Soil Degradation

Abstract

The extent and degree of the main soil degradation processes that have been well identified and assessed in Slovenia are presented within this chapter: soil sealing, soil contamination, soil organic matter (SOM) content and decline, erosion, and soil compaction in forests. Soil sealing, the most important form of degradation, was especially intensive between 2002 and 2007. Intensive housing, construction of infrastructure, and the expansion of new commercial areas in the suburbs of cities raised concern among soil experts already at that time. The total increase in the urbanized surface area in this period was 19,790 ha, or a 22.5% increase over the initial urban surface area. Primarily agricultural land was urbanized. Soil contamination research intensified in the late 1980s when soil contamination monitoring was extended from localized areas to a regular programme in order to systematically cover the entire country in 1999. The soils of Slovenia are predominantly contaminated with Cd, Pb, Ni, and Zn only in the hinterlands of limited industrial areas, ironworks, smelters, and coal-fired power plants. Contamination with other heavy metals occurs rarely and in a hot spot pattern. The lack of systematic monitoring of SOM content data in Slovenian soils led to empirical expert knowledge-based spatial modelling to assess areas with a lower/higher potential risk of SOM content decline in agricultural soils. On the contrary, the carbon stocks in soils under forest are presented with data collected during the systematic soil monitoring campaign. Water erosion and wind erosion in Slovenia are neither frequent nor widespread but have been severe under occasional conditions in selected areas. Soil compaction has been studied in soils under forest. Several experiments on the impact of heavy harvesters in undisturbed Cambisols have demonstrated the negative effects of heavy machinery as regards the resulting wheel ruts, even a few years after use has ended.