effect of azotobacter chrococoum and azospirillum lipoferum on the release of soil potassium in pot culture of soybean (glycine max var. williams)

potassium is an essential plant macronutrient. different microorganisms including bacteria, fungi, yeast, algae and mosses are able to decompose silicate minerals of soil and to dissolve nutrient such as k, fe, zn and si, among them bacteria are more important. the aim of this study was to investigate the influence of two bacteria (azospirillum lipoferum and azotobacter chrococoum) on soil available potassium for soybean (glycine max var. williams). the experiment was conducted as a factorial in completely randomized design including three factors with three replications. the first factor includes two different soils, the second factor contains two geniuses of bacteria and without bacterial treatments and the third factor includes two kcl levels (0 and 75 mg.kg-1). to do so, treatments effects on growth and dry weight of soybean were observed over four weeks. result showed that gorgan and ghareso series with azotobacter had the highest plant dry matter. the quantity of potassium uptake by plant was the highest in ghareso series with azotobacter.