An international team of soil experts says carbon sequestration in soil has the potential to enhance food security and mitigate climate change.
Soil scientist Professor Louis Schipper from the University of Waikato is a member of the 10-strong team that has published findings in the May issue of Nature Climate Change.
The article provides a road map, implications and expected benefits to be gained if carbon can be sequestered by 4 parts per 1000 year on year, which if accomplished would greatly reduce global temperature increases.
“It’s a big ask,” says Professor Schipper, “but I think people are awakening to the idea that carbon in soil is good for soil health and the atmosphere, and if we’re to capture CO2 from the atmosphere then, like a healthy bank account, we’ve got to have more carbon going into the soil than coming out.”
The 4 parts per 1000 initiative is part of the Lima Paris Action Agenda, is supported by the UN Food and Agriculture Organization and connects to the UN’s sustainable development goals.
“Because soil is such an important reservoir of carbon, relatively small changes in the amount of carbon stored in soils could have significant effects on net greenhouse gas emissions,” Professor Schipper says. “The challenge is implementing a programme like this world-wide with varying climates and land uses.”
Carbon makes up about 50% of soil organic matter, and scientists need to know how much carbon each soil type contains, how much land is covered in each soil type and how the amount of soil carbon changes over time.
In New Zealand, scientists use soil sampling and micrometeorological techniques to determine changes in carbon stocks. New Zealand soils have relatively high carbon stocks so maintaining or slightly increasing carbon sequestration from such a high base is a focus of Professor Schipper’s research. He and his colleagues at the University and Landcare Research have been researching grazed pastures including the role of alternative pasture swards and pasture renewal as ways to increase carbon in the soil or avoid losses “to ensure we don’t lose what we’ve got”.
In developing countries in particular, land can be over-used for growing food, feeding livestock, biofuels, home-heating and cooking. “It’s a tougher ask to introduce soil management systems, to ask growers to make changes to their agricultural practices if it threatens their food security. They’re not going to leave the non-edible residues on the land if it can be used for fuel or animal feed for example,” Professor Schipper says. “But what we’re proposing for developing countries is feasible when other social and economic constraints are considered because it doesn’t require large technological breakthroughs and it doesn’t stop agricultural or horticultural production.”
The research is funded by the New Zealand Government to support the objectives of the Livestock Research Group of the Global Research Alliance on Agricultural Greenhouse Gases.