Biogenic volatile organic compounds (BVOCs) play a large role in atmospheric chemistry as they are precursors of ozone and secondary organic aerosols. However, the analysis of their emission in croplands is scarce. This work constitutes, to our knowledge, the first quantification of ecosystem-scale biogenic volatile organic compounds (BVOC) fluxes exchanged over a rapeseed crop field. The experimental campaign took place at the FR-Gri ICOS site (near Paris, France) between spring and summer 2017, during which the BVOC fluxes were measured continuously by the eddy-covariance method with a proton-transfer quad-injection time-of-flight mass-spectrometer instrument (PTR-Qi-TOF-MS). Standard emission factors (SEF) and OH reactivity fluxes were computed from the measured fluxes, and compared to the widely used model MEGAN2.1. Fifty-three BVOCs were significantly emitted or deposited during the campaign. Methanol was by far the most emitted one (83 to 91 % of summed emissions), followed by ethanol (1.5 to 11 %) and monoterpenes (1.2 to 1.6 %). Methanol SEF appeared to be overestimated during vegetation stages in MEGAN2.1. In addition, a 4-fold increase of emissions during the late senescence stage confirmed the necessity to use the ageing factor to represent methanol emissions in MEGAN2.1. Most noticeably, monoterpenes SEF computed in this study were 3 to 90 times larger than with MEGAN2.1. Consequently, this study shows that the share of OH reactivity represented by terpenoid compounds was underestimated in previous studies, pointing out the potentially more significant contribution of croplands to secondary organic aerosol formation.