土壤压实指标在城市土壤评价中的应用与比较

Application and comparison of soil compaction indexes in the evaluation of urban soils

通过测定南京市不同土地利用下的52个样点的紧实度、容重和孔隙度3个压实指标来反映城市土壤的压实程度。结果表明,南京市大多数土壤存在不同程度的压实,部分压实严重,可能限制植物的生长。不同压实指标在反映土壤压实程度上基本一致,它们之间具有极显著的相关性,可以相互转换。但紧实度指标受到土壤含水量的显著影响。在同一质地或质地相近的土壤,容重和孔隙度可以很好地反映土壤的压实程度。与总孔隙度和毛管孔隙度相比,通气孔隙度在反映土壤压实时更为敏感。所以在进行城市土壤压实状况评价时,可以选择不同的土壤压实程度指标,但就方法的实用性和可靠性来说,容重比紧实度和孔隙度指标一般更方便可靠。

Compaction is ubiquitous in urban soil. This study evaluated urban soil compaction degree by comparing three compaction indexes, i.e., direct compaction measurement (DCM), bulk density (Bd) and porosity (Pr) of 52 soil samples in different land uses in Nanjing City. The results showed that most of the soils in the Nanjing City were compacted, and a high portion of them was severely compacted, which might restrict plant growth. DCM, Bd and Pr were consistent in expressing compaction degree and they had significant relationships, so they could substitute one another. It should be noted that soil water content must be considered when using DCM as a compaction index because water content affects DCM value significantly, which limits the application of DCM. Bd and Pr are affected by texture and organic matter content, but they are good indexes of soil compaction degree when soil texture is similar. Aeration porosity is more sensitive than total and capillary porosity to reflect soil compaction degree. Therefore, different compaction indexes can be used in estimating soil compaction, but Bd is often easier and more reliable than DCM and Pr.