Chemical Forms and Quantity-Intensity Relationships of Potassium in Rafsanjan and Anar Lands under Pistachio Trees

Quantity-intensity parameters provide practical information about potassium availability. Limited information about quantity-intensity relationships in Rafsanjan and Anar regions under pistachio orchards is available. So that this research was conducted to study the status and chemical forms of potassium using common extractants and also study the quantity-intensity relationships. For this purpose in 20 soil samples that were taken from Rafsanjan, Anar, Nough and Kabootarkhan, soil potassium was extracted using ammonium acetate, sodium acetate, 0.01M calcium chloride, 0.1 M nitric acid, 2M sodium chloride, water and boiling nitric acid extractants and chemical forms of potassium and their correlation with leaf potassium concentration were determined. Results showed that amount of soluble potassium in these soils is between 33.9-193.6, exchangeable potassium was in the range of 71.8-683.6 and nonexchangeable potassium was in the range of 250.1-1112.6 mg kg-1. None of these extractants had significant correlation with leaf potassium concentration of pistachio trees. Mineralogical analysis indicated that montmorilonite, illite, chlorite, kaolinite and paligorskite are dominant minerals in this region. Quantity-intensity relationships revealed that the potential buffering capacity (PBC) is in the range of 30.685-78.758, the rang of activity ratio in equilibrium (ARke) is 0.002-0.022 and the readily exchangeable potassium (DK) is in the range of 0.0885-1.66 in studied soils. DK parameter showed a significant correlation with soluble, exchangeable and nonexchangeable forms of potassium. ARke parameterwas correlated with soluble and exchangeable forms significantly but PBC parameter had no correlation with chemical forms of potassium and soil characteristics.