The REGEN-SN project is a field experiment in Sierra Nevada testing a regenerative agriculture model that combines livestock and crops to restore degraded soils. Conducted on a one-hectare site, it evaluates a circular fertility system using local pajuna cattle manure and managed grazing instead of commercial inputs. The experiment investigates how the origin and ecological context of organic inputs affect soil regeneration, resilience, and biological activity. Three practices—ecological manure, rotational grazing, and winter cover crops—are tested to establish a fruit orchard under perennial conditions. Soil health is monitored through physical, chemical, and biological indicators, producing scalable, low-cost solutions for Mediterranean mountain farming.