Maize is an important field crop which is mainly grown in the system of conventional production accompanied by the use of mineral fertilizers. Organic maize production is not widespread but it has been getting more attention recently. The aim of the research was to determine the effect of azotobacter on the microbiological activity in the rhizosphere and on the grain yield of various maize hybrids grown in the system of organic production. The experiment was conducted in field conditions at the Institute of Field and Vegetable Crops, Department of Organic Agriculture and Biodiversity in Backi Petrovac. Four maize hybrids (ZP 555 su, NS 609b, 620k and NS 6030) and three concentrations of Azotobacter chroococcum were used. The grain yield of maize was determined at the end of the vegetation period. The number of azotobacter, the number of aminoheterotrophs  and dehydrogenase activity  in the rhizospheric soil were determined, too. The grain yield increased in the variants with azotobacter. The greatest increase in the grain yield was recorded in ZP 555 su hybrid and it amounted to 1000 kg/ha. In NS 6030 hybrid, the increase in yield amounted to 280 kg/ha and in 620k it amounted to 450 kg/ha. In NS 609b hybrid, there was no effect. The use of azotobacter did not significantly affect the number of azotobacter or aminoheterotrophs. Dehydrogenase activity increased in the variants with azotobacter. The paper presents preliminary results of the research conducted during one year. Therefore, no final conclusions can be drawn. Still, the results indicate in which direction further research should be done.

Azotobacter chroococcum, maize, yield, number of microorganisms.

Presentation: oral