Relationship Between Soil Potassium Forms and Mineralogy in Highly Calcareous Soils of Southern Iran

Thirty seven soil samples collected from arid and semiarid regions of southern Iran were studied to determine the different forms of potassium and their relation with clay mineralogy and other soil properties. These relationships are very important for understanding K equilibrium and K fertility status of soils. The studied soils had mixed mineralogy and were divided into three groups based on illite percentage of the clay fraction that were 20-35, 10-20 and 0-10% for group 1, 2, and 3 respectively). All forms of K except water soluble K were higher in group one followed with group two and three. Also, significant correlations were obtained between all forms of K and calcium carbonate content, clay content, and CEC. There was a negative significant correlation between calcium carbonate content and different forms of K in each group of soils. These results indicate that reliable estimation of water soluble, HNO -extractable and mineral K content is possible from exchangeable K, clay mineralogy, calcium carbonate content, and clay content