A pot experiment with mixtures of slate processing fines and compost

Mixtures of slate processing fines (SPF), produced in the slate industry, and grape marc vermicompost (GMV) were evaluated as an artificial soil to be spread over the top surfaces of slate dumps as a support for a permanent vegetal cover. The SPF and GMV were mixed in four doses (2, 4, 8 and 16% GMV, dry weight, four replicates) and sown with Italian ryegrass (Lolium multiflorum Lam.). After fourteen weeks in a greenhouse, plant productivity and changes in physical, chemical and biological properties of the mixtures were determined and statistically evaluated by means of ANOVA and the Duncan's test. The nutrient contents of the SPF and their plant productivity were significantly increased since the lowest addition of GMV, as well as their biological activity. Also, water-holding capacity and the Atterberg's limits, defining consistency, were increased. In conclusion, these mixtures could be employed as artificial soil to decrease the environmental impact caused by the dumps in open cast mining activities, improving soil quality and helping to establish a permanent vegetal cover as a first step to reclamation.