Biochar and biofertilisation are seen as agents for improving plant carbon budget, decreasing greenhouse gas emissions and improving C sequestration while poplar is considered as an alternative for fossil fuel. Unrooted stalks of poplar were submitted to different fertilisation (two biofertilizers and mineral fertilizers) and biochar treatments. CO₂ emissions from soils were measured with flux chambers during the first two growing seasons. Plant respiration was also measured during the second year. The presentation will discuss correlations between CO₂ emissions from soils and plants and treatments affecting soil properties.