Pedosphere 12(1): 15--31, 2002
ISSN 1002-0160/CN 32-1315/P
©2002 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Nitrogen mineralization of prunings of six N2-fixing hedgerow species in a dry valley of the Jinsha River |
SUN Hui1,2 , TANG Ya2 and ZHAO Qi-Guo1 |
1 Institute of Soil Science, the Chinese Academy of Sciences, Nanjing, 210008 (China);
2 Chengdu Institute of Biology, the Chinese Academy of Sciences, Chengdu 610041 China) |
| ABSTRACT |
| A litterbag experiment of 12 weeks was conducted to study nitrogen mineralization process of prunings of six nitrogen-fixing hedgerow species in a dry valley of the Jinsha River. Prunings were incorporated into soil or used as mulch. The results indicated that pruning N of the six hedgerow species was mineralized fast in the first week and then decreased slowly in the rest of the study period. When prunings were incorporated into soil, the amount of nitrogen mineralized by the end of the first week accounted for 69.9%, 58.2%, 54.5%, 43.0%, 29.6% and 20.6% of the total N in prunings of Desmodium rensonii, Tephrosia candida, Leucaena leucocephala, Albizia yunnanensis, Acacia dealbata, and Acacia mearnsii, respectively. When prunings of L. leucocephala were used as mulch materials, the amount of nitrogen mineralized in the first week was 16.2% less than that of prunings incorporated into soil. The mineralization pattern of pruning N could be simulated by an exponent model Nt% = N01% (1 -exp(-k1t)) + N02% (1-exp (-k2t)) where Nt% is cumulative mineralized N in time t, N01% and N02% are readily and less readily mineralizable N in prunings, respectively, and k1 and k2 are rate constants. A half-life period of pruning nitrogen mineralization could also be determined by this model. The nitrogen content in the pruning residues decreased quickly in the first week but fluctuated thereafter. The initial C/N ratio was negatively related to the mineralization rate of prunings. |
| Key Words: contour hedgerow system, mineralization, N, prunings |
| Citation: Sun, H., Tang, Y. and Zhao, Q. G. 2002. Nitrogen mineralization of prunings of six N2-fixing hedgerow species in a dry valley of the Jinsha River. Pedosphere. 12(1): 15-31. |
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