Potassium is a macroelement essential for plants and animals. This element is the main component of some soil minerals and its importance in agriculture has been proven. Iron is one of the major elements existing in the structure of selected micaceous minerals that attracted a lot of attention in agriculture. Gypsum in soil reduces the availability of some nutrients to plants. Although large areas in arid regions of the world, particularly in Iran, are covered with gypsiferous soils, the effect of gypsum on the rate of potassium and iron release from minerals has not yet been studied. The objective of this study was to evaluate the effect of gypsum on the release rate of potassium and iron from phlogopite under laboratory and greenhouse conditions. The results of this study showed that as gypsum content increased, potassium and iron concentrations decreased which is likely due to extensive presence of calcium ions. Potassium and iron release rate from phlogopite was also studied under greenhouse conditions using a completely randomized design with factorial arrangement and three replications. Alfalfa was used as the test plant. The medium was a mixture of quartz sand (as filling material), micacous mineral (phlogopite) and different levels of gypsum. During the six-month cultivation period, the pots were watered and fed with distilled water and four different nutrient solutions including: complete, potassium and iron free, potassium free, and iron free nutrient solutions. Plants were harvested at the end of the growing period and the concentrations of potassium, iron, and calcium of the roots and shoots was measured.The results showed a statistically significant effects of different levels of gypsum on dry weight and potassium and iron concentration and uptake of roots and shoots. In growth media containing gypsum levels of 0%, 2%, and 5% treated with potassium and iron free nutrient solution and potassium free nutrient solution, phlogopite (as a three octahedral mica) was able to provide sufficient amount of potassium for plants. In growth media containing 12% or 25% gypsum treated with either potassium and iron free or potassium free nutrient solution, phlogopite could not provide enough potassium necessity for the plant. This might be due to the high concentration of Ca released from gypsum dissolution. The same results were also obtained for iron. The highest amount of potassium and iron uptake in plant shoot was found in gypsum-free media treated with the complete nutrient solution. Generally, as pH increases due to the presence of gypsum in the medium, potassium and iron uptake by plant decreases as such that the media having 25% gypsum show the highest reduction in potassium and iron uptake. An increase in calcium concentration changes the equilibrium of potassium and iron in the root zone as well as in plant tissues. The results of this study clearly show that the rate of potassium and iron release from micaceous minerals is extremely reduced in the presence of gypsum and, therefore; it is necessary to pay special attention to the nutrient management of these soils.