Abstract:
Rhizosphere is the area with the most intense microbial activity, under the direct influence of plant species and soil
type. Changes in activity and functional diversity of microorganisms can represent powerful parameters in the analysis
of soil quality. Usage levels of carbon sources by functional groups of microorganisms is found in the changes of
microbial community structure, crop plants stimulating the activity of specific groups. This paper aims to assess the
oscillations of activation / inactivation of microbial functional groups specific in the rhizosphere of soybean, correlating
the activity of whole microbial community with the amount of applied agronomic inputs. Soybean plants were grown
on a phaeosiom argic in the hilly area of Transylvania, experimental field being located in Turda, Cluj county.
Detection plates of microbial activity were inoculated with soil according to the method Microresp and incubated for a
period of 6 hours. Typical soil microbial community present in soybean plants is dominated by α-Ketoglutaric acid.
Codominant of this group in the community are decomposers of D-fructose, L-malic acid and citric acid. Microbial
functional dynamics in unfertilized soil is dominated by microorganisms involved in the nitrogen cycle, enhancing the
accumulation of soil organic nitrogen. Microorganisms from the rhizosphere of soybean crop have a strong reaction to
associated fertilization, zeolite acting as a buffer for disruption caused by the mineral component of fertilizer recipes.
