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 avai...