Carbon footprint of dairy goat production systems: A comparison of three contrasting grazing levels in the Sierra de Grazalema Natural Park (Southern Spain)

Abstract

The main objective of this study was to analyze the carbon footprint (CF) of grazing dairy goat systems in a natural park according to their grazing level. A total of 16 representative grazing goat farms in southern Spain were selected and grouped into three farming systems: low productivity grazing farms (LPG), more intensified grazing farms (MIG) and high productivity grazing farms (HPG). Their CF was analyzed, including greenhouse gas emissions and soil C sequestration according to the farms’ grazing level and milk productivity, taking into account different functional units (one kilogram of fat and protein corrected milk (FPCM) and one hectare) and milk correction. Results showed that all variables differed according to the milk correction applied as the values for cow's milk correction were 41% lower than for sheep's milk correction. Total emissions and contributions of soil carbon sequestration differed according to farming system group; LPG farms had higher total emissions than MIG and HPG farms, however total carbon sequestration was lower in the MIG farms than in the LPG and HPG farms. The CF values ranged from 2.36 to 1.76 kg CO2e kg⁻¹ FPCM for sheep's milk correction and from 1.40 to 1.04 kg CO2e kg⁻¹ FPCM for cow's milk correction. No differences were found between farming system groups in either of the two cases but when calculations took hectare of land as a functional unit, the contribution of MIG farms to the CF was 85% higher than LPG and HPG farms. Therefore it is important to take into account the functional unit used to calculate the CF by analyzing this indicator in a broader context, and including carbon sequestration by grazing livestock in the calculation. In order to reduce the CF of this type of system, it is advisable to make appropriate use of the natural resources and to reach an optimum level of milk productivity, high enough for pastoral livestock farming to be viable.