A study published today in Scientific Reports and conducted by an international group of scientists from the Chinese Academy of Science, The Nature Conservancy and International Center for Tropical Agriculture (CIAT) has revealed how crop farming can make a significant contribution to tackling the threat of climate change, important ramifications for the UN COP23 climate talks currently underway in Germany.
Scientists have previously established that crop production depletes soil carbon through intensive tillage and the excessive use of chemical fertilizers, with an estimated 50-70% loss of soil carbon stocks in cropland soils worldwide (Lal, 2004). Since croplands can sequester more carbon dioxide from the atmosphere if farmers use improved farming practices like increased manure, cover cropping, mulching, conservation tillage, fertility management, and other natural climate solutions such as agroforestry, the international group sought to establish where in the world these activities could deliver the greatest carbon sequestration benefit. The results will be presented tomorrow Wednesday 15 November at the UN climate talks.
Using a small increase in soil carbon, that experts say should be attainable in cropped soils almost everywhere, the scientists found that improved soil management in crop farming could contribute to annual carbon emissions reductions of between 0.9 and 1.85 billion tonnes per year, equivalent to the emissions of Canada and the Philippines combined, or removing between 215 and 400 million cars from the roads.
Justin Adams, TNC, said, “Natural climate solutions are essential to address climate change and investing in our soils is a strategy with massive untapped potential—potential we can realize if we start thinking holistically about the kind of interventions and policies needed from top down and ground up. If we’re to deliver on increasing demand for food, sustaining global health, maintaining biodiversity and tackling climate change, then soil is our most underappreciated ally.”
The study found that most of the world’s soil carbon is stored at northern latitudes, with North America, Northern Europe and Russia accounting for more than half of the world’s soil organic carbon stocks on croplands. In contrast, large areas of croplands in India, across the Sahel, northern China, and Australia have cropland soils that are low in carbon.
Although the capacity to increase soil carbon depends to a large degree on the types of soils and the environment, all of the major agricultural countries in the world were shown to have significant carbon sequestration potential. Whereas the United States has the largest area of croplands and consequently the largest sequestration potential, other major agricultural countries with large areas of cropland such as India, China, and Russia can make substantial contributions to mitigating climate change through soil carbon sequestration.
Table 1. Top 10 Countries for Carbon Sequestration Potential from Crop Farming, compared to cars removed from the road (high scenario)
|Country||Soil Carbon Sequestration Capacity (MtC/year)||Equivalent to removing # of Cars (millions)|
The scientists also noted in the paper that there are other important benefits of soil management, including increased yields from improved soil fertility and better water holding capacity, which also support farmers with adapting to climate change.
The study in Scientific Reports is available here: www.nature.com/articles/s41598-017-15794-8
For data and maps on soil carbon from the study, please visit: http://ciat.cgiar.org/global-soil-carbon
For information from TNC on natural climate solutions, please visit: https://global.nature.org/collections/soil-solutions