Pedosphere 17(3): 383--388, 2007
ISSN 1002-0160/CN 32-1315/P
©2007 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Dynamics of microbial activity related to N cycling in Cd-contaminated soil during growth of soybean |
YANG Ye1,2 , CHEN Ying-Xu1, TIAN Guang-Ming1 and ZHANG Zi-Jian1 |
1 Department of Environmental Engineering, Zhejiang University, Hangzhou 310029 (China). E-mail: yeyang@acee.org.cn
2 Appraisal Center for Environment and Engineering, SEP, Beijing 100012 (China) |
| ABSTRACT |
| The potential influences of cadmium (Cd) on the biochemical processes of the soil nitrogen (N) cycle, along with the dynamics of ammonification, nitrification, and denitrification processes in the rhizosphere and non-rhizosphere (bulk soil), respectively, were investigated in a Cd-stressed system during an entire soybean growing season. In terms of Cd pollution at the seedling stage, the ammonifying bacteria proved to be the most sensitive microorganisms, whereas the effects of Cd on denitrification were not obvious. Following the growth of soybeans, the influences of Cd on ammonification in the bulk soil were: toxic impacts at the seedling stage, stimulatory effects during the early flowering stage, and adaptation to the pollutant during the podding and ripening stages. Although nitrification and denitrification in the bulk soil decreased throughout the entire growth cycle, positive adaptation to Cd stress was observed during the ripening stage. Moreover, during the ripening stage, denitrification in the bulk soil under high Cd treatment (20 mg kg-1) was even higher than that in the control, indicating a probable change in the ecology of the denitrifying microbes in the Cd-stressed system. Changes in the activity of microbes in the rhizosphere following plant growth were similar to those in the non-rhizosphere in Cd treatments; however, the tendency of change in the rhizosphere seemed to be more moderate. This suggested that there was some mitigation of Cd stress in the rhizosphere. |
| Key Words: cadmium, microbial activity, nitrogen cycle, rhizosphere |
| Citation: Yang, Y., Chen, Y. X., Tian, G. M. and Zhang, Z. J. 2007. Dynamics of microbial activity related to N cycling in Cd-contaminated soil during growth of soybean. Pedosphere. 17(3): 383-388. |
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