Hydrodynamic attributes and potential hydrophobicity of a Typic Hapludult soil under secondary Atlantic forest, degraded pasture and leguminous trees, in Southeastern Brazil

Abstract

Soil physical quality loss is mainly caused by compaction and soil structure deterioration. Both these processes influence water dynamic attributes such as hydraulic conductivity at saturation and sorptivity, as shown in field and laboratory studies with soil aggregates or soil samples preserved inside jackets. This study aimed: (i) to assess the link between different vegetation covers and physical attributes used to describe soil water dynamics and potential soil water repellency; and (ii) to identify whether these attributes recovered after 17-year revegetation with leguminous trees. The experimental area is located in Conceição de Macabú County, Rio de Janeiro State, Brazil. Soil aggregates were applied to tests with a miniaturized tension infiltrometer, allowing to obtain several soil hydrodynamic variables. For the surface horizon, soil hydrophobic behavior did not occur under pasture but occurred under tree covers, with the natural forest and sabiá sites being the highlights. For the subsurface horizon, the natural forest and sabiá sites were classified as non-hydrophobic and the pasture site as hydrophobic, as opposed to what was verified for the surface horizon. For both horizons, the soil under leguminous trees presented results close to those of the soil under forest, and very different from those of soil under pasture. Potential hydrophobicity levels justify the obtained opposite-to-expected hydrodynamic results, such as the lower conductivity and sorptivity occurring despite the lowest compaction and the higher conductivity and sorptivity occurring despite the highest compaction. Therefore, it was concluded that potential hydrophobicity levels affect hydrodynamic attributes and that revegetation using leguminous tree species leads to recovery of the natural soil conditions and perhaps their capacity to exert their original ecological functions.