Soil tillage and compost amendment promote bioremediation and biofertility of polluted area

The risk for human health and environment due to the presence in agricultural soils of organic and inorganic contaminants derived from illegal waste disposal, posed the need to develop a sustainable strategy for the restoration of soils with high agricultural potential. In this study an eco-compatible method as soil tillage and compost amendment was applied in two sites of a National Interest Priority Site of Campania Region (Italy) known as “Terra dei Fuochi”. After one year, the concentration of heavy hydrocarbons (C > 12) significantly reduced in a range from 84 to 95%, probably due to the aeration causing photo-oxidation processes and an improvement of microbial activity able to degrade organic pollutants. Although a reduction trend was observed, the potentially toxic elements (PTEs) concentration in soils was unmodified indicating a potential risk of plant uptake. The high-throughput sequencing approach used to explore the response of native microbial populations following in situ treatments showed that microbiota dynamic was differently affected in the two sites. Therefore, the characteristics of the sites could differently interact with compost determining a different microbial response. Alphaproteobacteria (incidence range of 14-18%), Actinobacteria (incidence range of 10-22%) and Sordariomycetes (incidence range of 23-57%) were the dominant autochthonous populations in all soils indicating their high adaptability to different environments and high resistance to environmental stress as well as their high potential in degradation of organic xenobiotic compounds. The remediation practices based on soil tillage and compost amendment promoted the restoration of the microbial biofertility of soils affected by spotted multi-contamination, to bring them back to agricultural use.