Carbon sequestration offsets a large share of GHG emissions in dehesa cattle production

Abstract

The contribution of cattle production to climate change is increasingly recognized, and there is a need to identify those systems minimizing emissions and maximizing carbon (C) sinks. In the Southwest of the Iberian Peninsula, cattle are produced on dehesa agroforestry systems, where cows and calves graze together until weaning, and calf fattening is based on external feed. The aim of this study was to assess the Carbon footprint (CF) of beef of this extensive production system using Life Cycle Assessment (LCA) methodology. The study collects data from 15 extensive cattle farms, 6 organically (ORG) and 9 conventionally (CONV) managed; 4 farms had their own fattening facilities while most of the farms sold calves to 2 specialised fattening farms also studied. CF calculation includes field monitoring of C sequestration on soils and woody biomass in a selection of well-known points with previous estimations. The limit of the system was “cradle to gate”, and the functional unit was 1 kg LW of calf at slaughtering age. The main C sinks of the dehesa system sequestered an average of 3.3 t CO2eq ha−1 year−1. The average CF of the final product was 6.43 ± 21.46 kg CO2eq kgLW−1, with numerically lower but not statistically different average CF in ORG than in CONV systems. The inclusion of C sequestration, that averaged −13.52 kg CO2eq kgLW−1, offset 95% and 54% on ORG and CONV farms, respectively. In some cases, C sequestration compensated all GHG emissions and resulted in negative CF. There was a direct negative relationship between CF and stocking rate, leading to negative CF values in those farms with lowest stocking rates.