Effects of soil-protecting agricultural practices on soil organic carbon and productivity in fruit tree orchards

This 4-year on-farm study reports the effects of different agricultural practices on yield and soil organic carbon (SOC) in kiwifruit and apricot orchards grown in a Mediterranean area. Groups of plants under local orchard management (LOM,x) practices (i.e. soil tillage, removing of pruning residues and mineral fertilisers) were compared with plots under soil-protecting orchard management (SPOM) actions (i.e. cover crop, no-tillage, compost application and mulching of pruning residues). In the SPOM blocks fertilisation rate was based on plant demand and irrigation volumes calculated on the evapotranspiration values, while they were empirically calculated in the LOM plots. Results show that yield was 28–50 per cent enhanced by SPOM practices while SOC remained close to the initial values. In comparison with LOM plots, changed practices increased up to 28–90 per cent the amount of P and K, and 13 per cent that of N annually incorporated into soil increasing their reservoir in the soil. The study demonstrates that appropriate land management can increase the mean annual carbon soil inputs from about 15 to 90 t ha1 per year.