Download 4 per 1000 Carbon sequestration in soils for food security and the

4 per 1000
Carbon sequestration in soils
SOILS FOR FOOD SECURITY AND THE CLIMATE
In a context of climate change, feeding 9.5 billion people in 2050
will depend on our ability to keep soils alive and in good health.
THE THREAT: THE GREENHOUSE EFFECT
Human activities (industry, transport, agriculture) emit enormous quantities of carbon dioxide (CO2) into the atmosphere, which reinforces the greenhouse effect and accelerates climate change.
40%
SOIL DEGRADATION
THREATENS NEARLY HALF
OF THE EARTH’S LAND MASS
THE CONTEXT: SOIL DEGRADATION
Thanks to plants and living organisms, soils contain two to three times more carbon
than the atmosphere. Carbon-rich soil organic matter is essential: it retains the water, nitrogen and phosphorus that are indispensable to agriculture.
But alternating phases of drought and intense rainfall accentuate erosive phenomena. In the long term, almost 30 million hectares of arable land could be lost every
ten years.
THE SOLUTION: CARBON STORAGE
If the carbon stocks in the top 40 centimetres of soil could be increased by 4 per 1000 each year, this could theoretically help to stop the current rise in the quantity of CO2 in the atmosphere, on condition that deforestation is halted.
THE METHODS: SOIL MANAGEMENT AND AGROECOLOGY
Farming and forestry practices that favour carbon storage in soils and biomass (permanent soil cover, use of organic
products, diversified cropping systems, agroforestry, etc.) will contribute to preserving natural resources and biodiversity, increasing yields and stabilising them in the context of severe climatic events.
THE GOAL: GLOBAL FOOD SECURITY
An increase in soil carbon levels would therefore contribute not only to stabilising the climate but also to ensuring
food security and adaptation to climate change.
The impact of the ‘4/1000’ (0.4% per year) target of
biological soil carbon sequestration on the global carbon cycle.
Annual carbon fluxes and carbon stocks are expressed in GtC (billions metric
tons of carbon) before (A) and after (B) full implementation of a 0.4% annual soil carbon
sequestration and of halting net emissions from land use change.
Figure B shows the budget of anthropogenic CO2 as if all land-based sequestration could be implemented within one year.
Modified after the Global Carbon Atlas, 2014
The “4 per 1000” initiative proposes to increase
organic matter contents and encourage carbon
sequestration in soils, through the application
of appropriate farming and forestry practices.
4 PER 1000, HOW CAN THIS BE ACHIEVED?
Farming systems throughout the world must therefore evolve and practical
solutions are available. The benefits of these new practices on food security
and climate concern us all.
570 million farms worldwide, and more than
3 billion people living in rural areas,
could implement these practices.
”
5
PRACTICES
TO BE DEVELOPED
Examples can be seen in Europe. The Portuguese Carbon Fund has thus calculated that since
2009, the carbon storage achieved by restoring degraded grasslands has reached 1 million
tonnes, the actions implemented including the sowing of grass-legume mixtures and
the application of phosphorus to restore the soil. And this is what they did: they resowed
appropriate forage plants, supplied sufficient fertilisation and obtained strong vegetative
growth which produced large quantities of soil organic matter and hence increased carbon
storage.”
Jean-François Soussana, Inra
• Avoid leaving the soil bare in order to limit carbon losses
• Restore degraded crops, grasslands and forests
• Plant trees and legumes which fix atmospheric nitrogen in the soil
• Feed the soil with manure and composts
• Conserve and collect water at the feet of plants to favour plant growth
Applied to the surface horizon of the world’s soils, or a stock of around 860 billion tonnes of carbon, the 4‰ target
would result in the annual storage of 3.4 billion tonnes of soil carbon, thus counterbalancing the rise in atmospheric
CO2. This measure would be extended beyond agricultural soils to most soils and their uses, including forests.
THE COST
FOR CROPS, 20 to 40 USD per tonne of CO2
FOR GRASSLANDS AND FORESTS, 50 or 80 USD per tonne of CO2
Carbon would continue to accumulate in soils for
twenty to thirty years after the introduction of good
practices, if they are sustained.
Conception et réalisation : Studio graphique - Inra-UCPC / Photo : © Fotolia
Quantifying carbon stocks in soils, adapting agricultural
practices to each country, finding measures to incite
farmers to adopt them... farmers, economic players,
associations, regional and local authorities and countries
are supporting researchers around the 4 per 1000 initiative
for food security and climate.
This initiative is part of the Lima-Paris Action Agenda.