Soil carbon 4 per mille

Abstract

International audienceThe ‘4 per mille Soils for Food Security and Climate’ was launched at the COP21 with an aspiration to increase global soil organic matter stocks by 4 per 1000 (or 0.4 %) per year as a compensation for the global emissions of greenhouse gases by anthropogenic sources. This paper surveyed the soil organic carbon (SOC) stock estimates and sequestration potentials from 20 regions in the world (New Zealand, Chile, South Africa, Australia, Tanzania, Indonesia, Kenya, Nigeria, India, China Taiwan, South Korea, China Mainland, United States of America, France, Canada, Belgium, England & Wales, Ireland, Scotland, and Russia). We asked whether the 4 per mille initiative is feasible for the region. The outcomes highlight region specific efforts and scopes for soil carbon sequestration. Reported soil C sequestration rates globally show that under best management practices, 4 per mille or even higher sequestration rates can be accomplished. High C sequestration rates (up to 10 per mille) can be achieved for soils with low initial SOC stock (topsoil less than 30 t C ha⁻¹), and at the first twenty years after implementation of best management practices. In addition, areas which have reached equilibrium will not be able to further increase their sequestration. We found that most studies on SOC sequestration only consider topsoil (up to 0.3 m depth), as it is considered to be most affected by management techniques. The 4 per mille number was based on a blanket calculation of the whole global soil profile C stock, however the potential to increase SOC is mostly on managed agricultural lands. If we consider 4 per mille in the top 1m of global agricultural soils, SOC sequestration is between 2-3 Gt C year⁻¹, which effectively offset 20–35% of global anthropogenic greenhouse gas emissions. As a strategy for climate change mitigation, soil carbon sequestration buys time over the next ten to twenty years while other effective sequestration and low carbon technologies become viable. The challenge for cropping farmers is to find disruptive technologies that will further improve soil condition and deliver increased soil carbon. Progress in 4 per mille requires collaboration and communication between scientists, farmers, policy makers, and marketeers

Ideas and perspectives: Can we use the soil carbon saturation deficit to quantitatively assess the soil carbon storage potential, or should we explore other strategies?

“…For instance, O'Rourke et al (2015) considered that "Translating what is known about SOC at the particle scale into meaningful policy can be achieved through the concept of SOC saturation" and Misnany et al (2017) citing the work by Hassink (1997) suggested that 25 determining soil C saturation deficit would be needed to identify regions with the highest SOC stock increase potential. The potential link between soil C saturation deficit and soil C storage potential is therefore actively discussed.…”

Resource Use Efficiency as a Climate Smart Approach: Case of Smallholder Maize Farmers in Nyando, Kenya

“…These results provide a strong case study for the "4 per mille Soils for Food Security and Climate" initiative that was announced at the UNFCCC (United Nations Framework Convention on Climate Change) Conference of Parties meeting in 2015 [45]. "4 per mille" recognizes the dual importance of soil carbon as a productive asset and as a means for sequestration of carbon from the global atmosphere.…”

Confronting Climate Change Challenges to Dryland Cereal Production: A Call for Collaborative, Transdisciplinary Research, and Producer Engagement

“…International efforts to identify, verify, and encourage farming practices that reduce GHG emissions are making gradual progress in gaining inclusion in many countries' "nationally determined contributions" to reduce emissions (i.e., UNFCCC: COP21 Paris Agreement; Richards et al, 2015). In addition, a related initiative by the French Ministry of Agriculture and civil society NGO's seeks to promote farming practices that sequester organic carbon in soils: www.4p1000.org (Minasny et al, 2017), effectively drawing down atmospheric CO 2 levels while simultaneously improving soil health at landscape scales (FAO, 2017).…”