Ref ID : 1783
Robert L. Tate III; Variation in heterotrophic and autotrophic nitrifer populations in relation to nitrification in organic soils. Appl.Environ.Microbiol. 40(1):75-79, 1980
Reprint
In File
Notes
The occurrence of heterotrophic and autotrophic nitrifiers in Pahokee muck and the role of these organisms in the ecosystem were assessed by surveying their population densities under different field conditions and by observing the relationship of there populations with aerobic bacteria and soil moisture. Heterotrophic nitrifier populations varied from 2.0x10E5 to 3.8x10E6 bacteria per cm3 of muck in surface fallow (bare) Pahokee muck during the annual cycle. This population decreased 40-fold between the surface and the 60- to 70-cm depths of soil. Similar variations were noted with autotrophic nitrifier populations. Significant correlations were found between heterotrophic nitrifiers and both soil moisture and aerobic bacteria. These relationships did not exist for the autotrophic nitrifiers. In soil that had been heated to kill the autotrophic nitrifiers, while preserving a population of the heterotrophs, and then amended with sodium acetate or ammonium sulfate or both, no nitrate or nitrite accumulated, although significant increase in heterotrophic nitrifiers were detected. In unheated control soil, nitrate plus nitrite-N increased from 14.3 to 181 µg/g of wet soil, and 48 µg of nitrite-N per g was produced. These data suggest that the autotrophic nitrifiers were the sole population responsible for nitrification in Pahokee muck.