An integrated approach to studying the genesis of andic soils in Italian non-volcanic mountain ecosystems

- Andosolization is the main process affecting pedogenesis.
- Soils at highest latitudes have high analytical proximity with underlying bedrock.
- Soils at lowest latitudes have volcanic fingerprint.
- PSD analysis identifies great soil homogeneity with a fine silt aeolian component.

Over recent decades, andic soils have been increasingly found in non-volcanic mountain ecosystems (NVME) in many parts of the world. In Italy, this type of soil has proved to be greatly affected by aeolian deposits and to be widely distributed geographically.However, there are still many open questions, especially regarding the genesis of these soils. This paper focuses on five representative pedons taken from NVME. Soil forming processes and relationships between soil and underlying bedrock were investigated by using an integrated approach including geochemical, magnetic, mineralogical, micromorphological and particle size distribution (PSD) analysis. The 5 pedons showed andic character and similar morphology and micromorphology (e.g. silt illuviation, pedorelicts), as well as large differences in terms of soil reaction and clay mineralogy. The analysis of the vertical distribution of C, Al and Fe extracted in pyrophosphate along with related geochemical indices (e.g. Cp/Alp) enabled us to indicate andosolization as the main process of soil formation and to exclude podzolization. With respect to the soil-bedrock relationship, 2 soils showed great similarity to the underlying bedrock along with a clear aeolian particle size distribution footprint, whereas, in the remaining 3 soils, there was a clear soil-bedrock discontinuity and an evident volcanic fingerprint. Some of the soil-bedrock differences related to the geographical settings and latitude.