Integrated weed management (IWM) in cropping systems aims to lower the reliance on herbicides of the crops, by introducing new combinations of agricultural practices in the system development (Munier-Jolain et al, 2009). These combinations may greatly change from a system to another and include a large variety of practices, such as false seed beds, late sowing, mechanical weeding, reduced tillage, specific crop rotations that alternate spring and winter crops, the choice of crop varieties and the use of pesticides with low ecotoxic impacts. Several implemented agricultural practices are likely to alter soil biogeochemical cycles and different components of the greenhouse gas budget (balance between the carbon sequestration and the greenhouse gas emission) of the system: e.g. crop rotation, dates and level of nitrogen fertilization and tillage. The main objectives of our study were to evaluate i) the N2O fluxes emitted from soil during one year for 4 cropping systems (i.e. 3 IWM systems and a local reference of conventional system), and ii) to investigate the relationship between the measured fluxes and soil parameters and the agricultural practices of each system.