The Use of Pruning Residue Mulch and Spontaneous Groundcovers to Control Erosion and Carbon Loss in Olive Orchards

Many olive orchards are rainfed and located on poor and sloping soil. Tillage is the most common soil management system, leaving the soil vulnerable to erosion. Pruning is a frequently used field operation in olive orchards that generates biomass; thus, pruning residue can be shredded and used as mulch to cover and nourish the soil. Several strategies using pruning residue mulch and spontaneous groundcovers were established to study their effect on controlling runoff, erosion and soil organic carbon (SOC) loss under simulated rainfall. The simulation trials were conducted under two different intensity rainfalls: high-intensity rainfall and medium-intensity rainfall, which averaged 36.8 and 16.4 mm/h, respectively. A tillage system was compared to spontaneous vegetation using two doses of pruning residue mulch, 10 and 30 t/ha, and a mixture of 10 t/ha of pruning residue applied on spontaneous vegetation. Runoff was reduced to a higher degree with spontaneous groundcovers as infiltration was favoured. Soil loss was reduced by more than 95% and SOC loss by more than 85% regarding tillage with any type of groundcover for both rainfall intensities. Spontaneous vegetation with a pruning residue mulch system kept the soil protected to a greater degree against erosive processes, making the system more sustainable.