Effects of topography, climate, mineralogy and physicochemical properties on potassium forms in various soils of Fars province, southern Iran

Abstract

The relationship between potassium (K) and soil physicochemical properties can be used to understand the K cycling. Topography, as a soil forming factor, has an important effect on the soil characteristics of every region. This study was conducted to investigate K and its relationship with climate, mineralogy, and physicochemical properties in toposequences of two regions (Sepidan and Darab) in southern Iran. XRD analysing patterns showed montmorillonite, illite, chlorite, and kaolinite as diagnostic minerals of these regions. Due to being located in arid regions of Iran and lack of good rainfall, the results did not show any significant difference between the selected areas. So, climate could not be considered as an effective factor in supplying K for plants. In both regions, topography affected soil development as a soil forming factor, so that anywhere the more developed soil was observed, the more extracted K forms were found. In different physiographic units of Sepidan region, topography, by affecting soil properties through microclimate, drainage and sunshine quality, caused differences in distribution of K forms. The correlation between different K forms and soil properties in both regions because of weathering and releasing K from K-bearing minerals like illite, showed a relationship with soils finer section.