Pedosphere 16(1): 125--130, 2006
ISSN 1002-0160/CN 32-1315/P
©2006 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| N mineralization as affected by long-term N fertilization and its relationship with crop N uptake |
YAN De-Zhi1,2 , WANG De-Jian1, SUN Rui-Juan1 and LIN Jing-Hui1 |
1 Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China). E-mail: dzyan@issas.ac.cn;
2 Graduate School of the Chinese Academy of Sciences, Beijing 100039 (China) |
| ABSTRACT |
| A field experiment established in 1997 was conducted to study the effect of long-term N fertilizer application on N mineralization in a paddy soil determined using a laboratory anaerobic incubation followed with a field incubation and to measure the relationship between in situ N mineralization and crop N uptake. To estimate N mineralization in the laboratory, soil samples were collected from plots with N application at different rates for six years and were incubated. Soils treated with fertilizer N mineralized more N than unfertilized soils and mineralization increased with N application rates. Also, the fraction of total N mineralized increased with increasing N fertilizer application. These findings meant that a substantial portion of previously applied N could be recovered slowly over time in subsequent crops. The field incubation of the plot receiving no fertilizer N showed that the NH4+-N concentration varied greatly during the rice-growing season and seasonal changes of N mineralization were due more to accumulation of NH4+-N than NO3--N. Rice N uptake increased up to a maximum of 82 kg N ha-1 during the season. The close agreement found between in situ N mineralization and rice N uptake suggested that the measurement of in situ N mineralization could provide useful recommendations for adequate fertilizer N application. |
| Key Words: anaerobic incubation, field incubation, N application, N mineralization, N uptake |
| Citation: Yan, D. Z., Wang, D. J., Sun, R. J. and Lin, J. H. 2006. N mineralization as affected by long-term N fertilization and its relationship with crop N uptake. Pedosphere. 16(1): 125-130. |
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