Radio Transcript

Welcome to Agritalk

This week we are going to be talking about Soil Carbon.

An awareness of climate change and associated issues has raised expectations of some farmers to the possibility that measurable increases in soil carbon levels will produce a cash value in the future should carbon-trading ventures begin.

Soil carbon levels have long been recognised as an indicator of soil health .

Due to its capability to influence the physical, chemical and biological properties of the soil

Soil Health is a reflection of what we do right in our farming system.

With approximately 76% of Australian soils having less than 1% organic carbon,there should be the ability to increase this level, right?....

Well, maybe…as it also depends on the type of organic matter.

Work conducted by CSIRO scientists Jeff Baldock and Jan Skjemstad have shown that there are two distinct carbon pools in the soil a biologically stable pool of old carbon (dominated by microscopic charcoal fragments) and an ‘active’ carbon pool that is cycled through biological systems in the soil and by crops.

The stable pool is very difficult to add to and can account for 60% of the organic carbon present in Australian soils. The remaining 40% of the organic carbon pool we are able to influence through farm management.

However, in low rainfall environments this is difficult due to crop production being limited due to season and therefore the amount of residues returned to the soil is highly variable.

Soil type is another influencing factor with clay soils being better able to “protect” carbon than predominantly sandy soils.

As you can see, in farming systems carbon sequestration is difficult to measure due to the variability of biological processes and systems.

Whilst aiming for increasing soil carbon levels is still a valid and valuable goal due to
the long recognised benefits of :

• increasing water holding capacity,
• positively influencing the exchange and buffering capacity of the soil,
• increasing aggregation and aggregate stability
• and increasing absorption and infiltration.

It seems that any financial benefits that farmers might realise might be limited (for now).

Future research happening as part of the new Eyre Peninsula Farming System project will help us understand and learn more about the types of carbon present in our farming systems and the importance of organic carbon within our farming systems.

For further information on this story or any edition of Agritalk, please visit www.ruralsolutions.sa.gov.au, click on news, then radio.  You will find a transcript of the program along with lots of handy links to the things discussed.

Information kindly supplied by Liz Guerin, Soils and Land Management Consultant, Rural Solutions SA

back to top