Dr Christine Jones reveals the secret behind rapid soil carbon storage

Dr Jones—I am the founder of the Australian Soil Carbon Accreditation Scheme and my PhD research was on the chemistry of the carbon compounds that come out of plant roots and into the soil. Soluble carbon entering soil from plant roots is rapidly humified if appropriate microbial associations are in place. This humified carbon is not labile and is not easily lost, as was suggested this morning by Dr Mark Howden. The main pathway for soil to act as a permanent carbon sink is through the perennial grasses and perennial shrubs that have been referred to by Bob Wilson and Tim Wiley this morning. The humification pathway for soil carbon increase is not included in any current models used byCSIRO or other organisations in Australia. I have spent my whole adult life in tertiary education and in working with farmers to find better ways of doing things. Building soil carbon,restoring healthy topsoil and improving resilience and productivity in agriculture equates to winwin—for the atmosphere, for the soil and the Australian economy.
Currently, field days and workshops on soil carbon readily attract 100 to 200 farmers, whereasif we ran field days on soil health we may get 30, and it is always the same ones who turn up. Sowe are accessing a whole lot of farmers who never came to field days before. If a financialincentive were to be provided for farmers to increase their soil carbon, all of Australia’s carbondioxide emissions could be easily and permanently sequestered in soil. Our emissions are predicted to be 603 million tonnes this year. A 0.5 per cent increase in soil carbon, which wouldbe readily achieved under perennial agriculture, on only two per cent of our agricultural landwould sequester 685 million tonnes of carbon dioxide, which is a greater amount than our total national annual emissions. There is no need for the agricultural sector to be a net emitter ofgreenhouse gases. In fact, agriculture provides the only viable and immediately availablesolution to excess carbon dioxide in the atmosphere.All of the major greenhouse gases—carbon dioxide, methane, nitrous oxide and watervapour—are cyclical. The way land is managed has an enormous impact on this cycling process.For example, the amount of water lost as evaporation is directly affected by the amount of carbon and nitrogen sequestered in soil as humus, and that humification pathway is the one thatwe find under perennial agriculture. We do not find that in conventional business-as-usualagriculture. So providing a financial incentive to farmers to increase levels of soil carbon wouldhave a beneficial effect on reducing all four major greenhouse gases.