Valuation of Biochemical and Microbiological Indicators in Soil Quality Assessment

This thesis research aimed at valuating the suitability of biochemical and microbiological indicators in soil quality and soil health assessment, applying an interdisciplinary approach by means of different methodologies. As the concept of soil quality encompasses both functionality and biological diversity, two cases of study are proposed and each of them aimed at the description of this two aspects. The first case study examined the degree of interference of high soil copper contamination when an old vineyard is converted into a protected area, by investigating the resilience of a polluted soil using biochemical and microbiological indicators. As concerns the second case study, it aimed to describe the interactions between soil physico-chemical parameters, plant growth, and soil microbial diversity under six different agricultural practices, in apple orchards affected by replant disease, by giving an insight into soil microbiological component. Findings of this research confirmed that biochemical and ecophysiological parameters are suitable indicators for soil functioning assessment. Additionally, work revealed that not only extracellular enzymes, but also less abundant microbial populations, seem to play a crucial role in catalyzing ecological processes involved in soil fitness. The investigation of soil biodiversity could better identify specific groups accomplishing a given function. The obtained results demonstrated that also minor populations or still unclassified species could contribute to soil functions by exerting unproportional ecological effects. Furthermore, diverse soil features related to quality assessment, could be properly investigated by applying methodologies which reach different levels of detail. Application of this methodologies could boost a more exhaustive and reliable knowledge concerning the soil mechanisms and, thus, the identification of appropriate soil quality and health indicators.