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Context and challenges

Grazing-based dairy farms are particularly sensitive to extreme weather, which are expected to be more frequent and more extreme (IPCC, 2021), especially when they occur at key periods for grass growth or crop establishment/maturity. Recurring extreme weather events compromise the resilience of these systems. One of the remedies of these systems is to resort to stocks of conserved fodder, or, failing that, to purchase fodder when it is impossible to graze. However, these stocks have a shelf life of only two years and surpluses can be a problem, except for dual-purpose crops. On the other hand, the average increase in temperatures and atmospheric CO2 concentration offers opportunities for grass growth in the autumn and winter seasons, provided the soil is of sufficiently good quality. Furthermore, to meet the objectives of the national low-carbon strategy, it is crucial to maintain the areas already under grass and/or to extend the duration of temporary grasslands, and therefore to maintain grazing-based dairy systems.

This project seeks to evaluate medium-term changes in lowland grassland dairy farming systems in response to climate change, taking into account the uncertainties associated with modelling climate and forage resources. It also aims to analyse the consequences of these changes on the production and carbon footprint of these farms, as well as to identify possible breakpoints between the resilience of these systems and their contribution to the mitigation of greenhouse gas (GHG) emissions.

The originality of the project lies in the modelling of the joint evolution, in a context of climate change, of the 'herd' and 'forage resource' components of dairy farms, which has not been widely addressed until now. Another originality lies in the fact that it aims to study the possible incompatibilities between the adaptation of these systems and their contribution to the goal of climate change mitigation. The project relies on complementary disciplines and expertise/research, particularly on ways to adapt these systems and mitigate the contribution of agriculture and livestock to climate change.

Goals

This project aims to answer the following questions, in this order of priority:

• What intra-/inter-annual changes in climate (average, extreme weather events) and forage resources (distribution, accessibility) can be expected at the scale of the study area? Do patterns of similar extreme weather events emerge from year to year?
• What adaptations to forage systems can be anticipated in response to changes in forage resources?
• What are the consequences for milk production, carbon storage and GHG emissions on the farm?
• What are the consequences for the resilience and carbon footprint of the lowland systems studied? Are there break points or synergies between the two? What changes in the climate cause them?
• How does the uncertainty/variability linked to the modelling of the future climate and pedoclimate of the territory affect the evaluation of the variables of interest at the herd and forage system level?

INRAE units involved

• PEGASE, Rennes
• MIAT, Toulouse
• MoSAR, Grignon
• Agroclim, Avignon
• BioEcoAgro, Laon

External partners : IDELE