Study on Soil Porosity and Water Characteristics of Urban Green Space in Shenzhen City

In order to understand the physical properties of strongly human-affected soil in urban green space,and give guidance for exerting its functions for promoting plant growth,conserving water resources and protecting urban eco-environment.Soil bulk density,porosity status,water parameters and water infiltration characteristic for urban green space in Shenzhen City were determined.The results indicated that the bulk density of urban green space soil in Shenzhen City was high,with an average of 1.56 g/cm 3 .The soil total porosity,capillary porosity and aeration porosity were low,41.06%,39.78% and 1.27%,respectively.Significant variation of soil infiltration rate was observed in the initial infiltration rate (0-8.47 mm/min)and the final infiltration rate(0-5.90 mm/min),which were related to compaction of urban soil.Soil bulk density in urban park and roadside greenbelt were significantly higher than those of vegetable garden in suburb,but the soil porosity,maximum water-holding capacity,capillary moisture capacity and field moisture capacity were significantly lower than those of vegetable garden.The soil bulk density and water parameters in 0-10 cm depth were significantly higher than those in 10-20 cm depth,however,soil porosity showed different trend.There were significantly negative correlations between soil bulk density and soil porosity,field moisture capacity,maximum water-holding capacity,the initial infiltration rate and the final infiltration rate.