| The application of green roof provides a good way to solve the shortage of urban greening land resources and improve the urban ecological environment.At present,traditional peat substrate is the common green roof substrate in China,but the overexploitation and utilization of peat resources will inevitably lead to the destruction of wetlands and exhaustion of peat resources in recent years.With the requirements of ecological civilization and sustainable development,the search for alternative substrates for peat has become a research hotspot.The application of green roof substrates in foreign countries focuses on the recycling of solid waste,and has achieved good results in the research of construction waste(broken bricks,clay,etc.)and organic waste(greening waste,waste paper,etc.).In China,there is still in its infancy in the application of greening waste on green roof substrates.There are also problems,such as less practical applications,irregular substrate ratio,and shorter research time.For further study the application of greening waste compost on green roof substrate,this study replaced partly/wholly traditional peat substrate with the greening waste compost mixed with inorganic substrate(volcanic rock and vermiculite),four sets of tests were conducted including the comparison of physical and chemical properties of the substrates,chemical properties stability test,water retention and plant planting experiment on roof.Based on the comprehensive evaluation of membership degree and principal component analysis method,the substrate formula which is most beneficial to plant growth was selected.The results showed that:(1)under the roof environment conditions,each treatment experienced one year of growth of Sedum lineare and Sedum aizoon,showing good chemical stability in general.Its pH,organic matter,total nitrogen,total phosphorus,total potassium and C/N value were relatively stable and increased partially,and its electrical conductivity and cation exchange capacity value firstly decreased significantly and then stabilized.(2)greening waste compost has good storage capacity,thermal stability and water retention,The treatment T4 has the highest comprehensive ranking in all three respects.(3)the growth rate of Sedum lineare and Sedum aizoon,which grew in greening waste composting substrates,was faster than that of traditional peat substrate,and had certain growth index advantages and good resistance to stress.The optimal substrate formula were treatment T3 and treatment T4,ie v(greening waste compost):v(inorganic substrate)=80:30 and v(greening waste compost):v(inorganic substrate)=65:35,where the inorganic substrate ratio was v(volcanic rock):v(vermiculite)=3:2.(4)the greening waste compost substrates met the load requirements of green roof,and it played an important role in improving the acidity,alkalinity and the nutrient balance of the substrates.This study mainly compared and analyzed the physical and chemical properties,chemical property stability,water retention performance and plant growth of greening waste compost substrate and traditional peat substrate,which providing theoretical and practical experience for the application of greening waste compost in green roof substrates. |
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