Pedosphere 5(4): 325--332, 1995
ISSN 1002-0160/CN 32-1315/P
©1995 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Nitrogen status and utilization in rhizosphere of rice |
| HUANG Jian-Guo1 and YUAN Ling2 |
1 INRA, Microbiologie, Centre de Nancy, 54280 Champenoux (France)
2 Dept of Soil Science, Southwest Agric. Univ., Chongqing 630716 (China) |
| ABSTRACT |
| A greenhouse pot experiment was conducted with hybrid rice (Oryza Sativa L.) in order to study N status and utilization in the rhizosphere of rice. The experiment was composed of three treatments: without N, 15NH4-N and 15NO3-N. Plant roots were separated from the soil by a nylon cloth, and 1 mm increments of soil, moving laterally away from the roots, were taken and analyzed for various N froms. The labelled N in the plants ranged from 67.51% to 69.24% of the total amount of N absorbed by the rice seedlings with the labelled fertilizer N treatments. This shows that the N in the plants came mainly from the fertilizers. However, the N absorbed by the rice seedlings accounted for less than 35% of the total amount of the N depletion in the soil near the rice roots, indicating an important N loss in the rhizosphere of rice. The soil redox potential (all treatments) and the concentration of the labelled NO3-N (the labelled NH4-N treatment only) decreased as the distance from the rice roots increased in the rhizosphere of rice. In contrast, the concentration of the labelled NH4-N increased as the distance increased in the same soil zone. These results suggested that nitrification occurred in the soil around the rice roots. Therefore, the reason for the N loss in the rhizosphere of rice might be the NO3 movement into the reductive non-rhizosphere soil (submerged) where denitrification can take place. |
| Key Words: nitrification, nitrogen, rhizosphere, rice |
| Citation: Huang, J. G. and Yuan, L. 1995. Nitrogen status and utilization in rhizosphere of rice. Pedosphere. 5(4): 325-332. |
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