Circular agroecology practices for soil health and valorisation of urban and rural wastes

Climate change, lack of water, higher temperatures, and rising energy costs represent major and interconnected threats facing Mediterranean agriculture. Increasing climatic variability, more erratic rainfall, and frequent extreme events are reducing the reliability of rain-fed cropping systems, while the recent energy crisis is making input-intensive practices increasingly difficult to sustain. In this context, the integration of agroecological management with circular economy strategies has been proposed as a means to restore soil ecosystem functions, support crops through the recycling of locally available organic wastes, and improve energy efficiency. This thesis evaluates the potential of this integrated approach through a compendium of complementary studies. First, a 30-year analysis of the Montepaldi Long-Term Experiment reveals that both organic and conventional farming systems experienced a significant yield decline consistent with a worsening water balance; however, organic management maintained substantially higher energy use efficiency despite lower winter cereal yields. Second, a systematic review of Municipal Solid Waste Compost (MSWC) confirms that its application can increase crop yields and soil organic matter content, with the most consistent benefits observed at high application rates, while highlighting strong variability in waste stream composition and composting procedures, as well as the potential introduction of contaminants such as heavy metals and microplastics. Third, a two-year field trial on winter cereals at MoLTE tested a realistic repeated application rate (2 t/ha}, corresponding to the most common regional availability) of composted vine prunings and vermicompost derived from spent coffee grounds, resulting in improved soil aggregate stability and a yield increase in the second year, while emphasizing the need for explicit phosphorus management. Fourth, a mesocosm study assessed behavioral and functional responses of the earthworm Hormogaster samnitica, the most abundant species at MoLTE, demonstrating size-dependent functional roles: larger individuals created wider and deeper macropores with potential implications for water infiltration; composted vine prunings were associated with increased earthworm activity and macroporosity in amended soil layers compared to vermicompost; a two-choice preference test revealed weak and poorly differentiated substrate selection by Hormogaster samnitica, whereas the more generalist species Aporrectodea caliginosa showed a clear preference for compost-based amendments over vermicompost and the control. Finally, a pot experiment investigated dose-dependent responses of substrates and plants to vermicompost and pruning-based composts, showing that vermicompost enhanced both substrate water retention and lettuce growth even at modest application rates, whereas lignin-rich pruning composts produced weaker short-term agronomic responses. Overall, these findings indicate that organic farming, when complemented with context-appropriate amendments derived from the circular economy, can improve energy use efficiency and selected soil functions under Mediterranean constraints. Maximizing these benefits will require aligning amendment type and application rate with local biomass availability, explicitly managing phosphorus inputs, standardizing compost quality, and integrating soil fauna metrics, alongside the development of crop germplasm adapted to water-limited, low-input systems.