Carbon Sequestration and Greenhouse Gas Mitigation in Agriculture: Living Up to Potential?

Agriculture is central to the issue of climate change (CC), both in terms of how CC will impact agriculture and food security and how agriculture can help mitigate greenhouse gases (GHG). The IPCC fourth assessment found that the Agricultural sector has the second highest potential for near-term GHG mitigation of the seven major sectors evaluated, amounting to 4.4 billion tonnes CO₂ per yr.  Despite this high mitigation potential, agriculture has largely been on the sidelines with respect to GHG mitigation activities, both in existing international policies as well as in the growing voluntary carbon (C) markets.

Improved management practices that increase C inputs to soil and reduce tillage intensity can increase cropland soil C stocks, removing CO₂ from the atmosphere.  Similarly, pastures and rangeland can be a sink for CO₂ with adoption of improved management. Biochar, a highly stable form of organic C, is receiving interest for soil C sequestration and to improve soil fertility and plant production. Finally, reducing soil N₂O emissions, through improved N management offers significant GHG mitigation potential

While many technologies are proven to sequester soil C and reduce GHGs, inclusion of agriculture as a major mitigation player has been slow.  Economic, social/institutional and policy barriers have all contributed to the hold up.   Arguably, the main barriers to greater engagement of the agricultural sector in GHG mitigation are science and policy related – namely whether we can quantify mitigation with sufficient accuracy and monitor activities to ensure that GHG reductions are maintained.  Soil emissions are widely distributed across the landscape, with high spatial and temporal variability, and thus are difficult to measure.  Further, because of the many interacting factors that impact soil responses to management and the spatial variability of climate and soils, simple emission factor approaches are of limited value.

However, there is a growing movement towards the application of dynamic models, together with coordinated soil measurement networks, to provide effective quantification. Models and supporting, databases, can be embedded within decision support systems for use by non-specialists over the internet. A critical element in such a system is reliable, site-specific information about the management practices being carried out. Here the power of the internet and related technology can directly engage farmers as data suppliers and users.  The potential for a new farmer-industry-government-public partnership, that connects individuals within a new ‘resource information network’, provides a way forward to engage agriculture in GHG mitigation efforts and achieve a more environmentally sustainable agriculture.