Study On The Formula For Ecological Substrate Based On Coal Gangue And Its Fertility Characteristic

Coal gangue is the solid waste produced in coal mining and reducing the amount of coal gangue is urgent,therefore,production of ecological substrate with coal gangue is a good way to deal with this problem.In this research,coal gangue was used as raw material along different organic substances to produce ecological substrates for vegetation restoration.An L₁₆（4³）design,i.e.,orthogonal experiment of three factors and four levels,was used in the experimentation,and impact of three raw material factors on substrate properties,including coal gangue particle size（A）,coal gangue content（B）and compost type（C）,were determined.Furthermore,a pot experiment of tall festuca was used to test these results.Using physical and chemical properties of the ecological substrate and plant growth indices,range analysis and variance analysis were conducted to test the significance of the differences among the 16 substrate formulas.Main findings are as follows:（1）Influence of gangue content（A）on plant growth index and substrate nutrient indexes were higher than that of gangue particle size（B）,while the influence of compost type（C）on substrate particle size composition was much higher than the other two factors.The rank of influence for the three factors is:compost type（C）>gangue content（B）>gangue particle size（A）.（2）Coal gangue particle size（A）and coal gangue fraction（B）can significantly affect the contents of major nutrient indices（P<0.01）.Organic matter content increased with the decrease of coal gangue particle size and increase of coal gangue fraction,while total nitrogen and total phosphorus decreased with the decrease of coal gangue particle size and increase of coal gangue fraction,the content of potassium decreased with the increase of coal gangue fraction in the substrate.（3）Among three compost types,sludge compost performed well in terms of organic matter content,total nitrogen and total phosphorus in the substrate due to its high fertilization potential and nutrient richness.In contrast,substrate from topsoil addition owned the lowest nutrient value.However,sludge compost might increase heavy mental content in the substrates and raise the pollution risk.（4）For particle size composition of different substrates,clay particle content of substrate tends to increase with the decrease of coal gangue particle size,while the sludge compost has the highest clay particle content,and the addition of sludge compost can significantly improve the substrate viscosity,which is good for water and nutrients conservation.（5）Germination rate and aboveground biomass accumulation decreased with the increase of proportion of coal gangue in the substrate,or were related to the higher content of heavy metal elements and less nutrition components in the coal gangue.However,both aboveground and underground biomass were significantly affected by composting types（P<0.01）,and substrate made of plant compost was superior in the accumulation of both aboveground and underground biomass.（6）According to the ANOVA results of 17 fertility characteristic indexes,the compost type（C）had significant influence on sand grains（P<0.05）,and the remaining 16 were extremely significant（P<0.01）.Coal gangue content（B）has 3 significant results and 10 extremely significant results.Coal gangue particle size（A）has 1 significant result and 10 extremely significant results.The ecological substrate for the optimal formula obtained through comprehensive evaluation is C₁B₂A₃,that is,40%of plant compost and 60%of coal gangue with 4 orders and below.The results of this study can provide theoretical and technical supports for the application of coal gangue substrates in ecological restoration and regional control of rocky desertification.