Fundamental Research Division
The DRF at the CEA assemble approximately 6,000 scientists since January 2016.
Découvertes et avancées | Scientific result | Climate | Agronomy | Climatic models
According to a Peking University study involving the LSCE (CEA-CNRS-UVSQ), there are "hot spots" of soil-based emissions of nitrous oxide (N2O), a very powerful greenhouse gas. Just by focusing on those soils that receive excessive nitrogen fertilizer deposits, it should be possible to reduce total nitrous oxide emissions from soils by nearly 20%.
Agricultural soils are the largest source of anthropogenic emissions of nitrous oxide (N2O), whose greenhouse effect is 300 times more powerful than that of carbon dioxide. The contribution of atmospheric N2O to the greenhouse effect is 6%.
If nitrogen fertilizer use was limited everywhere to just the correct dose without any loss of agricultural production, these emissions could be reduced by 30%, equivalent to current emission levels from cultivated lands in China and the USA! The potential for mitigating climate change by reducing N2O emissions from cropland is therefore large.
For the first time, researchers conducted a regional-scale analysis. Looking at 234 sites around the world, they comprehensively compiled data on N2O emissions relative to nitrogen fertilizer deposition, referred to as an "emission factor". Then, they used a machine learning model to extrapolate these emission factors to the entire planet, taking into account crop types, local climates, soil properties, and land management practices.
The researchers were surprised to find large geographical disparities in N2O emission factors, with differences of up to a factor of one hundred. Contrary to their expectations, these differences are not primarily driven by fertilizer deposition and agricultural practices: climate and soil type also play key roles in the occurrence of large-scale hot spots.
"We show that two-thirds of the climate change mitigation potential of N2O could be achieved by reducing fertilizer use on only 20% of the world's cropland, especially in humid subtropical agricultural regions," says Philippe Ciais, a researcher at the LSCE. "We need to focus our efforts on areas with high emission factors and reduce excessive fertilizer applications in these areas."
Global mapping of crop-specific emission factors highlights hotspots of nitrous oxide mitigation, Nature Food
CEA is a French government-funded technological research organisation in four main areas: low-carbon energies, defense and security, information technologies and health technologies. A prominent player in the European Research Area, it is involved in setting up collaborative projects with many partners around the world.