In semiarid Mediterranean agroecosystems, low and erratic annual rainfall together with the widespread use of mouldboard ploughing (conventional tillage, CT), as the main traditional tillage practice, has led to a depletion of soil organic matter (SOM) and with increases in CO 2 emissions from soil to the atmosphere. In this study, we evaluated the viability of conservation tillage: RT, reduced tillage (chisel and cultivator ploughing) and, especially, NT (no-tillage) to reduce short-term (from 0 to 48h after a tillage operation) and mid-term (from 0h to several days since tillage operation) tillage-induced CO 2 emissions. The study was conducted in three long-term tillage experiments located at different sites of the Ebro river valley (NE Spain) across a precipitation gradient. Soils were classified as: Fluventic Xerocrept, Typic Xerofluvent and Xerollic Calciorthid. Soil temperature and water content were also measured in order to determine their influence on tillage-induced CO 2 fluxes. The majority of the CO 2 flux measured immediately after tillage ranged from 0.17 to 6g CO 2 m −2 h −1 and was from 3 to 15 times greater than the flux before tillage operations, except in NT where soil CO 2 flux was low and steady during the whole study period. Mid-term CO 2 emission showed a different trend depending on the time of the year in which tillage was implemented. Microclimatic soil conditions (soil temperature and water content) had little impact on soil CO 2 emission following tillage. In the semiarid Mediterranean agroecosystems studied, NT had low short-term soil CO 2 efflux compared with other soil tillage systems (e.g., conventional and reduced tillage) and therefore can be recommended to better manage C in soil.