Nitrogen rhizosphere influence

R. W. Smiley, Rhizosphere pH as influenced by plants, soils and nitrogen fertili.sers. Soil Science Society of America Journal 38 195 (1974). 

W. Kolb and P. Martin. Influence of nitrogen on the number of Ni-fixing and total bacteria in the rhizosphere. Soil Biology and Biochemistry 20 221 (1988). 

E. Liljeroth, P. J. Kuikman, and J. A. van Veen, Carbon translocation to the rhizosphere of maize and wheat and influence on the turnover of native soil organic matter at different soil nitrogen levels. Plant Soil 76/ 233 (1994). 

Azad, H.R., Davis, J.R., Schnathorst, W.C., Kado, C.I. Influence of Verticillium wilt resistant and susceptible potato genotypes on populations of antagonistic rhizosphere and rhizoplane bacteria and free nitrogen fixers. Appl Microbiol Biotechnol 1987 26 99-104. 

In pure-culture inoculation experiments, made by Rovira (1963), it was found that Azotobacter did not colonize the roots of lucerne, maize, tomato, or wheat to any great extent. Clostridium and a facultative nitrogen-fixing bacillus were moderate colonizers. In mixed-culture, or unsterilized soils, where competition is likely to be very intense, one would expect even less success in attempts to influence the rhizosphere population by adding foreign organisms. 

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