Pedosphere 22(2): 137--151, 2012
ISSN 1002-0160/CN 32-1315/P
©2012 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Influence of agricultural activity on nitrogen budget in Chinese and Japanese watersheds |
S. D. KIMURA1 , YAN Xiao-Yuan2, R. HATANO3, A. HAYAKAWA4, K. KOHYAMA5, TI Chao-Pu2, DENG Mei-Hua1, M. HOJITO6, S. ITAHASHI5, K. KURAMOCHI3, CAI Zu-Cong2 and M. SAITO7 |
1 Tokyo University of Agriculture and Technology, Tokyo (Japan)
2 Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008 (China)
3 Hokkaido University, Sapporo (Japan)
4 Akita Prefectural University, Akita (Japan)
5 National Institute for Agro-Environmental Sciences, Tsukuba (Japan)
6 Kitasato University, Towada (Japan)
7 Tohoku University, Osaki (Japan) |
| ABSTRACT |
| To analyze the effect of agricultural activity on nitrogen (N) budget at the watershed scale, a comparative study was conducted at two Japanese watersheds, the Shibetsu River watershed (SRW) and Upper-Naka River watershed (UNRW), and one Chinese watershed, the Jurong Reservoir watershed (JRW). The total area and the proportion of agricultural area (in parentheses) of the watersheds were 685 (51%), 1 299 (21%), and 46 km2 (55%) for SRW, UNRW, and JRW, respectively. The main agricultural land use in SRW was forage grassland, while paddy fields occupied the highest proportion of cropland in UNRW (11% of total area) and JRW (31% of total area). The farmland surplus N was 61, 48, and 205 kg N ha-1 year-1 for SRW, UNRW, and JRW, respectively. The total input and output for the whole watershed were 89 and 76, 83 and 61, and 353 and 176 kg N ha-1 year-1 for SRW, UNRW, and JRW, respectively. The proportion of discharged N to net anthropogenic N input was 31%, 37%, and 1.7% for SRW, UNRW, and JRW, respectively. The two watersheds in Japan showed similar proportions of discharged N to those of previous reports, while the watershed in China (JRW) showed a totally different characteristic compared to previous studies. The high N input in JRW did not increase the amount of discharged N at the outlet of the watershed due to high proportions of paddy fields and water bodies, which was an underestimated N sink at the landscape scale. |
| Key Words: anthropogenic nitrogen input, denitrification, discharged nitrogen, land use, nitrogen balance |
| Citation: Kimura, S. D., Yan, X. Y., Hatano, R., Hayakawa, A., Kohyama, K., Ti, C. P., Deng, M. H., Hojito, M., Itahashi, S., Kuramochi, K., Cai, Z. C. and Saito, M. 2012. Influence of agricultural activity on nitrogen budget in Chinese and Japanese watersheds. Pedosphere. 22(2): 137-151. |
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