The impact of environmental policy on soil quality: Organic carbon and phosphorus levels in croplands and grasslands of the European Natura 2000 network

In this study, the Natura 2000 nature protection network of the European Union is assessed in the context of soil quality management. We explore the hypothesis that the soil quality of croplands and grasslands — as indicated by soil organic carbon and phosphorus levels — is better in terms of environmental parameters within the Natura 2000 network than outside it. The soil organic carbon and phosphorus content of 479 cropland and 450 grassland sites within Natura 2000 were compared with their nearest neighbours outside the network. The comparisons were repeated for pairs of both cropland and grassland sites by soil texture groups. The study revealed that organic carbon content was significantly higher in Natura 2000 sites than in non-protected areas for both croplands and grasslands. For croplands, this was true only for those with signs of ploughing, whereas for croplands without signs of ploughing there were no significant differences between Natura 2000 and non-protected areas. Areas with sand and loamy sand soils had significantly higher soil organic carbon content within the Natura 2000 network than outside it, for both croplands and grasslands. This was the only texture class that showed a significant difference in the case of croplands, whereas three further texture groups had higher soil organic carbon content in Natura 2000 grassland sites than on grassland sites outside this network. There was no significant difference in soil phosphorus content between areas within the Natura 2000 network and non-protected areas, except for grasslands with light textured soils, where soil phosphorus levels were significantly lower within Natura 2000 sites than outside them. The results suggest that the management of croplands and grasslands of Natura 2000 sites tends to perform better than that of adjacent areas with similar land cover in terms of soil carbon conservation. The difference is more evident for sites with certain soil characteristics. On the other hand, the nutrient input - as determined by phosphorus levels - of Natura 2000 croplands and grasslands generally does not appear to be less intensive than that of surrounding areas outside the network.