Assessing the effects of soil physicochemical properties on aggregate stability and magnetic susceptibility (Case study: Davarn plain of Rafsanjan, Kerman Province)

The main purpose of this research was to study the effect of soil physicochemical properties on aggregate stability and magnetic susceptibility in two aeolian geomorphic units (desert pavement and aeolian clay flat) of Davarn plain in Rafsanjan. After taking 50 samples from the surface soil (0 to 10 cm) of desert pavement and 43 samples of aeolian clay flat, the magnetic susceptibility, mean weight diameter of aggregates and some of their most important physical and chemical characteristics were determined. Results showed that the mean magnetic susceptibility in desert pavement was 842.53 and in clay flat was 632.13 (*10-8 m3 kg-1) which is very high compared to those in soils of Iran and its main reason could be attributed to the parent material of the area. The low mean frequency-dependent magnetic susceptibility in the both study units also confirms this issue. The mean weight diameter of aggregates in the desert pavement varied from 1.20 to 1.93 mm and in the clay flats from 0.54 to 1.80 mm. The findings of this research showed a direct correlation between iron forms (Fed and Feo) with aggregate stability in the both of studied geoforms; however, the level of this correlation was high and significant for Fed. The results also indicated that there is a negative correlation between magnetic susceptibility with electrical conductivity (EC), organic matter (OM) and calcium carbonate equivalent (CCE) in the both of studied units. A positive and significant correlation was seen between total silt, total sand and its fractions with magnetic susceptibility in both geomorphic units. In addition, a negative correlation was seen between the mean weight diameter of aggregates and magnetic susceptibility, which its possible reason can be the presence of a large amounts of sand resulted from aeolian losses and its adverse effects on aggregate stability. The results of regression model indicated that dithionate iron and sand had a significant effect on the magnetic susceptibility; and sand, clay and electrical conductivity had a significant effect on aggregate stability.