The occurrence of natural soil microbial communities in rhizosphere of plants used in the management of domestic areas

The objective of the investigation was to observe the effect of selected plants on the development of the population of soil microbes in rhizosphere of these plants. Special attention was paid to microflora of the domestic plants valued as animal fodder and also of great ecological importance in the removal of toxic substances from the environment, e.g. Sida hermaphrodita, Helianthus tuberosus, Konopianka osier, and American osier. Soil samples for microbiological analyses were collected from the rhizosphere and fallow soil in 2003, three times during the vegetation season. The analyses included determination of the total number of bacteria and fungi as well as the number of amylolytic, lipolytic, proteolytic, and ammonification bacteria and were conducted using dilution plate method. The number of cellulolytic and nitrifying bacteria was determined on the basis of the titre. Their most probable number was taken from Mc Crady tables. The content of ammonium nitrogen was determined by the nesslerisation method, nitrate nitrogen by the brucine method, and the respiration activity measured by the amount of liberated CO2 by Ruhling method. Soil reaction was also determined potentiometrically (pH in KCl). Monthly and annual mean values for precipitation, temperature, and relative air humidity in the year of the research have also been presented in the paper. According to the findings, the papilionaceous plants used in the experiment acidified the soil environment, which favoured the development of filamentous fungi. These plants also provided suitable conditions for the development of proteolytic, ammonification, amylolytic, and lipolytic bacteria as well as for the increase of the total number of the bacteria. The greatest amount of liberated CO2 was stated under the aforementioned plants as well as in the rhizosphere of American osier. Both species of osier and Helianthus tuberosus, stimulated the development of cellulolitic bacteria, and American osier stimulated the development of amylolytic bacteria. The greatest number of nitrifying bacteria was stated in the rhizosphere of Sida hermaphrodita, Helianthus tuberosus, and American osier. The greatest amount of ammonium nitrogen was found under Sida hermaphrodita and Helianthus tuberosus whereas the greatest amount of nitrate nitrogen and both forms of nitrogen were found in the soil where the papilionaceous plants and American osier were grown. As the microbiological analyses indicate, the papilionaceous plants, Sida hermaphrodita, Helianthus tuberosus, and American osier had the most positive effect on the development of the soil microbes studied. These plants may be applied to the management of domestic areas and to the improvement of biological activity of degraded soils