Evaluation of the role of biological properties in the soil quality of the Hanam sub-basin of Lorestan province

The application of soil quality (SQ) in sustainable land management is evolving. However, despite their considerable importance, the inclusion of biological properties in soil quality assessments is limited due to the challenges and high costs associated with measuring these attributes. This study was carried out on the contribution of biological properties to soil quality. In this research, 22 physical, chemical, and biological properties of 90 surface soil samples (0-30 cm) were analyzed to determine the soil quality index (SQI) in the Honam region of Lorestan. Analyzed properties included pH, electrical conductivity (EC), organic carbon (OC), total neutralizing value, clay and silt content, microbial biomass carbon (MBC), basal microbial respiration (MR), the total fungal and bacterial populations, the populations of Azotobacter and Pseudomonas species, as well as the activities of urease, acid and alkaline phosphatase, the available potassium and phosphorus concentrations, the total nitrogen, and the content of manganese, iron, copper, and zinc. Principal component analysis (PCA) to select a minimum data set (MDS) revealed that eight principal components, each with eigenvalues greater than one, accounted for 89.83% of the total variance. Of the 22 soil properties 12 were selected for the MDS, with biological properties (5 properties) making a more significant contribution than the physical and chemical properties. The spatial distribution of the SQI underlines the significant influence of biological properties on soil quality. These results underline the importance of including biological properties in the assessment of soil quality.