EFFECTIVENESS OF INOCULATING BARLEY WITH AZOSPIRILLUM-BRASILENSE AS DEPENDENT ON THE APPLICATION RATE OF POTASSIUM FERTILIZERS

The effect of various doses of potassium on the density and nitrogenas e activity of a population of Azospirillum brasilense inoculated into soil was studied in vegetative experiments with barley. It was shown t hat, at 120 mg KCl/kg soil, the survival and nitrogenase activity of t he introduced strain in the rhizosphere reached maximum values. Increa sing the KCI dose to 320 or 640 mg/kg caused a sharp decrease in the c ell number and activity of azospirilla. The influence of potassium nut rition on the composition of root exometabolites, which create a pecul iar ecochemical zone in the rhizosphere, is discussed. It is shown tha t one of the reasons for the poor survival and low effectiveness of in troduced nitrogen fixers can be high potassium content in the soil.