COMPARING PHYSICAL QUALITY OF FOREST AND PASTURE SOILS IN A SICILIAN WATERSHED

Forest and pasture soils should have differing properties due, for example, to differing root characteristics or livestock trampling rates, but contradictory results are reported in the literature. The surface soil physical and hydraulic properties of five forest and pasture sites were determined in a Sicilian watershed. In general, forest soils had a significantly lower bulk density, b (by 17 to 35%), and a higher field saturated hydraulic conductivity, Kfs (by a factor of 3.4-11.5) than pasture soils. Differences between water retention characteristics of forest and pasture soils were low when high levels of organic matter, OM, content (> 7.1%) were detected for both land uses. The mean Kfs varied with the amount of large pores (i.e. larger than 596 or 298 m) in the soil. Means of Kfs also increased with OM and decreased with an increase in b (coefficient of determination 0.69-0.74). According to existing guidelines to evaluate soil physical quality, a good or relatively good forest soil quality was a common result. In three sites, a worse pasture soil physical quality was detected in comparison with the forest. In conclusion, changing land use from pasture to forest should have a favorable impact on hydrological processes in the sampled watershed, due to a better physical quality of forest soils. The order of magnitude of the mean Kfs was predictable using laboratory data. The applicability of the existing guidelines to assess soil physical quality was indirectly supported in this investigation, because a better quality was expected for the forest soils than the pasture ones.