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(38-55) Effect of sewage sludge on some microbial and enzymatic activities in the rhizosphere of corn. Abdorhim, H.*,1, Bayoumi Hamuda, H.E.A.F.1, Heltai, G.1, Kecskés, M.1, 1 University of Szent István, Gödöllo, Hungary ABSTRACT- The use of sewage sludge in agriculture as a partial substitute of fertilizers and as an amendment for soil physical properties is a common and seems to be the only environmentally sound practice. In the rhizosphere of corn, some microbial population, spore-forming bacteria, actinomycetes and fungi were counted and identified. Dehydrogenase, catalase, urease, protease, phosphatase and b-glucosidase activities were measured as indicators of soil quality in rhizosphere of corn. In greenhouse, plants were grown for 50 days in pots containing sandy soil mixed with sewage sludge at different rates 0, 10, 20. 30, 40, 50, 60, 70, 80, 90 and 100% (w/w). The experiment was carried out with three replications. The results demonstrated that soil mixed with sewage sludge successfully increased the plant relative dry weight, microbial population and the activities of investigated enzymes at all concentrations. Maximum enzymatic activities were found between 70 and 90% sludge contained-soil, where microbiologically, maximum enumerations were increased significantly by increasing the applied dose of sludge. The ratio between the Gram negative and Gram positive bacteria was 1.58. It is concluded that there are positive effects of sewage sludge when added to the soil on the fertility of the rhizosphere studied at higher concentrations. This means that microbial activity of a rhizosphere and the cycle of important nutrients (e.g., P, N, and C) did not harm by the continuous and gradual addition of sewage sludge to the soil. However, there is still much to be studied about the action mechanisms of sewage sludge in increasing such microbial and biochemical activities in the soil. Key words: biological activities, corn rhizosphere, sewage sludge application |
