Jones, C. E (2006) ‘Healthy Soils through Communication’ Symposium, Federation of Biological Farmers Inc., Seymour, Vic, 16-17 August 2006

“The real voyage of discovery consists not in seeking new landscapes but in having new eyes” [Marcel Proust]

Imagine how farming would be if all agricultural soils were magnificent. Full of energy. Brimming with life that we could hear, see, smell and ‘feel’? When we nourish soils with purpose, passion and pleasure, soil life responds in kind. As above, so below. When you look at your soil, you see your management reflected. We all want soils to be ‘healthy’. But where to start?

It is life that gives soil its structure. It is life that provides fertility and balanced nutrition. It is life that retains soil moisture, restoring water balance and reversing the effects of dryland salinity. It is life that retains carbon and nitrogen from the atmosphere and balances the greenhouse equation.

The fundamental question is therefore “how do we get life back into soil?”

CARBON is the basic building block for all life on - and in - the earth. We cannot live without it. Neither can our soils. Vibrant, living soils also require air and water. But these inclusions cannot be retained in the absence of good soil structure, which requires soil carbon. Carbon is the driver for every aspect of soil health and soil function - the MASTER KEY to every door.

Carbon (C) provides the structural basis for thousands of different compounds. It is so common, we take it for granted. We often take hydrogen (H) and oxygen (O) for granted too - but where would we be without H 2O - our precious, life sustaining water? The significance of soil water is becoming more apparent as we lose soil carbon. Low soil moisture and low levels of soil organic carbon go hand in hand.

An understanding of the role of carbon in soils and of the balance of gases in our atmosphere, is essential to our understanding of life on earth. Atmospheric carbon is an extremely valuable resource. When sequestered in topsoil as organic carbon, it brings with it a wealth of environmental, productivity and quality of life benefits.

Sadly, around 50 – 80% of the organic carbon that was once in the topsoil has been lost to the atmosphere over the last 150 years or so, due to our failure to take care of the earth as a living thing. By inference, degraded soils have the potential to store up to 5 times more organic carbon in their surface layers than they currently hold, provided we change the way we manage the land.

Anything that causes bare ground results in the loss of organic carbon. Even conventional afforestation and reforestation practices result in net losses in soil carbon for several decades, due to the lack of groundcover under the trees. If bare earth is produced by chemical or mechanical means, we add insult to injury by burning fossil carbon and adding that to the atmosphere as well.

The rusty tank syndrome

Our thinking about soil is restricted by the terms of reference. We measure factors like pH, phosphorus, calcium and CEC. We add some numbers. Soil pH 5.8, available phosphorus 2 ppm, or 20 ppm or maybe 200 ppm. What do those numbers mean?

We search for more and more detail. Meanwhile, our soils are trying to tell us that things have gone terribly wrong in the engine room. They’re screaming at us to stop and look. When we learn to read the soil, we see decades of history before our very eyes. Communication with landscapes and soils occurs on many levels.

In matters of soil management, we need to learn to avoid the ‘rusty tank syndrome’. This term was originally coined in relation to corporate structures. The livelihood of individuals within corporations is dependent on them maintaining the corporate image and preserving the status quo. If the structure begins to deteriorate, experts are called in from outside to find where the tank is losing water and to ‘fix the leaks’. There’s always someone with a solution to the ‘problem’ - at a price. A rusty spot can be patched up, but soon another will develop, and the tank will again begin to lose water. Another expert is called in. More money is spent. The pattern continues. What is really required is a new structure, but there are too many vested interests in maintaining the old one.

The rusty tank syndrome applies equally well to soils. When soils become dysfunctional, that is, not achieving what we’d like them to achieve, we tend to call the experts in to ‘fix the leaks’. The rusty patches manifest as symptoms ranging from compaction, erosion, falling pH, salinity, low fertility and low water-holding capacity, through to declines in vegetation, biodiversity, productivity, crop health, animal health, landscape function, watershed function and eventually, a loss of vitality in rural communities. The never-ending list of problems is served by a plethora of expert opinion and a surfeit of technological fixes.

But, have you noticed, despite the time and money spent, the tank is still rusty? New leaks continue to appear. Alarmingly, many of what are termed ‘improvements’ corrode the tank’s very foundations. Someone forgot to ask ‘does nature approve?’

If we begin at the beginning and build a new tank, we no longer have to continually run around patching up holes. We CAN manage soil life in such a way as to rebuild the building blocks, that is, to restore carbon-rich soils with sound structure, neutral pH, high natural fertility, high water-holding capacity and so much more. From the soil, all else springs. In our mechanized, technologically oriented world, we tend to overlook this extremely significant fact.

Understanding our soils

In the agricultural context, the health of the landscape is determined by how we RELATE to all of the living things in our care. Not just the four-leggeds, but also the life we can’t see. The microscopic workers on the leaves of plants, in the litter on the soil surface and in and around plant roots. The more leaves, litter and plant roots there are, the larger the workforce of nature’s helpers and the faster we can potentially build new soil. In this unseen world there are thousands of symbiotic relationships and feedback loops. Change one factor and we change them all. All are connected. Every management decision counts.

For these reasons, the simple answer to the question, “carbon, air and water – is that all we need?” is NO.

We need PEOPLE. Inspired, motivated people, working in relationship with each other and with their land to foster an exciting design for a new agriculture. We do not know how this regenerating landscape will ‘look’ - nor do we need to - it will be an evolving work of art. Ecological processes are never static. Our expertise will be directed to understanding process and function in a changing world. Information itself cannot bring about change. ‘Systems’ and ‘recipes’ are doomed to fail.

It is about healing earth gently, with carbon – and people.

How does carbon get into soil?

In the miracle of photosynthesis, which takes place in the chloroplasts of green leaves, carbon dioxide (CO 2) from the air and water (H 2O) from the soil, combine to capture sunlight energy and store it in the form of a simple sugar - glucose (C 6H 12O 6). Through a myriad of chemical reactions, this glucose forms the basis of a great diversity of carbon compounds, including carbohydrates, proteins, organic acids, humic substances, waxes and oils – and historically, our ‘fossil fuels’ coal, oil and gas. We have a great deal for which to thank green leaves!!

The cheapest, most efficient and most beneficial forms of organic carbon for improving microbial activity and soil structure result from the tandem process of photosynthesis followed by the exudation of carbon compounds from the actively growing roots of plants in the Poaceae family (which includes pasture grasses and cereals). Soil carbon additions are governed by the volume of fibrous roots per unit of soil and their rate of growth. The greater the number of active green leaves and active plant roots, the more carbon is captured from the air, translocated through the plant and exuded into soil. It’s as simple as that.

Let us consider two very practical ‘real life’ examples – one relating to broadacre cropping and the other to grazing.

Pasture Cropping

Many of the benefits of Pasture Cropping can be attributed to having perennial pasture grasses and cereals together, side by side in space and time. The 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 stimulate microbial activity.

In this positive feedback loop, CO 2 respired by plant roots and soil microbes, slowly moves upwards through the topsoil and increases the partial pressure of CO 2 beneath the crop/pasture canopy, enhancing photosynthetic potential. As money makes money, so carbon makes carbon - but only when the management is right.

Under conventional cropping regimes, the stimulatory exudates from crop roots are negated by cultivation, bare earth and harsh chemicals. In this scenario, carbon dioxide evolved from soil is lost to the atmosphere. The carbon cycle is broken. Over time, soil carbon levels under conventional cropping often fall to levels where the soil is essentially ‘dead’

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 carbon sequestration in soil is the most potent mechanism available for reducing greenhouse gases and mitigating climate change.

Planned Grazing

Grazing animals, plants, soil biota and soils have co-evolved for over 20 million years, resulting in highly complex - and sensitive - inter-relationships. What are the communication pathways in soil? In what way do living things below ground respond to changes above ground? What are the triggers? How can we incorporate the soil’s needs into grazing management?

Levels of biological activity in soil vary enormously over space and time. They are affected by moisture, temperature, pH, oxygen concentration and the availability of a carbon source (energy). All of these factors are strongly influenced by the way plants are grazed. Of particular interest to this discussion is the supply of carbon compounds to soil biota, in terms of timing, quality and amount.

In a green grass plant, there is generally more nitrogen in the leaves than in the roots, and more carbon in the roots than in the tops. When the leaves are removed by grazing, the plant responds immediately to re-adjust this balance. Some carbon (in the form of soluble carbohydrate) is mobilized to the crown for the production of new leaves, some is lost to the soil as pruned roots and some is actively exuded into the rhizosphere (the soil surrounding plant roots) where it can have profound stimulatory effects on soil biota.

If plants are grazed more-or-less continuously, they will have poorly developed root systems and there will be very little carbon available for injection into the soil at each grazing event. The animal-plant-soil ecosystem will decline to a steady-state equilibrium where not much happens other than further deterioration. Many leaks develop because the soil ‘tank’ is not robust.

When grazing is optimized by ensuring that the most desirable plants (from the animal’s perspective) have recovered sufficiently for their root systems to be well established before re-grazing, the net effect of grazing is an increase in soil carbon (energy) levels.

The carbon exuded from the roots of grazed plants stimulates the rhizosphere flora involved in the acquisition and transfer of nitrogen, phosphorus and other nutrients, assisting rapid regrowth of leaves. This enhances energy and nutrient flows. Appropriately managed grazing also stimulates the microbial production of a wide range of plant growth stimulating substances in soils, including natural hormones, enzymes and vitamins.

The optimization of the grazing process helps to synchronize nutrient mineralisation with plant demands. This reduces losses from the soil ecosystem. Under continuous grazing, particularly in seasonal rainfall environments, the supply and demand for nutrients such as nitrogen rarely match, leading to imbalances and contributing to ‘problems’ such as soil acidity. It is one of nature’s paradoxes that increased levels of soil biological activity not only improve nutrient availability, but also minimize soil nutrient losses and stabilize soil pH.

Eco-agriculture

In addition to using techniques such as Pasture Cropping and Planned Grazing to stimulate plant root exudation, soil carbon levels can also be increased using principles employed in various forms of ecological agriculture, such as biodynamic, organic and biological farming. There is a wide range of practices including the use of cover crops, green manures, mulches, fish and seaweed products, animal manures, recycled greenwaste, biosolids, composts, compost teas, liquid injection, humic substances, microbial stimulants and various combinations thereof.

Irrespective of the method employed, the desired outcome is to stimulate positive feedback loops in the animal-plant-soil ecosystem, resulting in improvements in:-

• biomass of soil organisms
• diversity of soil organisms
• rate of nutrient cycling
• macronutrient (N & P) availability
• trace element (Cu, Zn etc) availability
• proportion of beneficial soil organisms
• disease suppression
• size and number of soil pores
• soil aggregate stability

 Managing the carbon cycle

 Adding organic carbon to soil is one thing. Keeping it there is another. Topsoil is always in a state of dynamic equilibrium with the atmosphere. Carbon additions therefore 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.

A net gain of organic carbon in soils is win-win for plants, animals and people. A net gain of carbon in the atmosphere is lose-lose. Our role, as managers of the carbon cycle, is to ensure that as much carbon as possible is returned to soils and as little as possible goes into the air.

Carbon sources and carbon sinks

In bare paddocks, or cropped or grazed paddocks dominated by annual plants, more carbon will move to the atmosphere than is sequestered. That is, the soil is losing organic carbon and is said to be a SOURCE of atmospheric carbon. This adds substantially to the accumulation of the greenhouse gases responsible for global warming and climate change.

 In cropped or grazed paddocks managed regeneratively, actively forming topsoils behave as carbon SINKS. That is, more carbon is sequestered than is lost, reducing the level of carbon dioxide in the atmosphere. 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 balance the greenhouse equation

Carbon and nitrogen

Nitrogen moves between the atmosphere and the topsoil in similar ways to carbon. The main difference is that the ‘way in’ for atmospheric carbon is via green plants whereas the ‘way in’ for atmospheric nitrogen is soil microbes. Soils acting as net sinks for carbon are usually also acting as net sinks for nitrogen. The flip side is that soils losing carbon are usually losing nitrogen too. Some of this nitrogen loss is in the form of nitrous oxide, a greenhouse gas up to 300 times more potent than carbon dioxide.

Rewarding landholders for farming in ways that build new topsoil and raise levels of soil carbon and nitrogen would have a significant impact on the vitality and productivity of Australia’s rural industries, as well as reducing the levels of greenhouse gases.

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

Carbon credits

The capacity for appropriately managed soils to sequester atmospheric carbon is enormous. The world’s soils hold around twice as much carbon as the atmosphere and almost three times as much carbon as the vegetation. Soil represents the largest carbon sink over which we have control. Improvements in soil carbon levels could be made in all rural areas, whereas the regions suited to carbon sequestration in plantation timber are limited.

If financial incentives in the form of ‘carbon credits’ amounting to several thousand dollars per hectare became the primary focus of primary production, farm enterprises such as meat, wool or grain could become of secondary importance as an income source. This would reduce the potential for destructive farm practices and provide a large incentive for ‘greener’ forms of agriculture.

Any farming practice that improves soil structure is building soil carbon. When soils become light, soft and springy, easier to dig or till and less prone to erosion, waterlogging or dryland salinity - then organic carbon levels are increasing. If soils are becoming more compact, eroded or saline - organic carbon levels are falling.

Water, energy, life, nutrients and profit will increase on-farm as soil organic carbon levels rise. The alternative is evaporation of water, energy, life, nutrients and profit if carbon is mismanaged and goes into the air. It’s about turning carbon loss into carbon gain.

CONCLUSION

 Extraordinary things happen to plants, animals and people when soils are renewed. In any business it’s good business to give the customers what they want. When your soil talks, listen. Healthy soils are not just about carbon, air and water. They are about PEOPLE, including you and me. We’re all in this boat together. Let’s build a good one!!

“The invariable mark of wisdom is to see the miraculous in the common”

[Ralph Waldo Emerson]

………………………………………………………………………………

APPENDIX

Stable soil carbon

Organic carbon moves between various ‘pools’ in the soil, some of which are short lived while others may persist for thousands of years. Glomalin and humic substances are two of the relatively stable forms of soil carbon. Their creation and destruction are strongly influenced by land management.

Glomalin

The relatively recent discovery of glomalin has caused a complete re-examination of what makes up soil organic matter and how we measure it. Glomalin is a glycoprotein (contains both protein and carbohydrate) produced by arbuscular mycorrhizal fungi living on plant roots. Most current soil chemical extraction techniques greatly underestimate the amount of glomalin, which can persist for several decades and may account for one third of the organic carbon stored in agricultural soils.

Prior to the discovery of glomalin, humic acid was thought to be the main contributor to soil carbon. Dr Sara Wright (USDA – ARS) has shown that glomalin contributes about seven times more carbon to total soil organic carbon than do humic acids. This discovery has attracted a great deal of interest from a carbon storage and carbon trading perspective, in addition to the multiple benefits for soil and catchment health.

Glomalin forms on the outer surface of the hyphae of mycorrhizal fungi, which colonize the roots of certain plants. In everyday terms, the more of these roots there are and the more active they are, the more glomalin can be produced. The glomalin molecule also contains quite high levels of iron which are thought to help protect plants from soil pathogens.

Most members of the grass family are excellent hosts for mycorrhizal fungi, with up to 100 metres of microscopic fungi forming per gram of soil under healthy grassland. Enhanced glomalin formation may partly explain the successes of Pasture Cropping and Planned Grazing.

Inhibitory factors for mycorrhizal fungi and glomalin production include bare soil, intensive tillage, the application of phosphorus fertilizer and the presence of plants from the Brassica family, such as canola, turnips, cabbage and broccoli, which do not form mycorrhizal associations.

Humus

There is nothing recent about the discovery of humus, which dates back to Roman times. Despite being the best known of the stable organic fractions in soils, humus has never been clearly defined or understood. Even today, some aspects of the formation, composition, structure and function of the heterogeneous group of high molecular weight humic substances known collectively as ‘humus,’ remains somewhat of a mystery.

One reason is that humus is an integral component of the soil matrix and cannot be successfully isolated for scientific research. Synthetic or extracted humus does NOT have the same properties as humus found naturally within the soil.

There are many theories on the formation of humus, most of which suggest a microbial resynthesis and polymerisation of carbon compounds derived from organic matter. If soil conditions are conducive to biological activity however, levels of humus can increase to a greater extent than would be possible from the weight of organic materials grown or applied. This suggests that microbial stimulation per se may be the factor of greatest importance, with organic matter simply fueling the process.

In healthy soils, stable humic substances can persist for over one thousand years. Practices that destroy soil structure, such as intensive tillage or the application of anhydrous ammonia, result in the loss of humus.

Humic substances have significance above and beyond the relatively long-term sequestration of atmospheric carbon. They are extremely important in terms of pH buffering, inactivation of pesticides and other pollutants, improved plant nutrition and increased water-holding capacity of soil. Humic substances can also effectively ameliorate the symptoms of dryland salinity by chelating salts and stimulating biological activity.

Loss of humus therefore has a highly significant effect on the health and productivity of soil.

Healing earth gently

We once farmed Fields of Eden, we grew our food with style
It’s time to stop, and look, and listen for a while
Earth lying naked and barren
Crying for help without words
Calling so softly for carbon
There is no time now to bargain

Our soils were rich in carbon, life’s treasures flourished there
Then soil health we neglected: earth’s carbon moved to air
Everywhere climates are changing
The future’s becoming unclear
Warming us slowly with carbon
There is no time now to bargain

Healing earth gently with carbon
Restoring the health to the land
Bringing us back Fields of Eden
There is no time now to bargain
Healing earth gently .. with this song

……………………………………………………………..

Further information:

‘Carbon storage in soils – myth or reality?’ Australian Farm Journal, August 2005, pp. 18-21
‘Dollars for soil carbon’ Australian Farm Journal, September 2005. p. 58.
‘Managing the carbon cycle’ Australian Landcare, September 2005, p. 41
‘Smarter farming cuts global warming’ Australian Farm Journal, October 2005, pp. 54-56.
‘Potential for high returns from soil carbon’ Aust Farm Journal, February 2006, pp. 55-58.

‘Managing the Carbon Cycle’ Forums will be held in Kingaroy QLD, 25-26 October 2006, Canberra ACT, 22-23 November 2006 and Katanning WA, 21-22 March 2007. See www.amazingcarbon.com or contact Christine@amazingcarbon.com