As unsustainable farming practices steam ahead amid damning climate change predictions, a way to monetise the transfer of carbon to soil has been found.
But a recent report by Lux Research senior analyst Joshua Haslun and research director Sara Olson, Messaging and Reality are Misaligned for Soil Carbon Sequestration, questioned the validity of making money through soil carbon sequestration, and associated farming practices.
Soil carbon sequestration (SCS) involves the transfer of atmospheric carbon dioxide to the soil via plants, plant residues and other organic matter, the report explained.
As plants suck up carbon dioxide from the atmosphere, carbon is transferred into the ground when dead plants decompose.
This turns soil into a carbon sink, while also improving soil quality, storing some atmospheric carbon, and improves the resilience of land to environmental stressors, Haslun and Olson said.
Other carbon sinks are oceans and forests.
According to Ohio State University’s Rattan Lal, between 50% and 70% of the world’s original carbon stock has been lost, mostly due to unsustainable farming.
Research in 2017 suggested farming, which started tens of thousands of years ago, resulted in the loss of over 130 billion tons of carbon.
A significant amount of carbon is stored in the top two metres of soil and over the past 200 years, agricultural practices have done significant damage.
The global agricultural industry accounts for about 50 million square kilometres of soil.
But for how long can the soil store the world’s carbon debt and how much still needs to be learnt about soil carbon sequestration before the planet gives in?
Some researchers have said SCS was essential to solving climate change. The United Nations Environment Programme’s Foresight Brief explained that 23% of the world’s greenhouse gas emissions were due to agriculture, forestry and other land use and pushed for the potential of SCS.
In South Africa, this accounts for 6% to 9% of the greenhouse gas emissions – slightly lower than the global benchmark of 13.5%.
However, according to Olson and Haslun’s report, “SCS is unlikely to be a solution to climate change”. It is clear conservation agriculture must become a priority to keep topsoil fertile and lower carbon emissions before population numbers, and food needs, continue to rise.
Agricultural Research Council soil scientist Corrie Swanepoel said: “There is no simple answer to the question of carbon sequestration as a solution to climate change.”
She said some management practices saw carbon build up in soil in some regions, but it could not be applied across the board.
This was reiterated by SA Environmental Observation Network uLwazi Node acting manager Nicky Allsopp, who said: “Carbon sequestration in agricultural soil is an overoptimistic panacea for climate change, because there is insufficient knowledge on how to apply this in different types of soil, under different climate regimes and agricultural systems.”
Sustainable management systems
A recent ARC study found that carbon was increased in soil when regenerative agriculture was implemented and zero till, multicropping and use of permanent organic mulch was practised.
The study estimated that up to 17% of carbon could be sequestered during a seven-year period.
But great uncertainty still existed around this figure, which could result in complications when monetising the amount of carbon sucked into the soil.
“The problem with monetising things like carbon sequestration in agricultural soils is that this can provide a perverse incentive for people to embark on untested approaches,” Allsopp warned.
Inaccurate agricultural statistics were acknowledged by the department of environmental affairs in Agri SA’s 2017 presentation discussing the implications of carbon tax and an offset system for agriculture.
The report disclosed that significant improvements have been shown in soil carbon storage, but that opportunities still existed in commercial, smallholder and communal systems.
Department of agriculture, forestry and fisheries climate change and disaster management director Dr Ikalafeng Kgakatsi confirmed that while SCS can successfully be achieved around the world, in SA more research was required.
