Abstract
Total organic carbon (TOC) contents in agricultural soil are presently receiving increased attention, not only because of their relationship to soil fertility, but also due to the sequestration of organic carbon in soil to reduce carbon dioxide emissions. In this research, the spatial patterns of TOC and its relationship with pH at the European scale were studied using hot spot analysis based on the agricultural soil results of the Geochemical Mapping of Agricultural Soil (GEMAS) project. The hot and cold spot maps revealed the overall spatial patterns showing a negative correlation between TOC contents and pH values in European agricultural soil. High TOC contents accompanying low pH values in the north-eastern part of Europe (e.g., Fennoscandia), and low TOC with high pH values in the southern part (e.g., Spain, Italy, Balkan countries). A special feature of co-existence of comparatively low TOC contents and low pH values in north-central Europe was also identified on hot and cold spot analysis maps. It has been found that these patterns are strongly related to the high concentration of SiO2 (quartz) in the coarse-textured glacial sediments in north-central Europe. The hot spot analysis was effective, therefore, in highlighting the spatial patterns of TOC in European agricultural soil and helpful to identify hidden patterns.
A special co-existence of both low soil total organic carbon contents and low pH values was identified in agricultural soil in north-central Europe, which is highly correlated with the high concentration of SiO2 in those soil. [Display omitted]
•Hot spot analysis reveals spatial patterns of TOC in European agricultural soil.•Soil TOC and pH values are negatively correlated at European scale.•Low TOC and low pH values are related to coarse-textured glacial sediments.•Co-existence of low TOC and low pH values occur in north-central Europe.