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Carbon Farming: there’s more to measure than carbon

Andrew Gulliver

Custom Composts, Nambeelup, Western Australia, www.customcomposts.com.au

Abstract

Recently soil carbon has become fashionable. Sustainable farming practices have valued and managed carbon in the soil for centuries. Some farming practices reduce soil carbon with consequent declines in productivity and soil resilience. Soil carbon is an important indicator of soil health. It is only a symptom of soil management practice and not the cause of good soil health. Adding carbon alone will not magically transform soils.

Other factors can be measured such as farming inputs. It can be argued that focussing on more efficient and effective use of inputs is far easier to measure and that building soil organic carbon will be a consequence. This paper will consider sustainable farming practices and what we might measure at the farm level.

Other fundamental questions arise such as the protection of productive soil resources and the important role they play in thriving rural communities and the provision of food security for nations. How do we measure the social and environmental benefits of a productive soil resource? The link to the current debate on climate change will also be explored. Finally, the beneficial recycling of organic wastes and ‘closing the loop’ will be discussed.

This paper seeks to provide a broader perspective and context within which to discuss ‘soil carbon’.

Key Words

Soil health, sustainability, climate change and recycling wastes

Introduction

Start with a bigger picture

In 1937 Franklin D Roosevelt wrote a letter to State Governors on a Uniform Soil Conservation Law and said;

“The nation that destroys its soil destroys itself.”

This quote underscores the vital role that soils play in the health and welfare of sustainable societies. Soils and communities are linked. The following steps in logic demonstrate this;

  • Manage the soil
  • Maintain or increase soil carbon
  • Improve soil structure
  • More efficient use of water resources and other inputs
  • Improved soil fertility
  • Profitable enterprises
  • ‘Healthy’ farm families
  • Thriving and prosperous rural communities
  • Ability to contribute to sustainable societies

This links the management of our natural resources to the social well-being of our communities. If you like, the stewardship of our natural capital is linked to the building of social capital.

Good farming practice also contributes to a range of ecosystem services, including; less erosion and soil loss, reduced salinity and protection of biodiversity.

Cause and Effect

What role does the measurement of soil carbon play in this scenario? Is it a cause of good outcomes or an effect of good practice? Is it the practice we should be measuring or the soil carbon?

Policy perspective

The national debate about soil carbon is at risk of being distracted by a discussion about measurement techniques for soil carbon. Policy decisions may be delayed due to a perception that we need precise measurement techniques. This could lead to a failure to act.

Australia, unlike other developed nations, does not have a national soil protection policy or dedicated agency. A policy discussion paper was released last year (Campbell, 2008). A soil protection policy would inform and support other policies such as land use planning and community health (through food quality). Today we are concerned with the debate about global warming. In the future we will be consumed by the notion of food security. By 2050 the world will have to feed double the current population using existing agricultural land, or less if land is lost from food production to energy production.

Managing soil carbon is one way of addressing all of these challenges. We urgently need a national policy.

How does soil carbon relate to climate change?

A simple view of carbon cycling

The amount of carbon in the world is fixed and cycles around the air, sea, soil and vegetation. The ‘greenhouse’ effect is caused by the cycle getting out of balance and relatively more carbon (as carbon dioxide) is housed in the atmosphere. There is roughly four times more carbon tied up in soils and vegetation than there is in the atmosphere.

Photosynthesis cycles carbon out of the air and sequesters it into the plant and then into the soil. ‘Labile’ carbon in the soil is cycled quickly – it provides an important energy source for biological processes in a healthy soil. Stable forms, such as humus, can last hundreds of years or more.

Humus is the ‘powerhouse’ of the soil providing food and shelter for microbiological activity and a buffer against changes in moisture, pH, nutrient and chemical levels. Humus is a foundation stone for resilient soils – soils which can absorb shocks and recover quickly.

Some farming practices reduce soil carbon with consequent declines in productivity and soil resilience. Low carbon levels are both an issue and an opportunity for Australian soils. The use of fossil fuel-dependent fertilisers and pesticides adds to the carbon footprint of agriculture.

Conversely, there are 5.5 billion hectares of agricultural soils managed by farmers globally. These soils have the capacity to absorb a significant proportion of our global carbon dioxide emissions for years to come.

The legacy load of carbon dioxide and ‘Carbon Farming’

Industrialised society has been burning fossil fuels and emitting carbon dioxide at an increasing rate for over 100 years. If we stopped all carbon dioxide emissions today then this legacy load is still likely to have an effect on climate.

Farming and photosynthesis are the only technologies available today that can address the legacy load. Emerging technologies will not be proven or have enough capacity within sufficient time to have the same effect as farming. Hence the term ‘carbon farming’ to describe methods to encourage building of soil carbon levels.

Dr Rattan Lal, International Panel on Climate Change member puts it simply;

“Carbon sequestration in soil and vegetation is a bridge to the future.
It buys us time while alternatives to fossil fuel take effect”

Australia’s own Garnaut Report also mentions soil carbon;

“The most significant opportunities may be in the area of soil carbon sequestration”.

Why carbon farming and how?

‘Carbon Farming’ works and has immediate effect and multiple benefits. Increasing soil carbon addresses the impacts of climate change and not just the reduction of emissions. The ‘buffering’ effect creates a soil that is ‘climate-ready’, allowing farmers to better manage possible changed climate scenarios in the future.

The looming threat of both peak oil and peak phosphorus in coming decades, which will affect the availability and cost of fertilisers and pesticides, will drive us to develop more efficient ways of using expensive farm inputs. A resilient soil will make better use of these inputs and of scarce water resources.

Improved soil performance allows farmers an opportunity to mitigate increased costs due to proposed carbon trading schemes. Agriculture is ‘in’ the emissions trading scheme whether or not it wants to be – via cost effects on farm inputs.

Thriving and prosperous rural communities will become even more important in the future. Soil health and productivity will underpin the health of these communities and the society they are part of. The management of environmental degradation (erosion, salinity) are features of past practice that future communities will have to address. We will need ‘resilient’ communities (that can withstand shock and recover quickly).

A growing world population will demand more food and fibre. Carbon farming will build soil health and improve soil fertility, resilience and productivity.

Given the imperative to feed the burgeoning world population this is something we should be doing anyway!

Carbon farming is not new. It is a consequence of many existing recognised farming systems, such as;

  • Time-controlled grazing management
  • Minimum tillage
  • No-till farming
  • Precision agriculture
  • Pasture cropping
  • Natural sequence farming
  • Biological farming
  • Organic farming
  • Biodynamic farming

A farmer could be forgiven for being confused. Today’s farmer will assess a range of techniques and select those that suit his situation and capacity.

Australian farmers are innovative and have demonstrated the ability to adapt. Farming techniques that sequester carbon in the soil are known. There is a wider ‘public good’ attached to the responsible management of our land resources. It makes sense to provide incentives to change behaviour and encourage stewardship and improvement of our natural resources. Most farmers take their ‘duty of care’, as stewards of the land, seriously. The urban population is disconnected from the land and is unaware of the importance of the situation. Ultimately there must be a policy framework that values and protects key productive land.

A standardised set of measurements could provide a useful management tool for gauging progress and comparing farms and farming systems – although the availability of the ‘tool’ should not delay the implementation of good practice.

The current policy debate in Australia revolves around a carbon trading scheme that is now termed a ‘pollution reduction scheme’. This may reduce but will not prevent emissions from major polluters. It does not address the legacy load and agriculture is not included. Agriculture is seen as ‘too hard to measure’ and will be reviewed in 2013.

The error is clear to see – agriculture provides the best chance to rapidly implement measures to mitigate the rise of carbon dioxide at the lowest cost to the government and the community. The additional benefits in productivity, food security and environmental services are reason enough to make the policy change anyway.

Sustainable farming and organic waste management

What is sustainable farming and how do we measure it?

The three basic principles of sustainability for any business can be simply expressed as “Be financially viable, environmentally responsible and socially acceptable.”

For pragmatic farmers these principles can be translated into “Be more efficient in use of energy and water”. These can be measured as production per unit of:

Energy

  • Nitrogen
  • Other artificial fertilisers
  • Pesticides
  • Diesel fuel (and other energy) and

Water

  • Irrigated water and/or
  • Natural rainfall

Farming methods that reduce and/or make more efficient use of these inputs are likely to result in increased soil carbon. These inputs are easy to measure and manage. Perhaps “there’s more to measure than carbon”?

Organic waste management and ‘Closing the Loop’

The movement of food and fibre from farming land to concentrated population centres is a one-way flow of carbon and nutrients. The disposal of wastes from urban centres creates a cost burden and environmental hazards with the potential to add to global warming through the emission of greenhouse gases from landfill.

The fertilisers that farmers rely on are produced from fossil fuel or are mined from depleting resources.

Whilst ‘recycling’ policy ‘pushes’ organic waste from landfill this has not been balanced by equivalent policy aimed at creating market ‘pull’ to re-use these recycled waste products. There is a disconnection between the urban population and the source of its food. Consequently society does not value agriculture or recognise the important potential linkages between the city and the soil. Some communities have successfully embraced “City to Soil” recycling programmes. National and State waste policies have not yet addressed this imbalance and opportunity.

Why compost?

Recycling unprocessed organic wastes has been practiced in the past. It carries the biological risk of transferring plant pests, weeds and disease. Additionally there is a risk of leaching of soluble nutrients with consequent effects on ground water and off-site pollution.

Composting of organic wastes pasteurises the product to eliminate the biological risk. The composting process stabilises the nutrients and organic matter to produce a high humus soil amendment.

Compost is a tool in soil management and fertility programmes. It helps to stimulate soil biological activity whilst other changes to farming practice take effect. The most cost-effective way to sequester carbon in the soil may be to use the power of the sun and photosynthesis. This is not always possible or practical and compost provides an option to start and/or supplement the carbon farming process.

Important benefits of compost include improved humus levels, cation exchange capacity, moisture retention, nutrient retention and more effective use of expensive fertilisers. Compost will also improve biological soil health leading to higher populations of beneficial soil microbes, better nutrient uptake, disease suppression and improved soil and plant health. Compost can also contribute significant levels of nutrients and trace elements in a slow release form.

Other applications for compost include rehabilitation, salinity, stabilisation and erosion control projects.

Many products make similar claims and do have good cation exchange and water holding capacity. Importantly, carbon in the form of compost delivers energy to the soil. It is this combination of nutrients, energy and water that drives soil processes to create healthy soils. The combination stimulates microbial activity and fosters nutrient cycling in the soil.

The increased microbial biomass produces exudates that act as glue and hold soil particles together. These soil aggregates give the soil structure and reduce soil density providing easier access for water and root penetration. Compost will also increase water holding capacity of the soil. This increased capacity combined with greater penetration (i.e. less run off) of water results in more water stored in a given soil volume.

Compost effectively acts as a moisture and nutrient ‘sponge’ in the soil. More efficient use of irrigated water or natural rainfall results in less plant stress between watering events. The increased cation exchange capacity also retains nutrients and releases them as the plant needs them – resulting in savings on expensive fertilisers.

These features and benefits have all been extensively tested. A major difference between compost and other technologies is that composting technologies are available and proven today.

Nationally organic recyclers are in a position to deliver and spread at least 2 million tonnes of quality, fit for purpose, composts and mulches on agricultural land each year almost immediately. The annual carbon sequestered and abated by such a plan would be at least 4.5 million tonnes carbon dioxide equivalent per annum. This is a conservative estimate that does not consider the longer term soil carbon sequestration resulting from improved soil health. Additional carbon sequestration benefits rely, at least in part, on growers adopting appropriate land management practices in conjunction with application of compost.

Compost only costs $50 - $100 per tonne to produce and is immediately available. This makes compost a cost effective and immediate option to abate and sequester carbon.

Conclusion

The current policy debate in Australia revolves around a carbon trading scheme that is now termed a ‘pollution reduction scheme’. This may reduce but will not prevent emissions from major polluters. It does not address the legacy load and agriculture is not included. Agriculture is seen as ‘too hard to measure’ and will be reviewed in 2013.

The error is clear to see – agriculture provides the best chance to rapidly implement measures to mitigate the rise of carbon dioxide at the lowest cost to the government and the community. The additional benefits in food security and environmental services are reason enough to make the change anyway.

Three key learnings:

  • Remember the goal; don’t get too distracted by a particular methodology.
  • Good policy creates an environment where good practice prospers – but we should implement good practice anyway
  • Society needs to value soil more highly and reflect this with good policy and practice.

References

Many of the concepts in this paper are condensed from the policy discussion paper released last year:

Campbell A (2008) Managing Australia's Soils: A Policy Discussion Paper. Prepared for the National Committee on Soil and Terrain (NCST) through the Natural Resource Management Ministerial Council (NRMMC).

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