Pedosphere 4(2): 145--152, 1994
ISSN 1002-0160/CN 32-1315/P
©1994 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Mitrification-Denitrification Loss of Added Nitrogen in Flooded RiceRhizosphere |
| LI XIN-HUI1, ZHU ZHAO-LIANG1, CAI GUI-XIN1, ZHOU KE-YU1, CAO YA-CHENG1 |
| Institute of Soil Science, Academia Sinica, P.O .Box 821 . Nanjing (China) |
| ABSTRACT |
| Nitrification-denitrification losses of 15N-labelled nitrate and ammonium applied to the rhizosphere and nonrhizosphere of flooded rice were evaluated in 2 greenhouse rhizobox experiments. The loss of added N via denitrification was estimated directly by measuring the total fluxes of (N2O+N2)-15N. It was found that 67% and 51%-56% of ESN-nitrate added to rice rhizosphere were lost as (N2O+N2)-15N in the 2 experiments, respectively,which were comparable to that added to nonrhizosphere soil (70% and 47%, respectively), implying that the denitrifying activity in rice rhizosphere was as high as that in nonrhizosphere soil. However, only tracx amounts (0-0.3% of added N) were recovered as (N20+N2)-15N when ESN-ammonium was applied to either rhizosphere or nonrhizosphere, which seems to indicate that the nitrifying activity in the either rhizosphere or nonrhizosphere soils was quite low. The apparent denitrification calculated from 15N balance studies was 10%-47% higher than the total flux of (N2O+N2)-15N. Reasons for the large differences can not be explained satisfactorily. Though the denitrifying activity in rhizosphere was high and comparable to that in nonrhizosphere soil, presumably due to the low nitrifying activity and/or the strong competition of N uptake against denitrification, the nitrification-denitrification taking place in rhizosphere could not be an important mechanism of loss of ammonium N in flooded ricesoil system. |
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| Citation: Li, X. H., Zhu, Z. L., Cai, G. X., Zhou, K. Y. and Cao, Y. C. 1994. Mitrification-Denitrification Loss of Added Nitrogen in Flooded RiceRhizosphere. Pedosphere. 4(2): 145-152. |
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