Phosphorus and potassium cycling, recycling, and losses in Mediterranean olive orchards: Impact of management and erosion on nutrient balances

This study assessed annual phosphorus (P) and potassium (K) balances in twelve traditional olive orchards in Andalusia, Spain, ranging from conventional (types A and B) to nature-based systems (types C and D). Inputs, outputs, internal flows, and ecological indicators such as the cycling index (CI) and nutrient input/output footprints per liter of olive oil were quantified. Nature-based systems recycled more nutrients, with average efficiencies of 72% for P and 59% for K, compared to 57% and 47% in conventional orchards. A regression model based on fruit yield and canopy area explained 69% of annual P demand and 76% of K demand. Without considering erosion, annual balances were neutral or slightly positive, up to + 4.22 kg P ha⁻¹ y⁻¹ and + 12.57 kg K ha⁻¹ y⁻¹ , with no significant differences between systems due to high within-group variability. Including erosion drastically altered K balances, from + 16.17 to –377.15 kg K ha⁻¹ y⁻¹ on average, reflecting high soil K content, while P remained relatively stable due to its lower abundance and geochemical immobilization. Overall, nature-based management enhances nutrient efficiency but cannot prevent severe losses under erosion, highlighting the need to combine agroecological practices with soil conservation to sustain fertility and long-term productivity.