Occurrence of Azotobacter spp. in cultivated soils in Poland

Abstrakt

Azotobacter spp. are soil bacteria capable of fixing atmospheric nitrogen and making it available to plants. This makes them microorganisms of hight importance to the agriculture. The distribution of these bacteria is a complicated subject and is correlated with diverse factors, witch determine the presence or absence of the bacteria in a specific soil. The soil properties as soil and fertility and climate conditions affect the abundance of diazotrophs. Research material consisted of 182 soil samples taken in 2015 from agricultural land in various voivodeships. The number of Azotobacter spp. was determined based on plate method. The presented study evaluated the abundance of Azotobacter spp. in various Polish soils and confirmed the relationship between soil properties and the presence of these bacteria. The studied bacteria were present in 37% of soil samples and numbers of these bacteria varied widely, from 3 to 10801 cfu g-1 of the soil. In the case of Azotobacter spp., soil acidity was also an important factor restricting the occurrence of these bacteria in soils.