Pedosphere 4(4): 311--319, 1994
ISSN 1002-0160/CN 32-1315/P
©1994 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| A method for determining available fixed ammonium in soils |
| CHENG Li-Li1, WEN Qi-Xiao2 and LI Zhong-Pei1 |
1 Department of Soil Biochemistry, Institute of Soil Science, Academia Sinica, P. O. Box 821, Nanjing 210008(China);
2 LMCP, Institute of Soil Scienca, Academta Sinica, P. O. Box 821, Nanjing 210008 (China) |
| ABSTRACT |
| Dynamics of fixed NH4+ in NH4+-treated soils incubated with glucose at 37±2 ℃ during the course of incubation and factors affecting it were studied. Results showed that content of fixed NH4+ in soil reached a minimum on day 7 after incubation and then increased gradually regardless of the amount of glucose added and the kind of soil tested. However, the amount of fixed NH4+ released from the soil at the given time varied with both the amount of glucose added and the kind of soil examined. In cases glucose was added at a rate of 10.0g C/kg soil, the amount of fixed NH4+ retained in soil after 7 days of incubation was almost identical to that found by Neubauer test. Addition of K+ depressed the release of fixed NH4+ significantly. Based on the results obtained a method for determining the content of available fixed NH4+ in soils was proposed and the amount of N as available fixed NH4+ in two soils measured by this method on an area profile-depth basis was presented. |
| Key Words: available fixed ammonium, defixation, incubation, nitrogen immobilization |
| Citation: Cheng, L. L., Wen, Q. X. and Li, Z. P. 1994. A method for determining available fixed ammonium in soils. Pedosphere. 4(4): 311-319. |
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