Speaker
Description
In the context of climate change, the reduction of greenhouse gases (GHG) emissions and the storage of carbon in soil must be encouraged to limit global warming. The agricultural sector contributes to 18.4 % of French GHG emissions in which 29 % was associated with crop fertilization (Citepa, 2023). Field crops are part of the problem through the use of fertilizers, as well as to the loss of soil carbon through the important export of biomass non compensated by return of organic matter to the soil. However, technical solutions do exist to improve the carbon balance of field crop farming systems such as cover crop, use of organic fertilisers or reduced use of mineral fertilizers (Pellerin et al. 2019).
These technical solutions are mobilized in the innovative systems of the Syppre project in which three French technical institutes on arable crops collaborate (ARVALIS Institut du végétal, Terres Inovia and Institut Technique de la Betterave). This project aims to support the development of innovative arable cropping systems reconciling productivity, economic profitability and environmental protection (Toqué et al. 2015). The innovative systems have been tested since 2017 in five French regions specialised in arable crop production: the deap loamy soils of Picardy, the chalk soils of Champagne, the shallow clay-limestone soils of Berry, the clay-limestone hillsides of Lauragais and the humus-rich soils of Béarn. On each site, an innovative system co-designed with regional agricultural stakeholders has been tested in field conditions, and compared to a reference system, which is representative of current systems observed in the region. To meet Syppre's objectives and local issues, the innovative cropping systems mobilize agroecological solutions using a systemic approach, such as crop diversification, modification of soil tillage, introduction of cover crops, cultivar diversity, and biocontrol products. Cropping systems performances were evaluated every year, and different indicators of soil fertility were measured. The carbon and nitrogen stocks were in particular measured at the beginning of the trial and used to simulate the evolution of soil organic status. The carbon balances of cropping systems were calculated with the French Label Bas Carbone methodology.
After 7 years of trials, we observed a great reduction of nitrogen fertilizer use (between -10% and -46%) and GHG emissions (between 0.33 and 0.7 teqCO2 per year and per hectare) for all the innovative systems compared to the references. Even if all innovative systems do not have a positive effect on carbon storage, all systems have a positive carbon balance. But the economic performances decreased for almost all of them. The presentation will detail the levers used to reduce mineral nitrogen fertilizer amount and improve soil fertility, the effect already visible, and the expected ones in long term scale, the consequences on crop and system performances as well as the effect on carbon balance. It will also discuss the perspectives of interesting solutions to consider in the future, technical or economic.
CITEPA, 2023. Gaz à effet de serre et polluants atmosphériques. Bilan des émissions en France de 1990 à 2022. Rapport Secten éd. 2023.
TOQUE C, CADOUX S, PIERSON, P, DUVAL R, TOUPET A-L, FLENET F, CARROUE B, ANGEVIN F, GATE P. 2015. SYPPRE : A project to promote innovations in arable crop production mobilizing farmers and stakeholders and including co-design, ex-ante evaluation and experimentation of multi-service farming systems matching with regional challenges. 5th International Symposium for Farming Systems Design
PELLERIN et al, 2019. Stocker du carbone dans les sols français, Quel potentiel au regard de l’objectif 4 pour 1000 et à quel coût ? Synthèse du rapport d'étude, INRA (France), 114 p.
| Keywords | Carbon storage, GHG emissions reduction, diversification |
|---|
