Étude du potentiel du biochar comme moyen de réduction des émissions de gaz à effet de serre (GES) en production laitière

In 2017, the Quebec dairy industry showed revenues of more than $ 2.58 billion for its 3.3 billion liters of milk produced, accounting for a total of 83,000 jobs[1]. These data demonstrate the power of this sector for Quebec. However, agriculture is still responsible for nearly 8% of Quebec GHG emissions, or about 6.5 Mt eq. CO2 per year. The methane (CH4) comes mainly from enteric fermentation from ruminants (32% of global agricultural emissions) and manure storage (7% of global agricultural emissions), while N2O comes from nitrification and denitrification processes of agricultural soils (38% of global agricultural emissions)[2-6]. To help the dairy industry do its part in GHG reduction efforts, new solutions are worth exploring. Since the publication of the FAO report in 2006[7], which considered livestock to be responsible for 18% of anthropogenic GHG emissions, the world of research and industry has sought solutions to overcome this scenario. Currently, food additives that reduce CH4 emissions can be found commercially (ex: plant extract, organic acids, lipids, antibiotics)[8,9]. However, the production of these additives generates GHG. In addition, the high price of these additives limits their use in most farms. Biochar is a co-product obtained through the pyrolysis (CO2-free process) of residual plant biomass (ex: agricultural and forestry)[10], thus contributing to the reduction of GHG emissions. Indeed, this process has a high carbon sequestration potential, because one ton of biochar corresponds to 2.7 tons of eq. CO2[11]. Biochar would reduce enteric CH4 emissions from ruminants when added to their diet[12,13]. It would be beneficial for animal health[14], which would allow a reduction of drugs in breeding. As diet influences the composition of excreta, a biochar effect on GHG production during storage and manure application would also need to be verified[6,15]. A study has shown that biochar can improve nitrogen absorption (N) in goats[16], which would reduce the excretion of N through urine in 66% and thereafter reduce emissions of ammonia and nitrous oxide (N2O). For all these reasons, a consortium made up of partners in applied and academic research, associated with the dairy industry, proposes to carry out a project on biochar and GHG emissions from dairy production in Quebec. The objective of the project is to study the effects of biochar on reduction of CH4 and N2O emissions in dairy production, through the feeding of cows, their excreta and agricultural soils.