of fibrous roots pruned into the soil through rest-rotation grazing is also an important source of carbon in soils.

Humification: Adding organic carbon to soil is one thing, keeping it there is another. Organic carbon moves between various ‘pools’ in the soil, some of which are short-lived while others may persist for thousands of years. Carbon additions need to be combined with land management practices that foster the conversion of relatively transient forms of organic carbon to more stable complexes within the soil.

In the humification process, soil microbes resynthesize and polymerize labile carbon (exuded from plant roots) into high molecular weight stable humic substances. Humus, a gel-like substance that forms an integral component of the soil matrix, is the best known of the stable organic fractions.

Humification cannot proceed unless there is a continuous supply of ‘fuel’ for soil microbes. If humification does not occur, the carbon exuded from plant roots (or added to soil as plant residues or manure) simply oxidizes and recycles back to the atmosphere as carbon dioxide.

Humic substances have significance beyond the relatively long-term sequestration of atmospheric carbon. They are extremely important in pH buffering, inactivation of pesticides and other pollutants, improved plant nutrition, and increased soil-water-holding capacity. By chelating salts, humic substances can also effectively ameliorate the symptoms of dryland salinity. Increasing the rate of humification has highly significant effects on the health and productivity of agricultural land.

Importance of soil fungi

Most perennial grasses are excellent hosts for mycorrhizal fungi, with up to 100 meters of microscopic fungi forming per gram of soil under healthy grassland. Glomalin is a glycoprotein (contains both protein and carbohydrate) produced by arbuscular mycorrhizal fungi living on plant roots. Glomalin can persist for several decades and may account for one-third of the stable organic carbon stored in agricultural soils.

Mycorrhizal fungi and glomalin production are inhibited by bare soil, intensive tillage, the application of phosphorus fertilizer, and the presence of plants from the Brassica family such as canola, which do not form mycorrhizal associations.

Maintaining soil structure

‘Aggregation’ is part of the humification and soil carbon building process and is essential for maintaining soil structure. Glues and gums from fungal hyphae in the rhizosphere enable the formation of peds or lumps (which can be seen with the naked eye, often attached to plant roots). The presence of these aggregates creates macropores (spaces between the aggregates) which markedly improve the infiltration of water. After rain less water sits on the soil surface and waterlogging is reduced. As structure continues to improve, smaller and smaller aggregates are formed, along with soil mesopores and micropores, dramatically improving soil function, aeration, levels of biological activity, and resilience.

Soil structure is not permanent. Aggregates made from microbial substances are continually breaking down and rebuilding. An ongoing supply of energy in the form of carbon from actively growing plant roots will maintain soil structure. If soils are left without green groundcover for long periods they can become compacted, blow or wash away.

Under conventional cropping or set-stocked annual pastures, the stimulatory exudates produced by short-lived species are negated by bare earth at other times of the year. The result is a decline in levels of soil carbon, soil structure, and soil function. Soil building requires green plants and soil cover for as much of the year as possible. In seasonal rainfall environments, a mix of perennial groundcover species enables response to rain at any time. In grazing enterprises, rest-rotation grazing is absolutely essential. For broadacre cropping, the presence of out-of-season groundcover ensures stability, long-term productivity, and soil building rather than soil destruction.

Any farming practice that improves soil structure is building soil carbon. Water, energy, life, nutrients, and profit will increase on-farm as soil organic carbon levels rise. The alternative is the evaporation of water, energy, life, nutrients, and profit if carbon is mismanaged and goes into the air.

Yearlong Green Farming (YGF) is any practice of turning bare soil into soil covered with green plants. YGF increases the quality, quantity, and perenniality of green groundcover in broadacre cropping, horticultural, forestry and grazing enterprises.

Many benefits of Pasture Cropping, for example, can be attributed to having perennial grasses and cereals together side by side in space and time. Ongoing carbon additions from the perennial grass component evolve into highly stable forms of soil carbon while the short-term, high sugar forms of carbon exuded by the cereal crop roots stimulate microbial activity.

As a bonus, regenerative farming practices such as Pasture Cropping result in the production of food much higher in vitamin and mineral content and lower in herbicide and pesticide residues than conventionally produced foods.

Rewarding farmers for Yearlong Green Farming practices that build new topsoil and raise levels of organic carbon would have a significant impact on the vitality and productivity of Australia’s rural industries. YGF would also reduce evaporation and heat radiation from bare soil surfaces, reduce the incidence of dryland salinity and counteract soil acidity.

Under regenerative regimes, soil carbon and soil life are restored, conferring multiple ecological and production benefits in terms of nutrient cycling, soil water storage, soil structural integrity, and disease suppression. Benefits extend well beyond the paddock gate. Improved soil and water quality are the ‘key’ to catchment health, while YGF represents the most potent mechanism available for mitigating climate change.

It’s about turning carbon loss into carbon gain.

Getting started in lifeless, compacted soils where the soil engine has shut down is the hard part. The longer we delay, the more difficult it will be to re-sequester soil carbon and re-balance the greenhouse equation.

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Mycorrhizal Fungi Nitrogen Transfer Discovery

Another source of nitrogen uptake unique to mycorrhizal symbiosis has recently been discovered – it involves the direct transfer of nitrogen-laden amino acids from the fungus into the cereal plant roots. 1. Amino acids inside mycorrhizal hyphae 2. Amino acids have entered the root from mycorrhizal hyphae

Let’s begin with a topic that interests all farmers and one to which nearly all the other benefits of mycorrhizae are inherently linked: improving crop yields. Typically, mycorrhizae’s single most prominent contribution to a crop plant is improved access to and uptake of phosphorus (P).

All farmers are intensely familiar with the importance of this elemental nutrient to essential plant functions, which include energy transfer, photosynthesis, the transformation of carbohydrates, systemic nutrient mobilization, and genetic transfers. Given that often one of the most noticeable evidence of P deficiency in a crop is reduced yield (or in forage and pasture reduced quantity), it is no wonder that P is such a critical (and expensive) component in crop fertilizers.

Much of the naturally-occurring P in soils is found bound tightly with elements such as iron or aluminum in the form of recalcitrant compounds. Similarly, P inputs derived from fertilizers often react with ambient soil cations to form insoluble salts. In natural ecosystems, plant communities rely on mycorrhizal fungi to access these forms of phosphorus.

Mycorrhizal hyphae produce enzymes, including phosphatase to convert phosphorus into soluble, plant-usable forms. This same process can be valuable in agriculture, maximizing the availability of natural soil P as well as dramatically enhancing the efficient uptake of P derived from fertilizers. With greater P uptake, costs go down and yields frequently increase as well.

The availability of nitrogen can also be a factor in limiting crop productivity for reasons opposite to those limiting P. Available nitrogen in the forms of nitrates (N03), nitrites (N02), and ammonium (NH4) are very soluble and can flow past the root zone before roots can absorb it. This means they are often lost to run-off or groundwater or trapped in subsoil beyond the access of roots.

The profoundly dense network of tiny hyphae filaments in a mycorrhizal system typically extends 45 to 60 centimeters beyond the roots themselves, increasing the absorptive surface area of colonized roots hundreds to thousands of times. A teaspoon of mycorrhizal soil can easily contain several kilometers of hyphae, all of which are highly absorptive of soluble nitrogen ions, ensuring optimum uptake and the associated nitrogen-related cropping benefits.

Another source of nitrogen uptake unique to mycorrhizal symbiosis has recently been discovered by scientists at the University of California, Irvine, US. The researchers set out to explore how nutrients, including nitrogen, are mobilized through the environment. Using cutting-edge technology, nanometre-sized bits of a semiconducting material called quantum dots were attached to organic compounds such as nitrogen-laden amino acids.

Nutrient transfer discovery

When energised by an ultraviolet laser, the tiny dots emitted light, becoming detectable by special cameras positioned in the root zone of plants. In this manner, the scientists could track nutrients as they were absorbed into the microscopic mycorrhizal hyphae and follow their subsequent movement into the tissue of the host plant.

For more than 100 years conventional scientific wisdom held that root absorption of nitrogen was restricted to inorganic forms of nitrogen such as N03, N02, and NH4. But to their surprise, the scientists saw the illuminated dots attached to amino acids enter the mycorrhizal hyphae and observed them as entire molecules moved into the root cell vacuoles and then continued systemically to the chloroplasts (in which nitrogen is used for photosynthesis).


In non-mycorrhizal rhizospheres, amino acids, which are the primary components of proteins, must undergo extensive and time-consuming decomposition processes by bacteria and other soil organisms before nitrogen is released in inorganic, plant-usable forms. In many cases, much of the nitrogen is consumed by the organisms, further delaying its plant availability.

This research demonstrates that mycorrhizal fungi allow their plant hosts to bypass this process, implementing quick and effective access to organic nitrogen sources. What this means to the farmer is that utilizing mycorrhizal fungi, naturally occurring and introduced sources of organic nitrogen (such as found in fish-based fertilizers, green manures, and compost) can provide a readily available source of nitrogen to promote crop growth and enhance yields.

In addition to phosphorus and nitrogen, the mass of hyphal filaments in the soil surrounding mycorrhizae-colonized roots is also capable of mobilizing an array of other important plant nutrients, including calcium, iron, magnesium, and critical micro-nutrients such as manganese, zinc, and copper. Just as a lack of vitamins can impair human or animal health, crop yields and forage production are sometimes limited by insufficient supplies of these minor- and micro-nutrients, even when N-P-K is abundant.

Mycorrhizae’s ubiquitous presence throughout the surrounding soil can access these relatively scarce resources and, in many cases, can release them from insoluble compounds via the production of specialized enzymes. The management of micro-nutrients is becoming increasingly recognized as an important component of modern cropping science. Mycorrhizal fungi can serve as a useful tool to ensure that both natural and introduced sources of these nutrients are transferred efficiently from the soil to the plant.

When moisture becomes limiting in a dryland period the mycorrhizal plant utilizes the water stored in root cell vesicles.

Help find water

Mycorrhizae’s significant assistance with nutrient uptake is important, but it is not the only crop-enhancing benefit offered by these amazing fungi. Another valuable feature is water management. The expanded and enormous absorptive surface area connected to the roots is going to ensure that nearly all moisture in a plant’s surrounding soil is accessed. But what then? Once the soil is dry, how can the plant survive?

Mycorrhizae provide a mechanism inside the root cells that addresses this problem. When a root cell becomes colonized by a mycorrhizal fungus, a special shared organ called a vesicle grows inside the root cell. The vesicle is essentially a storage container for water and dissolved nutrients that can be utilized in times of deficiencies, such as drought periods.

When moisture and nutrients are abundant in the soil, surplus supplies are stored in the vesicle. When moisture and/or nutrient shortages occur, the plant begins to utilize the resources stored in the vesicles to avoid stress for extended periods – often weeks or even months longer than non-mycorrhizal plants.

When moisture or nutrients again become available, the plant is able to return to normal, healthy respiration and growth without shock or other negative symptoms. Of course, the reservoir provided by the vesicle cannot last indefinitely and the plant will suffer stress and ultimately death if sufficient moisture or nutrients remain unavailable for too long.

However, in most cases the extra non-stressed time provided via the vesicle allows the plant to survive until the next rainfall. This is great news for the dryland farmer. Australia’s recent excessive rainfall notwithstanding, drought is a serious risk encountered by all dryland farmers. Although not infallible, mycorrhiza inoculation offers inexpensive crop insurance as one of its many benefits.

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Our soils, our future


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.


Fig.1. Current ‘best practice’. Chemically based zero-till farming lacks essential requirements for biological N-fixing, sequestration of humified soil carbon, and building of new topsoil.

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.

Fig.2. The ‘new face of agriculture. Annual grain crop direct-drilled without herbicide into dormant perennial groundcover enhances plant-microbial associations, vastly improves rates of biological N fixation, stimulates nutrient cycling, facilitates sequestration of highly stable, humified soil carbon, and promotes the formation of new topsoil.

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.

Fig. 3. Modern machinery is well suited to sowing annual grain crops into dormant perennial groundcover, a technique known as perennial cover cropping.

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).

Fig 4. Emerging wheat crop one month after sowing into the dormant perennial pasture. Large volumes of soluble carbon are fixed in green leaves during photosynthesis, transferred to roots, and thence to soils via the hyphae of mycorrhizal fungi. After grain harvest, the warm-season native perennial pasture will activate and continue the sequestration process, building soil carbon over the summer period.

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.


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Soil Carbon Diamond In The Rough

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.


Loss of carbon leads to degraded farm soil.

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.


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.


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.

Farmer Gerald Wiebe inspects his fall organic rye crop.

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.


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.


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.


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.

Mycorrhizal-inoculated eggplant (left) exhibits increased yield compared to control plots.

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 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.


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.


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.


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.

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Rascal To Remedy Fungus On The Farm

Non-inoculated corn crop (top) and a mycorrhizal inoculated crop (bottom).

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.


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.

Phytophthora, the infectious agent that caused the infamous Irish Potato Blight, is responsible for the losses in this pepper crop.

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.


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.

Mycorrhizal cultures in Petri dishes excrete the enzyme phosphatase producing the halo effect of dissolved insoluble phosphorus compounds.


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.


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.


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.

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The Real Dirt On Soil

Understanding Native Soils

Figure 1. Del Gates, North Dakota farmer treated sever an I thousand acres and increased yields of wheat and flax using a mycorrhizal inoculant.

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.
Figure 2. Filaments of mycorrhizal fungi extract moisture and nutrients from the soil.

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.

Figure3.Onion field. Left area inoculated with mycorrhizal fungi. Right area not inoculated.

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.

Figure 4. Endomycorrhizal spores.

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.

Beets, broccoli, cabbage, spinach, and canola do not respond to mycorrhizal inoculation.

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.

Figure 5. Roots penetrate deep into well-aggregated soil following inoculation with mycorrhizal fungi on a farm in Manitoba, Canada.

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 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?

Figure 6. Tiny mycorrhizal filaments date from the young roots of the mycorrhizal-coated seed.

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.


Healthy profitable soil is alive.

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”.

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The Back Forty Down Under: Adapting Farming to Climate Variability

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.


Holistically grazed land (left) compared to set-stocked neighbor’s paddock (right), southern Victoria, Australia, April 2009. There has been no fertilizer used on the holistically grazed property for nine years.

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.

The well grassed area on the left has good infiltration compared to the overgrazed area on the right, which has lost soil carbon and soil water-holding capacity. Rainfall that cannot infiltrate simply sits on top of the ground and evaporates.

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.

The dark coloured carbon sequestered around the roots of perennial grasses is readily observed in light coloured soils.

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.

Vertical stacking. Oats sown into perennial native pasture yield grain plus grazing from the same piece of land. Cropped paddock showing the summer-green perennial pasture beneath a harvested strip of winter oats, sown between alleys of tagasaste.

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.


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.

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Mycorrhizae – Four Species is Better than One

In 1968, one of the most classic rock ‘n roll bands of all time, Three Dog Night, released the song titled “One”. The first line of the song is, “One is the loneliest number that you’ll ever do.” These lyrics were written when the song’s author tried to call a friend and he got a busy signal. The author was alone.

The science behind using a single species of mycorrhizae versus a blend of mycorrhizae species is similar to the message of the song, one (using a single species) is a lonely number.

Several companies on the market offer a single species mycorrhizal inoculant product to their customers. These products are often offered as either a component of a growing mix or are sold separately. The single species most commonly offered is Glomus intraradices (aka Rhizophagus irregularis). Products that use a single species are limited in the benefits they can offer the grower. The use of multiple mycorrhizal species opens the door to more benefits to the plant, the grower, the retailer, the landscaper, and the home gardener.

Different mycorrhizal species are responsible for different functional benefits to the plant. One host plant can have mycorrhizal associations with a number of different fungal species (even at the same time). The plant turns on and off the mycorrhizal interactions depending on what benefit(s) the mycorrhizae can offer. If the plant has a relationship with only one single species of mycorrhiza, it will only turn on the single species of mycorrhizae when it can benefit from the limited list of benefits the single species can offer. If the plant has relationships with multiple mycorrhizal species, it will turn on the different mycorrhizae more often since the larger offering of mycorrhizal species has a longer list of benefits they can offer to the plant. Simply said, more species of mycorrhizae can offer more potential benefits to the plant.

This point is best illustrated in a case study involving high levels of phosphorous in a growing media. When the phosphorous levels are high, which is often the case in many growing protocols, Glomus intraradices (Rhizophagus irregularis) will shut down and stop offering benefits to the plant. When these same plants are offered relationships with the four species consortium of mycorrhizae at the same high phosphorous levels, one or more of the mycorrhizae will continue to function and provide benefits to the plant beyond increasing phosphorous availability.

A typical greenhouse or nursery grows a wide variety of crops and many of these crops have different crop times. An additional benefit of using multiples species of mycorrhizae is that each species of mycorrhizae colonizes the roots at a different speed. If you only use one species of mycorrhizae, you only get one speed of colonization. Using the BioStim consortium increases the speed of colonization between the plant and the mycorrhizae. Also, each mycorrhizal species colonizes with a plant to a different extent. More colonization by one mycorrhizal species with a plant is not ideal. Colonization by multiple mycorrhizal species offers the plant the most options and the greatest potential for benefits.

Many environmental factors impact a plant during its production in a greenhouse or nursery that can make a difference in the plant’s long-term success. A plant’s rhizosphere is in a state of constant flux. Changes occur in soil moisture, nutrient availability (particularly phosphorus), soil pH, and soil temperature daily and seasonally in the production environment. Different species dominate under different ecological conditions. When a grower uses only one species of mycorrhizae they limit the plant’s ability to respond to these abiotic changes during production. The utilization of a four-species mycorrhizal blend allows plants to respond more positively over a wider range of environmental conditions.

Plants have a lot of internal variables. A plant’s phenology can be a factor in which mycorrhizae species is more attractive to the plant. Since horticulturalists could be treating plants with mycorrhizae during propagation, production, at landscape installation, or in a finished container, it is best to have the maximum number of mycorrhizal benefits to offer the plant if you want a greater chance for success.

Mycorrhizal fungi species complement each other – rarely would you find a single species in nature. Plants in nature recognize that mycorrhizal diversity increases their chance for success.

When selecting a mycorrhizal inoculant product offering to include in your operations, just remember the saying “There is strength in numbers”. The MycoGold product allows you to have “strength in numbers”.


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Soil Life and Carbon

Answers to Global Warming in Our ‘Root Cellar’

The root system of a rye crop inoculated with compost tea and mycorrhizal fungi — this area is rich in feeder roots, soil organisms, and soil carbon.

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.


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.

Endomycorrhizal spores such as these are deposited beneath the soil surface and do not rapidly recolonize agricultural sites once they have been lost.

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.

Mycorrhizal filaments in the soil extract nutrients and water and leave deposits of carbon-rich glomalin.

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.


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.

A granular mycorrhizal inoculant (left) and a mycorrhizal inoculant coating on wheat seed.

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.


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.


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.

A glomalin-rich soil inoculated with beneficial soil organisms.


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.


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.