The world's soils hold three times as much carbon as the atmosphere and over four times as much carbon as the vegetation. With 82% of terrestrial carbon in soil (compared to only 18% in vegetation), soil represents the largest carbon sink over which we have control.
Soil is also the world’s largest store of terrestrial diversity, with over 95% of life forms being underground (that is, only 5% of biodiversity is above ground). Sequestering humified carbon in soils represents a practical, permanent and productive solution to removing excess CO2 from the atmosphere. By adopting regenerative soil-building practices, it is practical, possible and profitable for broadacre cropping and grazing enterprises to record a net sequestration of carbon in the order of 25 tonnes of CO2 per tonne of product sold (after emissions accounted for). Australia’s annual emissions of CO2 are predicted to exceed 600 million tonnes by 2008.
Friable, porous topsoils make it easier for plant roots to grow and for small soil invertebrates to move around. Well-structured soils retain the moisture necessary for microbial activity, nutrient cycling and vigorous plant growth and are less prone to erosion. Soil structure is very fragile and soil aggregates are continually being broken down. An ongoing supply of energy in the form of carbon from the rhizosphere exudates of actively growing plants and, to a lesser extent, decomposing organic materials, enables soil organisms to flourish and produce adequate amounts of the sticky secretions required to maintain soil structure and function. Healthy, chemical-free soils also create appropriate conditions for humification (conversion of soluble carbon to humus), a process which does not occur in most conventionally managed agricultural soils.
Soil is also the world’s largest store of terrestrial diversity, with over 95% of life forms being underground (that is, only 5% of biodiversity is above ground). Sequestering humified carbon in soils represents a practical, permanent and productive solution to removing excess CO2 from the atmosphere. By adopting regenerative soil-building practices, it is practical, possible and profitable for broadacre cropping and grazing enterprises to record a net sequestration of carbon in the order of 25 tonnes of CO2 per tonne of product sold (after emissions accounted for). Australia’s annual emissions of CO2 are predicted to exceed 600 million tonnes by 2008.
Friable, porous topsoils make it easier for plant roots to grow and for small soil invertebrates to move around. Well-structured soils retain the moisture necessary for microbial activity, nutrient cycling and vigorous plant growth and are less prone to erosion. Soil structure is very fragile and soil aggregates are continually being broken down. An ongoing supply of energy in the form of carbon from the rhizosphere exudates of actively growing plants and, to a lesser extent, decomposing organic materials, enables soil organisms to flourish and produce adequate amounts of the sticky secretions required to maintain soil structure and function. Healthy, chemical-free soils also create appropriate conditions for humification (conversion of soluble carbon to humus), a process which does not occur in most conventionally managed agricultural soils.
There is no valid reason for the Australian agricultural sector to be a net emitter of Greenhouse gases.
There are 603 million good reasons for agriculture to be a net sequester of CO2 . It would require only a 0.5% increase in soil carbon on 2% of agricultural land to sequester all Australia’s emissions of carbon dioxide. That is, the annual emissions from all industrial, urban and transport sources could be sequestered in farmland soils if incentive was provided to landholders for this to happen.
Our soils .. Our FutureCHRISTINE JONES:
An overview of the Australian Soil Carbon Accreditation Scheme (ASCAS) is an example of an incentive-based (rather than regulatory) approach. It is a project designed to provide proof of concept that: Rebuilding carbon-rich agricultural soils is the only real productive permanent solution to taking excess carbon dioxide from the atmosphere.
Irrespective of climate change, it would be of enormous economic benefit to the agricultural sector to rebuild soils by implementing practices that increase levels of humified soil carbon and reduce reliance on fossil fuels. Revegetation not Land Clearing: a case for better management of the northern savanna. National Land & Water Resources Audit 2007.
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ABC Landline VIdeo ... Ground Control
Biomass (e.g. the waste left after chaining) can be converted to
charcoal by slow anaerobic burning – a process termed pyrolysis. The agrichar
can then be dug into the soil, or distributed along with pasture seeds and/or
other fertilizer, where it serves a double purpose.
Firstly the carbon is held by the soil for a very long time, and not washed out. The charcoal forms a structure in the soil that encourages life, such as nitrogen-fixing bacteria and other microorganisms. It functions like a soil-based ‘coral reef’. In this way, and in others no doubt yet to be researched, the fertility of biochar treated soil is enhanced – sometimes for hundreds if not thousands of years. The use of biochar in combating climate change has been promoted by luminaries such as Tim Flannery, James Hansen, NASA’s director of the Goddard Institute of Space Studies, and Professor James Lovelock, originator of the Gaia Theory. It also attracted media attention recently with announcements from Opposition leader Malcolm Turnbull who said: “We have an enormous opportunity here in Australia to absorb millions of tonnes of carbon dioxide from the atmosphere, store it safely as carbon, and put it back into the soil and increase the productivity and the health of our own landscape.” |