Original Research Polish J. of Environ. Stud. Vol. 16, No. 6 (2007), Introduction Municipal sewage sludge, frequently referred to as biowaste, is created during the process of treatment of municipal sewage as a waste of various composition and physico-chemical and biological properties. Organic wastes have accompanied human beings from the very beginnings of existence. In Poland, like in all other coun- tries of the European Union, there is a serious problem of sewage management. Depending on the quality and quantity of the pro- duced wastes as well as local conditions, there are differ- ent methods of handling wastes. These methods include, among others, storage in waste dumps, burning, agricul- tural utilization or dumping them into the sea. The share of different methods employed in the pro- cess of waste management changes. Dumping of wastes into the sea as well as their storage in landfills is increas- ingly restricted. Therefore, bearing in mind the fertiliza- tion value of sewage sludge, it appears quite sensible and justified to utilize it for agrotechnical purposes [1-9]. The application of sewage sludge to agricultural land does not only provide a convenient method for the dispos- al of a waste product, but it also has the beneficial aspect of adding valuable plant nutrients and organic matter to the soil [10, 11]. The origin of sewage sludge makes it similar to the soil humus in that it contains carbon and nitrogen organic compounds which are essential for the lives of soil micro- *Corresponding author; e-mail: amaruwka@au.poznan.pl Effect of Fertilization Using Communal Sewage Sludge on Respiration Activity and Counts of Selected Microorganisms in the Grey Brown Podzolic Soil A. Wolna-Maruwka*, J. Klama, A. Niewiadomska Department of agricultural Microbiology a. Cieszkowski agricultural University in Poznań, ul. Szydłowska 50, 60-656 Poznań, Poland Received: October 4, 2006 Accepted: July 10, 2007 Abstract The objective of the performed investigation was to ascertain the impact of different doses of sewage sludge (2t, 4t and 8t d.m. sewage sludge·ha -1 ·year -1 ) on the developmental dynamics of oligotrophic, copio- trophic, cellulolytic and proteolytic microorganisms. Soil samples for microbiological analyses were collected at six dates connected with the developmental phases of spring barley. The incorporation into the soil of organic matter in the form of sewage sludge resulted in a slight in- crease in the counts of all the analyzed groups of microorganisms. The performed statistical analysis showed a positive correlation between the intensity of the CO 2 release and numbers of the discussed microorganisms in all fertilization treatments. Keywords: microorganisms, respiration activity, soil, sewage sludge, spring barley 899-907