EURO-ECO 2010 Hanover 2 - 3 Dezember 2010	Environmental, Engineering - Economic and Legal Aspects for Sustainable Living
	European Academy of Natural Sciences, Hanover European Scientific Society, Hanover University of Bremen, Bremen

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Among the different measures proposed for maintenance or increase of organic matter content in soil organic input on arable land is suggested. Land application of products from organic waste, such as composts is gaining importance all over Europe. This is because such products are often considered beneficial for the soil and at the same time the problem of organic waste streams is alleviated, resulting in environmentally acceptable way of recycling waste materials. It is considered a viable alternative to the landfill or incineration as a disposal method.

Organic amendments activate the autochthonous microorganisms of the soil, and indirectly stimulate the biogeochemical cycles therein, and they provide various minerals (N, P and S) essential for plant nutrition. However amendments not only influence soil fertility directly, but can also affect the composition and activity of soil microorganisms. Soil microorganisms, mainly bacteria and fungi, end their extracellular enzymes, mostly of microbial origin are responsible for the biological transformation that make nutrients available to plants and for sustaining soil function. Since soil microbial communities play a critical role in the recovery of a soil from the disturbance, measurements of the characteristics of microbial community provide invaluable information for soil quality and for a sustainable management of agriculture soils.

A seven years study to investigate the effects of differently treated sewage sludge additions on microbial community structure and microbial processes was carried out in a grey forest soil in the nursery forest. Three types of municipal sewage sludge of the city of Kazan (Tatarstan, Russia) (i.e., anaerobically digested, composted and untreated) were added to field plots of a grey forest soil (Haplic Greyzem) and planted to pine (Pinus sylvestris).

Soil respiration, microbial biomass, N₂-fixation and enzymatic activities were measured as indicators of soil microbial processes. The microbial community structure was evaluated using PCRSSCP approach.

Sewage sludge application in grey forest soil resulted in the increase of metals content in soil and in pine seedlings grown on the amended soil but its concentrations did not reach the current limits of Russia.

The investigation showed that the preliminary sludge treatment can be of key importance for the effect observed. The maximum beneficial effects were found for composted sludge. Addition of the compost to the grey forest soil at different rates (30-175 Mg/ha) improved the organic matter content. The beneficial effects of sewage sludge compost amendment were exhibited in the increase of microbial biomass and respiration. However the N₂-fixation activity of soil was inhibited by the highest rate of compost. It was proved that microbial parameters appear to be the indicators of the effects of sewage sludge in the monitoring of the agricultural soil. Compost application can have impacts on the composition of microbial communities. A new approach for revealing of most efficient system of soil management based on the mathematical modeling of the data obtained for microbial communities was presented.