Restoring soil quality of woody agroecosystems in Mediterranean drylands through regenerative agriculture

Abstract Regenerative agriculture (RA) is gaining increasing recognition as a plausible solution to restore degraded agroecosystems. In Mediterranean drylands, RA is at incipient state of development and has been limitedly adopted by farmers, partly due to the lack of empirical evidence on its impacts. To support its large-scale adoption, we carried out a participatory monitoring project in southeast Spain, involving local farmers applying different RA practices in 9 almond farms. To assess the effect of RA, in each farm we selected one field with regenerative management and one nearby field with conventional management based on frequent tillage (CT). We clustered fields under regenerative management based on the RA practices applied by farmers and distinguished 4 types of RA treatments: 1) reduced tillage with green manure (GM), 2) reduced tillage with organic amendments (OA), 3) reduced tillage with green manure and organic amendments (GM&OA), and 4) no tillage with permanent natural covers and organic amendments (NT&OA). We evaluated the impacts of RA compared to CT by comparing physical (bulk density and aggregate stability), chemical (pH, salinity, total N, P, K, available P, and exchangeable cations) and biological (SOC, POC, PON, microbial activity) properties of soil quality and the nutritional status of almond trees (leaf N, P and K). Our results show that GM improved soil physical properties, presenting higher soil aggregate stability. We found that OA improved most soil chemical and biological properties, showing higher contents of SOC, POC, PON, total N, K, P, available P, exchangeable cations and microbial respiration. RA treatments combining ground covers and organic amendments (GM&OA and NT&OA) exhibited greater overall soil quality restoration than individual practices. NT&OA stood out for presenting the highest soil quality improvements. All RA treatments maintained similar crop nutritional status compared to CT. We conclude that RA has strong potential to restore the physical, chemical and biological quality of soils of woody agroecosystems in Mediterranean drylands without compromising their nutritional status, thereby enhancing their resilience to climate change and long term sustainability.