Evolution of some physical properties related to soil quality in the degraded ecosystems of "raña" formations from SW Spain.

The dynamics of some physical properties of the soil: bulk density, porosity and percentage of water stable aggregates, which usually are taken as indicators for evaluation of soil quality, have been studied on the flat surfaces of the Cañamero's "raña" formation (Cáceres, SW Spain). The study shows a high relationship between all these physical soil parameters, the degradation level of the natural vegetation, and years of the soil under tillage. As the deterioration of the natural soil increases the bulk density of the fine earth is increased, diminishing porosity, field capacity moisture content, percentage of water stable aggregates in soil and water infiltration.