Studies On Soil Physical-chemical Properties And Enzymes Activities For Urban Parks And Roads Green-land In Shenzhen

With soil samples from Shenzhen urban green-land,a research has been carried out into physical-chemical,enzyme activity properties,and their relationship among them,the results show:(1) The texture for both park and roadsideside green-land soils in Shenzhen is loamy clay or clay.The pH value is significantly higher than that of natural soil.The mean value of pH of park soil is lower than that of the roadsideside green-land one,and the acidity of Fairylake Botanical Garden is the highest among them,which is lower than 5.0.There are significantly differences for organic matter and mineral elements,such as N,P,K,in spatial distribution,the general level is low and the effectiveness is poor.Although there are some differences for soil nutrients between the roadside green-land soil and park soil, these differences are not significant.The fertility indexes of park soils are mainly superior to that of the roadsideside green-land soil.(2) The Soil enzyme activity,for instance,acid phosphatase,alkaline phosphatase and catalase in the park soil,is significantly higher in the park soil than that in the roadside green-land soil.There are no significant differences for soil urease,invertase and polyphenol oxidase.The alkaline phosphatase activity in the roadside green-land soil is 125.9%higher than that of the park soil,showing the greatest difference.The neutral phosphatase,acid phosphatase and catalase activitie in the park soil are 24.6%,17.5%, 9.1%higher than that of the roadside green-land soil respectively.(3) There are significant differences of soil respiration rate,microbial biomass carbon and microbial biomass nitrogen among green-land soils,and 19.3%,39.4%and 18.8%for roadside green-land soils higher than those of garden's,respectively.Roadside green-land soils releases more CO₂ to the atmosphere than that of garden's through respiration.(4) Although the relations between soil physical characteristics and other soil indices are not obvious,the relations among different soil enzymes are.The activities of 7 soil enzymes are related to different physical & chemical indices,and microbes to some degree as well.The main factors affected the activities of all kinds of soil enzymes have been obtained by means of path analysis. (5) It is concluded that soil pH,soil nutrients and soil enzymes play a leading role in the soil quality evaluation of park soils and roadside soils,and soil enzymes can be used as indices for soil quality classification evaluation.