Field-based assessment of carbon farming practices in Mediterranean olive groves: Emission reductions and sequestration outcomes

Olive farming systems are increasingly recognized for their potential role in climate change mitigation through carbon sequestration. This study evaluates the carbon footprint and sequestration capacity of 16 commercial olive farms of Andalusia, Spain, spanning a gradient of annual manageable soil organic carbon (MSOC) inputs, including compost, manure, pruning residues, and spontaneous cover crops. CO 2 equivalent (CO 2 -eq) emissions from agricultural operations were quantified through life cycle assessment methodology with both area- and yield-based functional units. Annual soil organic carbon change was estimated with the RothC model using site-specific climate, soil, and management data, while carbon accumulation in permanent tree biomass was measured through tree biovolume analysis of representative trees. CO 2 eq emissions and annual organic carbon accumulation in soil and perennial tree biomass were compared then to assess net carbon balance. Farms with high MSOC inputs showed significantly lower CO 2 -eq (0.8 Mg CO 2 -eq ha −1 y −1 ) than medium- (2.0 Mg CO 2 -eq ha −1 y −1 ) and low-inputs (1.3 Mg CO 2 -eq ha −1 y −1 ), primarily due to reduced fertilization-related emissions. Yield-based emissions also declined by up to 50 % in high MSOC systems. Net CO 2 footprints averaged −0.14, −0.43, and −3.15 Mg CO 2 ha −1 y −1 for low, medium, and high MSOC farms, respectively. A strong correlation (R 2 = 0.97) between emissions and management indicators (diesel use, nitrogen application, and irrigation volume) supports their relevance for climate-smart farming decisions. These findings demonstrate that increased organic carbon inputs can transform olive groves from carbon-neutral or emitting systems into net carbon sinks, offering practical guidance for MSOC-based carbon farming strategies. • Higher organic matter inputs reduce CO 2 -eq and enhance carbon sequestration. • High organic input farms boost SOC up to 4 Mg CO 2 -eq ha −1 y −1 . • Organic fertilization and cover cropping drive emission reductions. • Fertilizer type strongly affects CO 2 -eq emission. • Simple farm-level indicators correlate farm CO 2 emissions (R 2 = 0.95).