This report, published in March 2009 by the Australian government proposes that organic soil carbon can be divided into at least three ‘pools’ according to how fast it breaks down and is replaced. The pools are commonly divided into: fast (e.g. annual), slow (e.g. decadal) and passive (e.g. millennial). For carbon sequestration (long-term storage) and carbon trading purposes, it is especially desirable to increase the total amount of carbon in the pools that break down slowly (e.g. the slow and passive pools).
This report, published in March 2009 by the Australian government proposes that organic soil carbon can be divided into at least three ‘pools’ according to how fast it breaks down and is replaced. The pools are commonly divided into: fast (e.g. annual), slow (e.g. decadal) and passive (e.g. millennial). For carbon sequestration (long-term storage) and carbon trading purposes, it is especially desirable to increase the total amount of carbon in the pools that break down slowly (e.g. the slow and passive pools).
To mitigate greenhouse gases, sequestration of carbon must achieve long-term substantial withdrawal of carbon from the atmosphere, with a low risk of rapid or large-scale leakage. For long-term sequestration to be counted, consistent methods and transparent processes would need to be designed and funded. Methods may be required to efficiently allocate organic soil carbon into the different pools.
The net benefits of carbon sequestration in soils may not be as large as first expected (e.g. due to decomposition) and some processes that increase carbon sequestration may have adverse environmental effects, particularly on biodiversity and ecosystems [my emphasis]. Uncertainties in measurement also mean that it is difficult to bundle organic soil carbon into tradeable units. Changes in land-use or management practices may also release stored organic soil carbon and would need to be considered.
Potential participants in soil carbon trading are likely to require more information on the likely increases in organic soil carbon including the impacts of climate variability and climate change, the effects on associated greenhouse gases and the likely responses of land managers to incentives. Individual land managers will require information and user-friendly tools to help them trade small amounts of carbon over short periods. Further research is warranted into the effects of farming systems on storage and distribution of organic soil carbon and the effects of salinity and acidity on net sequestration of carbon in soils.
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