Pedosphere 4(4): 321--329, 1994
ISSN 1002-0160/CN 32-1315/P
©1994 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Effect of ammonium fixation on estimation of soil microbial biomass nitrogen |
| YIN Shi-Xue, FENG Ke, CHENG Chuan-Min, QIAN Xiao-Qing and HU Jian |
| Department of Agronomy, Jiangsu Agricultuml College, Yangzhou 225001 (China) |
| ABSTRACT |
| The effect of ammonium fixation on the estimation of soil microbial biomass N was studied by the standard fumigation-incubation (FI) and fumigation-extraction (FE) methods. NO3-N content of fumigated soil changed little during incubation, while the fixed NH4+ in soils capable of fixing NH4+ increased with the increase of K2SO4-extractable NH4-N. One day fumigation increased both extractable NH4+ and fixed NH4+. However, prolonged fumigation gave no further increase. One day fumigation caused significant loss of NO3-N, while prolonged fumigation caused no further loss. For soils tested, the net increases of fixed NH4+ in fumigated soil equaled to 0-94% of NH4-N flush measured by the FI method, and 1-74% of extractable N measured by the FE method, depending on different soils. It is concluded that the ammonium fixation was one of the processes taking place in soils during fumigation as well as incubation after fumigation and should not be neglected in the estimation of microbial biomass nitrogen by either FI or FE method. |
| Key Words: ammonium fixation, biomass N, fumigation-extraction method, fumigation-incubation method |
| Citation: Yin, S. X., Feng, K., Cheng, C. M., Qian, X. Q. and Hu, J. 1994. Effect of ammonium fixation on estimation of soil microbial biomass nitrogen. Pedosphere. 4(4): 321-329. |
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