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Effects of Available P and N:P Ratios on Non-Symbiotic Dinitrogen Fixation in Tallgrass Prairie Soils
K. A. Eisele, D. S. Schimel, L. A. Kapustka and W. J. Parton
Vol. 79, No. 4 (1989), pp. 471-474
Stable URL: http://www.jstor.org/stable/4218983
Page Count: 4
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Prescribed burning is a major control over element cycles in Tallgrass prairie (Eastern Kansas, USA). In this paper we report potential effects of fire on non-symbiotic nitrogen fixation. Fire resulted in additions of available P in ash, which may stimulate nitrogen fixation by terrestrial cyanobacteria. Cyanobacterial nitrogenase activity and biomass responded positively to additions of ash or P in laboratory assays using soil. Further assays in soil showed that cyanobacteria responded to changes in available N: available P ratio (aN: P) across a range of concentrations. Nitrogen fixation rate could be related empirically to aN: P via a log-linear relationship. Extrapolation of laboratory results to the field yielded a maximal estimate of 21 kg N ha-1 y-1. Results support arguments from the marine and terrestrial literature that P availability is central to regulation of ecosystem N budgets.
Oecologia © 1989 Springer