Zeolitized tuffs in pedotechnique for the reclamation of abandoned quarries. A case study in the Campania region (Italy)

The present study aims to assess the evolution of different proto-horizons as embryonic soils built by pedotechnologies for the reclamation and management of derelict and damaged lands, such as abandoned quarries. The model proto-horizons were assembled by utilizing coarse limestone gravel or zeolitized Phlegraean Yellow Tuff (PYT) as mineral components and commercial compost-amendments or a phosphorite-poultry manure mixture as organic matrices for growth of a pasture-grass under controlled conditions. The evolution of the model proto-horizons was followed by an evaluation of the stability and modification of the organic matter (OM) with reference to plant development. The results suggest that the natural carbonatic substrate occurring in limestone quarries was unable to sustain significant plant growth, while the PYT was suitable and efficient as a pedogenic substrate because it supported plant growth and induced a conspicuous accumulation of OM due to root activity. In particular, OM, including humic and non-humic components, greatly increased in the PYT treatment with the phosphorite-poultry manure mixture showing a concurrent trend toward humification. Conversely, an overall tendency toward degradation of OM was detected in the PYT model proto-horizon treated with commercial compost. Feasibility estimates show that quarry restoration costs appear reasonable where environmental impacts are high.