Carbon
Much is still being learnt in this space, but soils ability to sequester carbon while increasing soil health and function, is worth a deeper look. Carbon stored within soil gives soil it’s fertility and structure, while also increasing soils water holding capacity. In fact, soil organic matter is primarily made up of carbon, with the exchange between plant and soil occurring via mycorrhizal fungi in the rhizosphere (soil surrounding the root). Having a variety of plant species, and therefore root systems, helps to store carbon in different layers in the soil (see above image1).
Within the soil we have two types of carbon.
Organic Carbon:
This type of carbon is derived from living organisms, including plant residues, microbial biomass, and humus, which is the stable fraction of organic matter. Organic carbon is fundamental to soil structure, fertility, and microbial activity. It improves water retention, cation exchange capacity, and provides a reservoir of nutrients for plants and microorganisms. Organic carbon is dynamic, influenced by soil management practices, and subject to processes like decomposition and mineralization. A significant portion of soil organic carbon is found in humus, which is highly resistant to decomposition and can persist in soils for hundreds to thousands of years, sequestering carbon and mitigating climate change.
Inorganic Carbon:
This carbon form consists primarily of carbonates, such as calcium carbonate (CaCO₃) and magnesium carbonate (MgCO₃). Inorganic carbon is commonly found in arid and semi-arid regions where precipitation is low, leading to the accumulation of carbonates. These carbonates can originate from weathering of parent material or from biological processes that lead to the precipitation of carbonates in the soil. Inorganic carbon contributes to soil pH buffering and influences soil physical properties. Unlike organic carbon, inorganic carbon is generally stable and less influenced by short-term soil management practices.
Carbon Farming
Carbon farming aims to increase the amount of carbon sequestered into the soil. The Federal Governments Emissions Reduction Fund is a voluntary scheme that incentivises adopting new agricultural practices and technology. There are a number of ways to participate, with one Australian Carbon Credit Unit (ACCU) earnt per tonne of CO2 stored or saved from becoming an emission. While there is a bit of a process to go through to be registered, an important element is that you need to have a baseline BEFORE you start sequestering, or saving carbon. For more details, please see the Clean Energy Regulator Emissions Reduction Fund website. PTO for details.
First Nations Perspective
There is a global push to decarbonise and replace fossil fuels with renewable energy stored in batteries. This is a reductionist approach to addressing what is a cocktail of global emergencies where carbon in the atmosphere is but one of many pressing concerns pushing civilization as we know it to a precipice.
For example, the metals required to transition will require mining operations to expand at a rate and scale never before seen in human history. These new mines that will supply the metals and rare earths for this transition will predominantly come from the lands of Indigenous people’s, where the last remaining biodiversity hotspots remain, in countries with very few environmental regulations, and no regard for human rights. Indonesian controlled West Papua is an example of all these things.
This is why regenerative agriculture should be looking beyond the farm-gate and asking questions about the broader impacts of doing business. For example, there’s a big transition happening in Australia where the rangelands are being destocked and abandoned to conventional farming practices to be used for carbon credits. The flow on effect from this is a loss of job opportunities in agriculture in these regions, which has broader social ramifications.
Storing carbon in woody vegetation is still a narrow, reductionist approach. Yes, the biomass of trees can hold carbon, but with too many trees there’s a likelihood we’ll start to see massive bushfires as the fire load becomes hazardous. This is also great habitat for feral pests.
First Nations peoples maintained grasslands with fire to ensure the natural environment was healthy, vibrant and diverse. Native grasses have extensive root systems and that sequester carbon through the ongoing process of senescence and renewal. Native grasslands are vital for biodiversity, water infiltration, soil stabilisation, and thrive on Australia’s weathered soils.
Reflective Questions
- What activities are you doing to improve carbon sequestration?
- What activities have you done that are counterproductive to carbon sequestration?
- Consider the First Nations perspective, how does this view match your own? How does it differ?
References
Jansson, C., Faiola, C., Wingler, A., Zhu, X.-G., Kravchenko, A., De Graaff, M.-A., Ogden, A. J., Handakumbura, P. P., Werner, C., & Beckles, D. M. (2021). Crops for carbon farming. Frontiers in Plant Science, 12, 636709.
