Integrated weed management in olive orchard: The effect of spontaneous grass cover crops on weed community, olive production and soil fertility

Olive groves are vital to the Mediterranean Basin's economy, agro-ecology, and culture. Effective weed management is critical for their long-term sustainability and productivity. This study evaluated the effects of spontaneous grass cover crops on weed community structure, olive production, and soil fertility, comparing them with conventional tillage practices. Over three years in southern Spain, two management strategies were tested: a Grass Cover Crop (GCC) system—combining no-tillage with chemical control, pruning wood residues in intra-row spaces, and spontaneous grass cover crops in inter-row spaces and a Tillage (TL) system, which included tillage operations and pruning wood residues in both intra- and inter-row spaces. Weed community and olive crop impacts were assessed by examining richness, abundance, diversity (Shannon index), and equity (Pielou evenness index) at two time points, alongside evaluations of olive yield, quality, and soil fertility. Before herbicide application, the GCC system exhibited greater weed richness, abundance, and diversity in intra-rows and higher richness and diversity in inter-rows compared to TL. Post-herbicide, richness and abundance remained higher in GCC, with increased diversity in inter-rows, and low weed biomass was maintained. While olive yield and quality were unaffected, soil fertility improved under GCC. These results highlight that integrating soil cover methods, such as spontaneous grass cover crops, can balance crop productivity with beneficial weed diversity, fostering a sustainable agricultural system.