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Farming the climate

By Jeffrey Parr and Leigh Sullivan - posted Tuesday, 20 February 2007

We have recently discovered that a process which occurs naturally in plants could play an important role in countering CO2 emissions and global warming. This process is termed plantstone carbon - also referred to as phytolith occluded carbon.

Plantstone carbon is estimated to currently extract 300 million tones of CO2 a year from the atmosphere and to store this carbon securely in the soil for thousands of years. We believe the rate of this natural process could be readily accelerated many times by the adoption of simple agricultural practices.

Plantstones form as microscopic grains of silica in plant leaves particularly in grass-based pastures and crops such as sugar cane and wheat. During plant growth a small proportion of organic carbon becomes encapsulated within these silica grains. Regardless of whether the plant dies, burns or is harvested, the carbon entrapped in the plantstone is highly resistant to decomposition. Therefore, unlike most plant matter which readily decomposes in soil returning CO2 to the atmosphere, the carbon in plantstones effectively removes CO2 from the atmosphere for millenia.


It seems clear that this process, if incorporated into agricultural crops and crop choice decisions on land under active vegetation management, could make a major contribution to lessening atmospheric CO2 concentrations.

Our research into crop plantstone interactions has shown that different plant types produce greatly varying amounts of plantstone carbon. Some crops have been shown to produce over 100 times more plantstone carbon than others. Moreover, varieties within a single crop type such as sugar cane, have been found to produce widely differing quantities of plantstone carbon. This indicates that the farmer’s choice of crop type and variety can have a considerable impact on the amount of CO2 extracted from the atmosphere and securely stored in the soil within planstones.

If Australia adopts an appropriate carbon trading system it will provide a real incentive to Australian farmers to adopt high plantstone yielding crops. This would generate additional farm income without incurring either additional costs or crop yield penalties, or detracting from existing farm income streams.

One of the major advantages of this new technology over previous technologies proposed for use in agriculture is that the quantification of the plantstone carbon produced by a crop is inexpensive. This advantage overcomes a major limitation of previous methods for agriculture where the cost of providing accurate quantification of the amounts of additional carbon stored in the soil arising from land management improvements greatly outweighed the value of those additional quantities of soil carbon.

Governments all round the world are presently investigating and encouraging practices that reduce CO2 emissions in industry and the community. These need to recognise innovative and cost-effective ways of capturing CO2 that can be readily incorporated into farming systems.

As an indication of the importance of this research, the Australian Research Council Discovery Grant Program has funded further development during 2007-2009. We firmly expect that as a result of this work, plantstone carbon research will reach industries such as forestry, horticulture, mining and the rehabilitation of salt affected land, as well as crops such as wheat, barley, sugarcane and maize, as well as pastures.


Plantstone carbon research is emerging as one of the most promising and exciting new tools for countering global CO2 emissions. It provides land managers with the opportunity to play an even greater role in the fight against global warming and climate change - and to earn extra income for so doing. It can be adopted as easily as switching crop type or variety to be grown.

Furthermore, it is likely that given appropriate incentives such as those provided by carbon trading systems, future crops would be bred for their carbon-retention qualities as well as the normal attributes which farmers seek, such as yield, disease and drought resistance, quality and so on.

This is an Australian discovery and it offers this country chance to get on the front foot, globally, in the climate change issue.

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First published in Australian R&D Review on February 7, 2007.  It is republished in collaboration with ScienceAlert, the only news website dedicated to Australasian science.

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About the Authors

Dr Jeff Parr is a Postdoctoral Fellow at the School of Environmental Science and Management at Southern Cross University. Jeffs unique area of research is plant silica relationships and soil carbon sequestration.

Leigh Sullivan is Professor at the School of Environmental Science and Management at Southern Cross University.

Creative Commons LicenseThis work is licensed under a Creative Commons License.

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