Persistence and intensity of soil water repellency from soils with andic properties from the Campania region (Southwest, Italy) under different forest types

Abstract

Soil water repellency (SWR) is a property of many soils that is getting more and more interesting for the scientific community, because of its consequences on soil erosion risk, runoff or infiltration rates and even plant ecology. The presence of hydrophobic organic acids released by roots and plant tissues, fungal activity, organic matter mineralization rates, or wildfires are considered the main causes of SWR. Some of the consequences of SWR are reduced soil infiltration rates, enhanced runoff flow and soil erosion. Significance of these effects depends upon the severity and spatial variability of SWR. SWR is often associated to vegetation types, although it cannot be assumed that certain species always induce water repellency under natural conditions. Because of resins, waxes and aromatic oils in their tissues, evergreen trees as eucalyptus and coniferous are usually associated with soil hydrophobicity, although it has been found also in a variety of soils, climates and vegetation types. But the relationship between water repellent soils and plant species is not always one-to-one. Soil properties as texture, aggregation, acidity, microbiome and other are also implied in the development of hydrophobicity. Regarding organic matter, several authors have reported inconsistent results after studying the relationship between soil organic matter content and SWR. A possible explanation for this is that quality of organic matter is more important than content. Consequently, it is necessary to investigate the role that organic matter content and properties play in the development of hydrophobicity in different soil and vegetation types. The objective of this research is the study the relationship between SWR and organic matter properties in andic soils from the Campania region (SW Italy) under different vegetation types.