Cropping systems and agricultural sustainability: the role of long-term field experiments in the Mediterranean region

This thesis examines the role of Long-Term Field Experiments (LTEs) in characterising the agronomic sustainability of Mediterranean rainfed cereal-based cropping systems. It combines a national database of Italian LTEs—developed to harmonise information on the experiments and their associated publications, and to assess their comparability and thematic coverage—with a multi-year analysis of differences between conventional and organic management in durum wheat and weed responses along agrometeorological and edaphic drivers. The multi-year analysis was conducted in the MASCOT (Mediterranean Arable Systems Comparison Trial) case study, located at the ‘Enrico Avanzi’ Centre for Agro-Environmental Research of the University of Pisa, using data collected from 2002 to 2016. The database systematised information on 27 LTEs, distributed across 10 regions, and 111 associated publications, revealing a marked concentration in northern Italy and thematic coverage predominantly focused on soil chemical quality and productivity, with soil biological and physical quality and greenhouse gas emissions being less represented. Within MASCOT, the associations linking growing degree days and cumulative rainfall to durum wheat and weed responses were strongly phase-specific and differed between management systems; crop-cycle length also highlighted trade-offs among grain yield, grain nitrogen content and weed biomass. Soil chemical properties primarily exhibited temporal trajectories within experimental units, with declining pH and increases in total nitrogen and soil organic matter, with the increases in the latter two being more pronounced under organic management, but without corresponding persistent differences in mean levels between systems. Along edaphic gradients, pH represented the main constraint on crop performance and clay the principal buffering factor, whereas total nitrogen and soil organic matter primarily expressed potential fertility rather than effective resource availability.