Assessing urban soil quality by improving the method for soil environmental quality evaluation in a saline groundwater area of Iran

Changes in the soil quality of urban areas is a critical issue emerging from urban expansion, soil compaction, and other anthropogenic exercises. The evaluation of urban soil quality (USQ) is helpful in landscape and urban planning projects. The present study employed the following USQ models-Cornell Soil Health Test (CSHT) and the Improved Soil Environmental Quality Evaluation (ISEQE) for urban management and planning-to assess USQ in the forest, local, and riverside parks of Ahvaz situated in a saline groundwater area of Iran. The ISEQE model was developed in light of the improvement of the Soil Environmental Quality Evaluation (SEQE) model under the environmental conditions of this area. In this manner, salinity, sodium absorption ratio, compaction, soil structure, and water quality factors were added to SEQE. The parameters of these models were determined on the basis of lab experiments or pedotransfer functions. As indicated by CSHT, average overall quality scores among indicator types in all parks were physical < chemical < biological. Moreover, average overall quality scores among park types were local parks > riverside parks > forest parks, which is believed to be connected with lower aggregate stability, lower water storage capacity, and higher soil hardness due to foot traffic, compaction, and lower organic matter. On the other hand, USQ determined by ISEQE models was in various orders: forest parks > local parks > riverside parks. Differences in the assessment of USQ between CSHT and ISEQE models refer to the selected indices in relation to urban environmental pollution factors for assessing USQ in the ISEQE model. Therefore, soils receiving pollutants will be of a lower quality. In this study, the USQ of the local parks with higher vegetation cover was less than that of the forest park as a result of high concentrations of heavy metals in the local parks. In light of field observation, the ISEQE model was the most effective model to assess USQ. Consequently, the ISEQE model can be helpful in determining USQ for green space management in Ahvaz.