Agricultural soils are among the planet’s largest reservoirs of carbon and hold significant potential for expanded carbon sequestration, experts say.

 

Difficulties in measuring and monitoring changes in soil carbon stocks to date have limited efforts to take advantage of the significant mitigation potential of soils, which is one reason the Australian government has hesitated to cover soil carbon under the CPRS.

 

But improvements in technology and an anticipated increase in demand for carbon sequestration beyond what can be currently met by more commonly utilised carbon sequestration mechanisms, such as forestry, are likely to lead to a rethinking of current policies.

 

Dr. Rattan Lal, a professor at Ohio State University, said at the Carbon Farming Conference in Orange, New South Wales in mid-November, that in order to commoditise carbon, a realistic value must be established that reflects its value to farmers and society, as reported by Stock and Land.

 

Leading soil scientists have further said that carbon trading systems must be careful not to undervalue soil carbon, because the true productivity value of soil carbon to farmers may be hundreds of dollars per tonne.

 

Initial estimates of carbon’s starting value under the CRPS are about $20 per tonne.

 

Yet when Dr. Lal looked at humus, or soils with high levels of organic carbon, and teased out the nutrients and water typically held within a kilogram, he arrived a value of US$250 a tonne on today’s prices.

 

Farmers – and society at large – also benefit from the fact that such soils are resistant to erosion, deliver less pollution to waterways, help biodegrade chemical pollutants and buffer climatic extremes, Dr. Lal reportedly said.

“Whether the trading process can provide farmers with all of that value remains to be seen,” he said. “Undervaluing a resource can lead to its abuse.”