Soil organic carbon stocks in agricultural soils of Catalonia: a tool for climate change mitigation

Abstract

Determining the soil organic carbon stocks (SOC-S) in agricultural soils, assessing the importance of their variables and understanding their spatial distribution over the territory is crucial to predict possible future scenarios and to design appropriate strategies of climate-change mitigation and adaptation. In this study we characterized and modelled the agricultural SOC-S of Catalonia (NE Spain) in topsoil (0-30 cm) and subsoil (30-100 cm) based on data from 2,186 and 1,612 soil profiles, respectively. We used a set of environmental factors and a statistical approach in order to: i) assess the effect of the main variables on the distribution of SOC-S, ii) estimate SOC-S according to the type of agricultural land use and iii) map topsoil SOC-S in Catalonia. While topsoil SOC-S mainly depend on climate, soil texture and agricultural practices, subsoil SOC-S are mainly dependent on the physical and chemical properties of the soil. According to the resulting map, the mean stock value for the Catalan cropland in the topsoil is 4.88 ± 0.89 kg C · m-2 (1 kg · m-2 = = 10 t · ha-1), with a total of 47.9 Tg C (1 teragram = 1012 grams = 1 million metric tons) for the whole territory. Our findings would be useful for defining C sequestration strategies on the regional scale based on agricultural land use changes and agricultural management practices in a context of climate change.

Keywords: climate change, Mediterranean agriculture, soil organic carbon, carbon sequestration, crop management, geostatistics.