The Effect Of Leaching Liquid Of Mine Tail Slag And Soil Regulator On Growth Of Grass Plants

There were lots of mine slag stacking in Guangdong Dabaoshan mine, where a lot of ecological and environment problems such as soil and water loss, soil acidification and heavy metal pollution. Mine slag stacking is difficult for the vegetation and ecological restoration. The simplest and economic way to restore tailings soil is phytoremediation, in order to prevent the tailings from regional soil erosion and improve soil environment. But the current difficulty of phytoremediation is lack of suitable plants. In this experiment, I used tailing leaching solution extracted from Dabaosha mountain to examine the effect of tailing leaching solution on six leguminous plants, including Robinia pseudoacacia,Sophora japonica, Sesbania cannabina, Leucaena glauca, Crotalaria pallida, Tephrosia candida. Seed germination rate, germination potential, plant height, root length,aboveground biomass and underground biomass were tested in order to screen out suitable plants to be used for restoration of the mine tailing soils. Then the effects of different doses of soil conditioners(5%?10%?15%)mixed into the tailings soil on the germination rate,germination potential, plant height, root length, aboveground biomass, underground biomass of Lolium perenne, Zoysia japonica, Paspalum notatum and Melinis minutiflora were studied to find the optimal doses of application of soil conditioners to tailings. The study would provide the references for plant species selection and soil conditioners application for the restoration of mine tailing soils. The main results were as follows.(1) The results showed that germination rates of the six leguminous plants were lower than the control at the early germination stage, but the germination rates increased over time. There were significant differences at 7thday germination rates among the six plants,Robinia pseudoacacia being 84%, Sophora japonica, Sesbania cannabina, and Leucaena glauca 38%, 29%, and 26% respectively, Crotalaria pallida and Tephrosia candidawas 9%and 3% respectively. The further analysis showed that germination rates of the sixleguminous plants were significantly affected by varieties but not p H of extract solution of tailings.(2) p H of leaching solution did not significantly affect the root length and plant height,but total affected the biomass and root biomass of Sesbania cannabin,Sophora japonica,Leucaena glauca, and Robinia pseudoacacia. Total biomass and root biomass of Sophora japonica and Sesbania cannabina was higher than the control. Germination rate, plant height, root length, biomass of Robinia pseudoacacia grew better in different p H conditions among the six leguminous plants, which means that Robinia pseudoacacia was suitable as the remediation plant.(3) The results of experiment with soil conditioners showed all the seeds of Lolium perenne, Zoysia japonica, Paspalum notatum and Melinis minutiflora cann't germinate without adding soil conditioners, meaning that all the four grass plants cann't grow in the mine tailing soils under the normal condition.(4) The optimum application rates of soil conditioners to the four grass plants were different. Seed germination rate of Lolium perenne was 32% in the 15% application, while Zoysia japonica and Paspalum notatum were 36% and 14% in 10% application, and dropped to 30% and 0% in 15% application. Melinis minutiflora was only 4% in 5%application. The ranks of germination rates of the four grass plants were Zoysia japonica>Lolium perenne>Paspalum notatum>Melinis minutiflora. Plant height, root length, biomass of Lolium perenne and Zoysia japonica grew better when adding different doses of soil conditioners. 10% dose of the application of soil conditioners may be the best in our experiment.