Comparing soil physical properties in forest soils and arable soils within heavy-clay Phaeozems: an environmental case study in Romania

The purpose of this paper is to test the hypothesis that the natural soil compaction and its related soil properties in forests are significantly different from the soil compaction in arable soils, under the same climate, relief, geology and soil conditions. This study was carried out in the southern part of the Romanian Plain, during the summer of 2018. The soil contains relatively deep fertile topsoil followed by subsoil enriched in clay. The used methodology consists of digging four pairs of 1.5 m depth soil profiles performed in both forested and arable land, from where both disturbed and undisturbed soil samples were taken and analyzed in the lab. The different environmental conditions and human activities produced modifications in soil physical properties. The results emphasize significant differences between bulk density (BD), other soil physical properties and various soil water content values for the soil matric potential of pF 0, 2.52 and 4.2 in the forest soils, versus the arable soils. The upper part of the soil profile is usually modified in the arable land and soil physical properties worsen. BD was as much as 1.6 kg dm −3 in the topsoil of the arable land, being by 25% higher versus the forested land. However, in subsoil BD is significantly higher in the oak tree forest soils versus the arable soils probably due to the pressure exerted by the permanent thicker tree roots. The potential impact of this research should be regarded in the context of soil management, emphasizing the differences between these two land uses. Thus, for an improvement of the physical properties of arable topsoil and to increase soil carbon sinks by reducing CO 2 deposition in the atmosphere, afforestation for limited periods might be considered.