Effect of swine slurry as organic amendment of mine tailings on the establishment of Lolium perenne

Abstract

In Chile, pork production has generated significant income due to the large exportation volume. However, intensive pork production leads to an increase in the production of organic wastes, which may pose environmental problems. Chile is also the largest copper mine producer and the large-scale mines generate massive amounts of tailings which are stored in tailings storage facilities (TSFs). Under the new mine closure legislation, TSFs must be properly closed in order to minimize their environmental impact. This exploratory research was conducted to assess the efficacy for using pig sludge derived from pig slurry treatment plants as organic amendment for the remediation of TSFs. For this, mine tailings were amended with pig sludge at doses of 50, 100 and 200 t ha-1 plus two controls (agricultural soil and unamended tailings). One liter pots were filled with experimental substrates (replicated pots) and maintained in a greenhouse (16°-25° C) for a period of 15 days to allow substrate stabilization through irrigation. They were then seeded with 0.6 g of Lolium perenne (ryegrass) seeds (bioindicator plant), and maintained for a total of 8 weeks. Evaluated variables were aerial and root biomass (fresh and dry), percentage of roots cover, and plant height. Results showed that incorporation of pig sludge into tailings strongly inhibited seed germination, even at the lower dose used, thus resulting in significantly lower plant yield and growth when compared with both controls (agricultural soil and unamended tailings).