Response of Wheat to Azotobacter - Actinomycetes Inoculation and Nitrogen Fertilizers

The aim of this research was to investigate the effect of inoculation (Azotobacter chroococcum and actinomycetes) and nitrogen mineral fertilizers (doses of 60 kg N ha-1 and 120 kg N ha-1) on the yield of wheat and on the number and activity of certain microorganisms in rhizospheric soil. The investigation was carried out in humogley soil with three wheat varieties. The variants of the experiment were the following: 1) control (without fertilization or inoculation); 2) A. chroococcum + actinomycetes, ratio 1:1; 3) A. chroococcum + actinomycetes + 45 kg P ha-1 + 45 kg K ha-1 + 60 kg N ha-1); 4) A. chroococcum + actinomycetes + 45 kg P ha-1 + 45 kg K ha-1 + 120 kg N ha-1 ). P, K and 60 kg N were applied in autumn whereas the rest of N was added in spring. The wheat seed was inoculated before sowing. The yield of wheat, the number of azotobacter and actinomycetes, and dehydrogenase activity were determined at the end of the vegetation period. Depending on the variety and type of treatment, the increase of yield was 8-11%. Inoculation and nitrogen fertilizers contributed to the increased number of actinomycetes and azotobacter with all three varieties. Dehydrogenase activity significantly increased in inoculated variants with two varieties (Pobeda and Bg Maksima).