Carbon Research
Carbon is one of the most talked about issues in the world since 2008 as the climate change topic has taken centre stage. Governments, urban communities, farm lobby groups, scientists and farmers want to know what it means and what they can do about it. And it is about time as this is the most important single issue facing the future of agriculture.
Carbon is the building block of all things living and dead, that is, the dead and living grass, trees, microbes, animals and us. All life shares carbon as a building block. Even the coal that is being dug up by the millions of tonnes from Qld and NSW, the oil and all agricultural crops are formed from carbon chains.
See the influence Holistic Management has on the levels of soil carbon.
Interesting Outcomes in a Comparison of Biodynamic and Conventionally Managed Soils
What happens during Composting?
The Carbon Cycle
Now, the carbon cycle is the big talking point. This is simply the amount of carbon in the atmosphere, compared to the amount in our oceans, the amount in our soils and the amount in other terrestrial based resources (vegetation etc). Carbon is said to cycle from the atmosphere as gases (mostly as CO2 or carbon dioxide and CH4 methane) to various sinks (ocean and soil) and back into the atmosphere again. The total amount of carbon on earth is fixed, we cannot create more and we cannot remove carbon from the earth's system. Carbon can be found as a gas, and in solid and liquid forms, but the total amount of carbon on earth always remains the same. The problem comes when too much of it remains in the atmosphere and this is said to be the major link to climate change. Whether you agree with the climate change model or not it doesn't matter because the real issue is our soils are becoming depleted of carbon.
There are two groups of carbon, the old carbon which was laid down thousands of years ago (now being mined) and the new carbon which is being cycled yearly from soil to plant to atmosphere. Some of the problem is being created by the resource industries mining old carbon for urbanisation, some is simply by the increasing populations and modern technologies and some is being caused by agricultural practices. There are three forms of carbon:
- living - soil biology, earthworms and plant roots
- labile - decaying plant and animal material of the once living component
- stable - charcoal, humus and glomalin
The term total soil carbon is generally referring to a combination of labile and stable carbon fractions.
Carbon to a Farmer and Grazier
Photosynthesis is a process used by plants and other organisms to convert Carbon from the atmosphere via the use of sunlight energy captured from the sun into chemical energy (carbon compounds) that are used to produce more cells, develop root reserves and to exude into the soil to feed micro-organisms. This exudation process provides up to 21% of all carbon from photosynthesis for microbial activity and to bolster carbon reserves in the soil. Algae and cyanobacteria also photosynthesise carbon. In all, photosynthetic organisms convert around 100–115 thousand million metric tons of carbon into biomass per year.
All plants photosynthesise carbon and all crops have the ability to sequester carbon. A well managed pasture and cropping program will increase the soil carbon reserves, while a poorly managed program will deplete these reserves. Since 1788, it has been estimated that we have depleted our reserves by 50% and 80% of starting levels. That means if we began with 5% SOC, we will now have 1% - 2.5% SOC.
All ruminant animals emit methane which has a CO2 equivalent of 300. It is far more potent in the atmosphere, but also degrades faster. It is important that animals grow as efficiently as possible and so will emit less methane during their lifetime and add less to the atmosphere.
Agriculture has four areas where they can impact the carbon cycle:
- Sequestering carbon in vegetation - The key strategy for storing carbon in vegetation is to establish tree lots.
- Sequestering Soil Organic Carbon - The use of specific strategies will enable farmers to store more carbon in soils. This area is being heavily researched to ascertain which strategies are most successful
- Reduce livestock emissions of methane - all ruminant livestock emit 250 - 500 litres of methane daily as a part of the respiratory process. A large part of these CO2 emissions would also be emitted by microbes and plants even if livestock were not consuming them. A number of strategies have been discussed including improved feed efficiency, improved pastures, altering rumen flora. This area is being researched to ascertain which strategies are most appropriate.
- Reduce methane emissions from intensive animal production - this would include effluent ponds etc.
Now the reason why agriculture is so important is because farmers/ graziers control the majority of animals and land which can sequester carbon and reduce methane emissions. There are loads of numbers being added to the argument and lots of science going on right now. However, carbon in our soils varies from 1 metre to the next across the landscape and from the top 10 cm to 30 cm and reduces the deeper you go. It also depends on if a green plant is growing or not and so is difficult to benchmark. This is the first major area of research - getting good methodology to measure carbon accurately.
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