Cover crops promote crop productivity but do not enhance weed management in tillage-based cropping systems

Cover crops (CC) have been proposed as a promising ecological tool to manage weeds and increase crop productivity. We hypothesized that the repeated use of CC could yield directly through nitrogen release and/or indirectly modification weed communities. Data were collected on biomass, community composition, during one complete rotation cycle (CC-sunflower-durum wheat-CC-maize-durum wheat) from 2011 2015, 18 years after beginning long-term, single-site, split-split plot experiment focusing tillage systems (conventional (CT) vs. reduced (RT)), rates species (Brassica juncea (L.) Czern. (Bj), Vicia villosa Roth (Vv), Trifolium squarrosum L. (Ts) winter baresoil control (C)). Univariate response variables analyzed with generalized mixed effect models data multivariate linear models. During fallow period, Bj suppressed biomass (with respect C) by 79, 75, 34, 28 % in CT:2012, RT:2012, CT:2014 RT: 2014, respectively, whereas Vv only 69 37 CT RT 2012, respectively. Greater suppression for than or Ts at lower levels productivity (200 g dry m?²) was attributed importance traits such nitrophily, allelopathy quick soil coverage. The suppressive period greater (?slope = ?0.28) ?0.16), possibly due contrasted flora growth dynamics. Tillage herbicides overrode potential communities subsequent crops. integration highly productive legume CC, Vv, allowed maize 65 absence N fertilisation 23 lowest level. effects sunflower durum wheat limited weather conditions time, These results highlight sustaining while reducing fertilisation. Further studies need identify less intensive management practices can complement rather override them.