Physical Soil Quality Evaluation of a Part of Beheshtabad Sub-basin in Chaharmahal va Bakhtiari Province

The soils of the Shahrekord plain, part of the Beheshtabad watershed subbasin in Shahrekord County, Chaharmahal va Bakhtiari province, have been used for crop production and domestic animal feeding for centuries, yet the soil quality of this plain has been overlooked.Therefore, assessing the quality of Shahrekord plain soil is essential.This research aimed to evaluate the physical soil quality of the plain using soil quality indices such as the Integrated Quality Index (IQI) and Nemoro Quality Index (NQI).A randomized compound sampling strategy was employed, and 106 surficial (0-25 cm) soil samples were collected during intensive fieldwork.Following pretreatments of the soil samples, several key soil characteristics were measured using standard methods, which were compiled into a Total Data Set (TDS) and used to calculate IQITDS and NQITDS.The minimum effective data set (MDS) was selected, and weights for the quality indices were determined using TDS and Principal Component Analysis (PCA).The minimum data set included the soil sand percentage, soil organic matter percentage, mean weighted diameter of aggregates, soil moisture at field capacity, bulk density, soil reaction, and electrical conductivity.The soil quality at each sample site was assessed using the indices and data sets, TDS and MDS.Geostatistical techniques and ordinary kriging methods were utilized to map soil quality.Results indicated that the soil quality of rangelands was significantly higher than that of cultivated soils (irrigated and drylands).Additionally, approximately 71% of the soils were classified as very low, low, and medium quality, highlighting the need for monitoring and managing such soils.