Predicting and mitigating the global warming potential of agro-ecosystems

Simon Lehuger (1) , Benoit Gabrielle (1) , Patricia Laville (1) , Matieyiendu Lamboni (2) , Pierre Cellier (1) , Benjamin Loubet (1)

1 EGC - Environnement et Grandes Cultures
2 Unité MIAJ - INRA - Mathématiques et Informatique Appliquées

Nitrous oxide, carbon dioxide and methane are the main biogenic greenhouse gases (GHG) contributing to the global warming potential (GWP) of agro-ecosystems. Evaluating the impact of agriculture on climate thus requires a capacity to predict the net exchanges of these gases in an systemic approach, as related to environmental conditions and crop management. Here, we used experimental data sets from intensively-monitored cropping systems in Western Europe to calibrate and evaluate the ability of the biophysical crop model CERES-EGC to simulate GHG exchanges at the plot-scale. The experiments involved major crop types (maize-what-barley-rapeseed) on loam and rendzina soils. The model was subsequently extrapolated to predict CO2 and N2O fluxes over entire crop rotations. Indirect emissions (IE) arising from the production of agricultural inputs and from use of farm machinery were also added to the final GWP. One experimental site (involving a wheat-maize-barley rotation on a loamy soil) was a net source of GHG with a GWP of 670 kg CO2-C eq ha-1 yr-1, of which half were due to IE and half to direct N2O emissions. The other site (involving a rapeseed-wheat-barley rotation on a rendzina) was a net sink of GHG for -650 kg CO2‑C eq ha-1 yr-1, mainly due to a higher predicted C sequestration potential and C return from crops. Some mitigation options were tested to design productive agro-ecosystems with low global warming impact.

Domaines: Ecologie, Environnement; Ecosystèmes; Bioclimatologie; Agronomie

Simon Lehuger, Benoit Gabrielle, Patricia Laville, Matieyiendu Lamboni, Pierre Cellier, et al.. Predicting and mitigating the global warming potential of agro-ecosystems. 2009. ⟨hal-00414286⟩