Agroforestry and intensive grazing for maximizing carbon sequestration within cattle industry

The cattle industry is a sector that emits significant amount of greenhouse (GHG). More and more livestock companies are thus looking for solutions to reduce their environmental impact (Dollé et al., 2015). In Canada and in Québec, GHG emissions from agriculture account for 8,5 and 9,3 % of total emissions, respectively, and about 40 % of these emissions are produced by ruminants (ECCC 2018; MDDELCC 2018). However, a significant part of these emissions can be offset by carbon storage (C) (Dollé et al. 2015). The proposed project, in partnership with Ferme Lafontaine-Noël, aims at developping innovative agronomic practices to increase C storage in soils and biomass in order to offset the GHG emitted by the exploitation activities. Ruminant livestock industrials are key players in fighting against climate change: they emit GHGs, but their farmland can store significant amount of C if the land is properly managed. The development of agroforestry systems on permanent grasslands is a first example of an innovative management practice that can rapidly increase C storage in soils and biomass (Hamon et al. 2009; Dollé et al. 2015; Paustian et al., 2016). A second
example is the intensification of pasture management, where grazing of the herd occurs in rotation over a given surface area for a short period of time; such management can increase the storage and stability of soil C (Machmuller et al. 2015; Benmohamed et al. 2019). The implementation of
agroforestry systems on intensively managed pastures could be doubly beneficial in terms of C storage. The site selected to implement the experimental plots will first be characterized by sampling soils at two depths (0-20 and 20-40 cm) to determine the initial quantities of C stored in soil and root biomass. Subsequently, experimental plots will be set up. They will consist of two treatments repeated four times. The first treatment is the one currently applied on the farm, which is continuous grazing for 7 days; it represents the business as usual scenario. The second treatment is an agroforestry grazing systems where grazing is carried out in intensive rotation within pastures bordered with hedgerows of planted trees. The hedgerows will be subdivided to evaluate the impact of different tree species planted alone or in mixture. Finally, we will conduct a second sampling of soils and roots on grazed areas and hedgerows at the end of the second growing season to compare the short-term impact of the agroforestry grazing system to the business as usual scenario. This project also represents an opportunity to test the feasibility of implementing an agroforestry system on a commercial scale. This has never been evaluated in Québec. It represents a unique opportunity for the partners to implement a long-term experimental research site devoted to evaluate how agroforestry grazing systems can help reduced GHG emissions and mitigate climate change.