ability of barley (hordeum vulgare l.) to take up potassium from di- and tri-octahedral micas

abstract mineral weathering is a major source of most essential nutrients including potassium. it is well known that potassium plays an important role in improving the quality of agricultural products and micaceous minerals, as the major source of potassium, are abundant in iranian soils. no information is available on the role of micaceous minerals in supplying k to barley as the second major crop in iran. the objective of this research was to demonstrate the ability of barley (hordeum vulgare l.) to take up structural potassium from muscovite and phlogopite. the experiment was carried out in a completely randomized design with factorial combinations and three replicates. culture medium was a mixture of quartz sand (as filling material) and k-bearing minerals including muscovite or phlogopite. pots were irrigated with different nutrient solutions (+k and -k) during a period of four months. barley govhar cultivar was used which is widely cultivated in the isfahan province. at the end of experiment, shoots and roots were separated and plant samples were prepared with dry ashing method and their k content was determined with flame photometer. in k-free treatments, total plant k uptake was significantly higher in phlogopite treated medium as compared to muscovite. no significant difference was found between control and muscovite amended treatment under k-free solution. in pots amended with phlogopite, k concentration was in sufficient limit, even under k-free nutrient solution. this indicates the importance of the type of micaceous minerals in plant k availability, particularly in soils where minerals structural k is the only source of k supply.