Soil bacteria microorganisms

Apart from minor sources such as thunderstorms (Section 9.2), atmospheric nitrogen is fixed in Nature by certain soil bacteria, blue-green algae, and microorganisms in the root nodules of legumes. This is accomplished either by oxidation to nitrate... 

Two pathways for nitrogen fixation, a source of nitrogen for plants, (a) Both free-living bacteria in the soil and microorganisms in root nodules produce ammonium ions, (b) Lightning provides the energy needed to form nitrate ions from atmospheric nitrogen. 

The interactions between y-triazines and microorganisms have been studied over nearly 50 years and new research has led to important discoveries. The isolation of pure cultures that are able to modify or completely mineralize y-triazines has led to the discovery of new genes and enzymes that are involved in the degradation and mineralization of y-triazines by soil bacteria. Studies carried out in soils with a history of repeated y-triazine applications indicate that rapid degradation and mineralization of atrazine developed in various soils (Barriuso and Houot, 1996 Bradley et al, 1997 Pussemier et al, 1997). 

That microorganisms can reduce the observed phytotoxic effects of phenolic acids has been observed by a number of researchers.3,7 8 33 37 38 39 41,45 I am, however, not aware of any study that has attempted to quantify how changes in bulk-soil bacteria might influence the phytotoxicity of phenolic acids. I am aware of only one study that has attempted to quantify how changes in rhizosphere microbial populations may influence the phytotoxicity of phenolic acids. Blum et al.9 observed that a 500% increase of phenolic acid utilizing bacteria in the rhizosphere of cucumber seedlings growing in Cecil A-horizon soil enriched with an equimolar mixture of 0.6 pmol/g p-coumaric acid, ferulic acid, p-hydroxybenzoic acid, and... 

There is little evidence of a direct or indirect role or soil bacteria on the dynamics of Cs. Russell et al. (2004) recently reported that bacterial sulfate reduction decreased the adsorption of Cs on arid and tropical soils, but proposed no mechanism. It is unlikely that the accumulation of Cs makes soil microorganisms an important pool for immobilized Cs in mineral soils (because adsorption on soil clays would be much greater). However, this may not be the case in organic soils (Sanchez et al., 2000). 

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