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The influence of uncontrolled fertilization of grasscovered arid regions of the Galower Hills (Germany) on microorganisms in the rhizosphere depending on area (valley, higher located hill regions, north and south slope), plant society change, and chemical soil factors has been investigated. Compared with soil of the north slope, an enrichment of organic and anorganic nutrients in different soil samples derived from the south slope could be found. This accumulation is the reason for an increase of soil respiration, biomass, nodulation, and colonization by bacteria and fungi as well as a better development of plants and plant societies, respectively.

A correlation between the lower dry weight of plants from the north slope and a higher population with Streptomyces spp., Penicillium spp. and Mucor spp. of the rhizosphere of wheat and pisum, respectively, could be observed.

One of the consequences of an uncontrolled high amount of liquid manure was the enrichment of the elements nitrogen, phosphorus, potassium and magnesium in the soils. This led to an increased dry weight of plants, especially when they were grown at the north slope and in the subsoil, respectively Since the biological activity was increased, no accumulation of organic carbon compounds in this soil could be found.

A correlation between a higher plant development in the valley and in areas treated with high amounts of liquid manure, respectively, and the colonization of the rhizosphere by microorganisms could be observed: the populations of Pseudomonas spp. and Bacillus spp. were increased, whereas the colonization with Streptomyces spp. and fungi of the genera Fusarium, Penicillium and Mucor were decreased.