Mineralogy and Plant Nutrition of Soils that Gained from Rhyolite Rocks in the East of Isfahan

The soils that gained from rhyolite rocks are located in the 115 km from east Isfahan, Central Iran. These soils contain quartz, albit plagioclase, k-feldspar and opaque. Mineralogical study and geochemical investigations suggest that these soils belong to high-kserie. These minerals have very important roal in the plant nutrition. Main oxides including MgO, Al2O3, Na2O, K2O, CaO, FeO and Si2O.These soils in terms of LREE and LILE elements such as Rb, Ba, K, Ceshows many enrichedand depletion in high field strength elements (HFSE) such as Y, Nb and Zr. It has high potassium (K > 4 %wt), rich in iron (FeO / MgO > 3.1) and silica and Nb is less than 70 ppm.Potassium such as N and P is a needed element for plants. The light metabolism is reduced by potassium deficiency, Breathing rate increases and carbohydrates reduced eventually. So potassium has very large role in plant nutrition and it will increase the efficiency of nitrogen fertilizers.