Pedosphere 15(3): 379--385, 2005
ISSN 1002-0160/CN 32-1315/P
©2005 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Nitrification potential of soils under liquid incubation conditions |
YUAN Fei , RAN Wei and SHEN Qi-Rong |
| College of Resources and Environmental Sciences, Nanjing Agricultural University, Nanjing 210095 (China). E-mail: feyyuan@yahoo.com.cn |
| ABSTRACT |
| A red soil, a fluvo-aquic soil and a permeable paddy soil were used in a long-term investigation to study changes in nitrification with treatments: 1) soil incubation, 2) liquid incubation inoculated with soil samples, and 3) liquid incubation inoculated with ammonia-oxidizing bacteria (AOB) from the soils. There were significant differences (P < 0.001) in nitrification rates among the three soils when measured for 28 days by adding (NH4) SO4 at the rate of 154 mg N k g-1 dry soil to fresh soil. However, the amounts of nitrifying bacteria in the three soils were not related to soil nitrification capacity. When the soil samples or the isolates of AOB enriched from the corresponding soil were incubated in liquid with pH 5.8, 7.0 and 8.0 buffers and 10 mmol L-1 ammonium nitrogen, there were no significant nitrification differences in the same soil type at each pH. The ability to oxidize ammonia through AOB from different types of soils in a homogeneous culture medium was similar, and the soil nitrification capacity could reflect the inherent properties of a soil. Altering the culture medium pH of individual soil type also showed that acidification of an alkaline fluvo-aquic soil decreased nitrification capacity, whereas alkalinization of the acidic red soil and permeable paddy soil increased their nitrification. For a better insight into factors influencing soil nitrification processes, soil properties including texture and clay composition should be considered. |
| Key Words: ammonia-oxidizing bacteria, nitrification, pH, soil type |
| Citation: Yuan, F., Ran, W. and Shen, Q. R. 2005. Nitrification potential of soils under liquid incubation conditions. Pedosphere. 15(3): 379-385. |
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