GC108-08
Effects of a public policy that aims to reduce large-scale nitrogen fertilizer usage over European agriculture: ecosystem carbon and biodiversity changes

Tuesday, 15 December 2020: 11:58
Virtual
Narayanappa Devaraju1, Rémi Prudhomme2, Anna Lungarska3, Nathalie De Noblet-Decoudre4, Raja Chakir3, Thierry Brunelle2 and Pierre-Alain Jayet5, (1)IPSL/LSCE (Laboratoire des Sciences du Climat et de l'Environnement), CEA-CNRS-UVSQ UMR, L'Orme des Merisiers, Gif sur Yvette Cedex, France, (2)Cirad, UMR CIRED, 94736 Nogent-sur-Marne, France, (3)Économie Publique, INRA, AgroParisTech, Université Paris-Saclay,, Thiverval-Grignon, France, (4)Institut Pierre Simon Laplace, Paris, France, (5)INRA AgroParisTech, Université Paris-Saclay, Thiverval-Grignon, France
Abstract:
In this study, we investigate the impacts of a policy scenario that aims to halve nitrogen (N)
fertilizer application over European agriculture on the carbon cycle and biodiversity changes.
By integrating multi-scale land-use models: econometric, economic (AROPAj and NLU), agro-
land surface (ORCHIDEE-CROP) and a biodiversity model (PREDICTS), we quantify the
changes in some ecosystem services due to policy decision. The coupling of two economic
models (AROPAj and NLU) with the ORCHIDEE-CROP and PREDICTS details how land-use
changes induced by the N halving policy influence net primary productivity (NPP), ecosystem
carbon, species richness and the composition changes of the ecological community in
agricultural land. We find that the policy impact on the soil carbon and biodiversity changes
depends on the land-use change, which can be either an increase in grazing land as a result of an
agricultural takeover or an increase in cultivated land to compensate the loss of crop yield.
Therefore, depending on land-use changes, the simulated carbon cycle vary from CO2 emissions
to the atmosphere with a reduction in NPP and soil carbon to the carbon sequestration in the land with an
increase in NPP and soil carbon. Biodiversity is also impacted with a change in the composition of ecological communities and species richness.